Conference Program
Monday 11 February
Session on Multimessenger astronomy - EM counterparts and INTEGRAL, chaired by Erik Kuulkers
13:50 (10 min) Carlo Ferrigno ** Welcome (P)
14:00 (30 min) Marica Branchesi ** The electromagnetic hunt of gravitational-wave counterparts (I)
14:30 (20 min) Volodymyr Savchenko ** Hunting for elusive short and energetic multi-messenger transients with INTEGRAL (S)
14:50 (20 min) Peter Veres ** GRB prompt emission and synergies between gamma-ray observatories multi-messenger era (S)
15:10 (15 min) James Rodi ** GRB Real-Time Analysis with IBIS/PICsIT on board INTEGRAL (C)
15:25 (15 min) Antonios Nathanail ** Magnetized jets and explosions from the merger of a Neutron star binary (C)
15:40 (15 min) Thomas Godard ** The Past, Present & Future of INTEGRAL Operations (C)
14:00 (30 min) Marica Branchesi ** The electromagnetic hunt of gravitational-wave counterparts (I)
On August 17, 2017, the first observations of gravitational waves from the inspiral and merger of a binary neutron-star system by the Advanced LIGO and Virgo network, followed 1.7 s later by a weak short gamma-ray burst detected by the Fermi and INTEGRAL satellites marked the dawn of the multi-messenger astronomy including gravitational-waves. A world-wide observing campaign involving more than 100 instruments and covering the entire electromagnetic spectrum led to the detection and characterization of the multi-wavelength counterparts. One year of observations showed the power of this new exploration of the most energetic transients. The talk will give an overview of the astrophysical implication of GW170817 and the prospects of the upcoming runs in the hunting of gravitational-wave signals and their electromagnetic counterparts.
14:30 (20 min) Volodymyr Savchenko ** Hunting for elusive short and energetic multi-messenger transients with INTEGRAL (S)
Recent years have been marked by the accelerated development of time domain astronomy, owing to the evolution of observational techniques in wide-field rapid optical and radio surveys, as well as the development of the computing resources and methods necessary to promptly interpret overwhelmingly rich observational data. In addition, new kinds of observatories dedicated to gravitational waves and neutrinos have reached a degree of maturity that has enabled breakthrough multi-messenger observations of previously undetected fundamental physical processes in space. Short and energetic events are generally easier to separate from the background than persistent sources, and this is why the first truly multi-messenger signals were also detected as transient events. The properties or even the very nature of many of the new classes of transient sources remain obscure: they are typically associated with peculiar supernovae, mergers of compact objects, or tidal disruption events. In order to decipher the complex physical processes at play in these exceptional systems, it is vital to collect exhaustive and diverse observations of the source, and in particular, observations in different energy bands. Among the most interesting, and yet the most challenging is the observation of the hard X-ray and gamma-ray emission: it often reveals a distinct emission component that points to the most dense and energetic regions at the heart of the source. The INTEGRAL spacecraft is especially well-equipped to observe unpredictable, short-lived, and energetic hard X-ray and gamma-ray transients. It carries a collection of detectors that monitor the entire sky with over 80% duty cycle and simultaneously perform deep and sensitive observations of a large sky region spanning 30x30 degrees. Interpreting the observations collected by these instruments is challenging, especially when the analysis has to be done with real-time efficiency, a critical element needed for the community follow-up of these often quickly fading transients. I will highlight recent pioneering observations of short energetic transients made with INTEGRAL. I will begin by discussing the observations of gamma-ray bursts, in particular in association with the gravitational wave events and high-energy neutrinos. Then, I will review how INTEGRAL observations of fast hard X-ray transients helps to reveal mechanisms at the core of the some of short energetic transients likely associated with the deaths of the massive stars. Finally, I will discuss how the recent discoveries in the domain of multi-messenger transients were made possible by a global effort to achieve a new degree of automation and interoperability.
14:50 (20 min) Peter Veres ** GRB prompt emission and synergies between gamma-ray observatories multi-messenger era (S)
GRB 170817A was the first confirmed counterpart to a binary neutron star merger event and it was jointly detected by Fermi-GBM and INTEGRAL-ACS. Prompt emission observations of short gamma-ray bursts are important as they carry the bulk of the radiated energy and they are the first electromagnetic signature of the merger event. Viewing angle effects can significantly reduce the observed flux, but gravitational wave observations are constrained to nearby events making multi-messenger detections feasible. I will talk about GRBs that have similar properties as GRB 170817A in the Fermi-GBM archive (some of which are also detected by INTEGRAL-ACS). I will also discuss how we can use GRBs associated with binary neutron star mergers to constrain the prompt emission models.
15:10 (15 min) James Rodi ** GRB Real-Time Analysis with IBIS/PICsIT on board INTEGRAL (C)
In the era of multi-messenger astronomy, wide field-of-view instruments able to search for prompt electromagnetic emission from gravitational wave sources are very important. Using its spectral-timing data, the IBIS soft gamma-ray detector (PICsIT) can observe impulsive events out to ~70 degrees off-axis with a time-resolution ranging from 2 ms to several tens of ms, tunable via telecommand, in 8 broad energy channels (200 keV -2.6 MeV). Additionally, INTEGRAL's continuous telemetry data stream allows for real-time analysis on the ground to search for GRB's and other impulsive events. Here we present our initial results of triggered events detected by PICsIT with the new tools developed among the INTEGRAL GW Team to search for GW counterparts.
15:25 (15 min) Antonios Nathanail ** Magnetized jets and explosions from the merger of a Neutron star binary (C)
The connection between binary neutron star mergers with short-duration gamma-ray bursts (GRBs) was confirmed with the first coincident detection of gravitational waves together with electromag- netic radiation from GW170817. The basic paradigm for short-duration GRBs includes an ultra-relativistic jet, but the low-luminosity prompt emission together with follow-up radio and X-ray observations have hinted that this picture may be different in the case of GW170817. In particular, it has been proposed that large amounts of the magnetic energy that is amplified after the merger, can be released when the remnant collapses to a black hole, giving rise to an explosion impacting on the merger ejecta. Through numerical simulations we investigate this scenario for a range of viewing angles, injected energies and matter densities at the time of the collapse, finding that the energy injection leads robustly to a wide-angle outflow. We discuss that this type of explosions are not yet ruled out by current afterglow observations of GW170817. We further present a detailed comparison between magnetized jets and hydrodynamical jets.
15:40 (15 min) Thomas Godard ** The Past, Present & Future of INTEGRAL Operations (C)
Designed for an operational life of only 5 years, INTEGRAL celebrated its 16th birthday on 17th October, 2018, with the potential to operate until its re-entry in February, 2029. Within this context, the talk will first review past actions to ensure a safe disposal while enabling continued operations until then, which have been achieved via significant reductions in propellant consumption. It will then discuss the current activities that are ensuring maximum use of available observation time to return science data, which are being achieved by automation of both routine and contingency recovery operations. Finally, it will outline preparations underway to ensure rapid reaction to a Target of Opportunity (ToO) in support of Multi-Messenger astrophysics, which will require pre-emptive slewing to the required observation attitude.
15:55 (30 min) Coffee Break
Session on Multimessenger astronomy - Gravitational waves and kilonovae, chaired by Erik Kuulkers
16:25 (30 min) Chris Fryer ** Neutron Stars and Gravitational Wave Events (I)
16:55 (20 min) Philippe Jetzer ** LISA Science and multi-messenger astronomy (S)
17:15 (15 min) Jonas Lippuner ** r-Process nucleosynthesis and kilonova overview (C)
17:30 (3 min) Shigeyuki Karino ** Evolution of wind-fed High Mass X-ray Binaries (P)
17:33 (3 min) Celia Sanchez-fernandez ** The clock wagging its tail:INTEGRAL detection of X-ray burst-induced coronal cooling in GS 1826-24 (P)
17:36 (3 min) Mariusz Tarnopolski ** Analysis of the duration-hardness ratio plane of gamma-ray bursts using skewed distributions (P)
17:39 (3 min) Katerina Goluchova ** Power density spectra of modes of orbital motion in strongly curved space-time: obtaining the observable signal (P)
17:42 (3 min) Halim Ashkar ** Searches for TeV gamma-ray counterparts to Gravitational Wave events with H.E.S.S. (P)
17:45 (3 min) Marta Dzielak ** Comparison of spectral models for disc truncation in the hard state of GX 339-4 (P)
17:48 (3 min) Alessandro Ursi ** Detection of short GRBs and sub-threshold events with the AGILE MCAL (P)
17:51 (3 min) Janusz Ziolkowski ** The effect of the illumination on the evolution of the binary system V821 Ara/GX 339-4 (P)
The first detection of the merger of a binary neutron star system has become the poster child for multi-messenger astronomy. Gamma-ray observations, coupled with afterglow measurements (e.g. in the radio), argued strongly that the merger formed a relativistic jet. UV/Optical observations probed the wind ejecta and the infra-red measurements probed the r-process ejecta. Limits on the circum-binary medium could also test our understanding of the formation of these binaries and the formation of neutron stars themselves. In this talk, I will review our current understanding of the formation of neutron stars and neutron star binaries, focusing on the interaction between theory and observations with constraints on spins, kicks, masses, etc.
16:55 (20 min) Philippe Jetzer ** LISA Science and multi-messenger astronomy (S)
I will discuss the prospects of the space-based mission LISA to detect gravitational waves from space, which following the superb performance of the LISA Pathfinder satellite has been approved by ESA as an official mission last June 2017. I will give an overview of the main scientific goals of LISA and focus on some possible multi-messenger aspects of them, in particular for the study of the Milky Way through the gravitational radiation from Galactic binaries, some of which can also be observed by electromagnetic radiation.
17:15 (15 min) Jonas Lippuner ** r-Process nucleosynthesis and kilonova overview (C)
GW170817 marked the birth of the multi-messenger astronomy era and it confirmed the long-standing hypothesis that binary neutron star mergers are the progenitors of short gamma-ray bursts and also a site of r-process nucleosynthesis. While GW170817 has provided many novel insights into how the r-process takes place in neutron star mergers, many challenges still remain to accurately model the nucleosynthesis and subsequent kilonova emission, especially how it ties to gamma-ray observatories such as INTEGRAL. In this talk, I will provide an overview of r-process nucleosynthesis in neutron star mergers and the range of possibilities of kilonova counterparts. I will discuss the state-of-the-art understanding of kilonovae and what we learned from GW170817. I will also briefly introduce SkyNet, which is a leading nuclear reaction network that is freely available to anyone to perform nucleosynthesis calculations.
17:30 (3 min) Shigeyuki Karino ** Evolution of wind-fed High Mass X-ray Binaries (P)
17:33 (3 min) Celia Sanchez-fernandez ** The clock wagging its tail:INTEGRAL detection of X-ray burst-induced coronal cooling in GS 1826-24 (P)
17:36 (3 min) Mariusz Tarnopolski ** Analysis of the duration-hardness ratio plane of gamma-ray bursts using skewed distributions (P)
17:39 (3 min) Katerina Goluchova ** Power density spectra of modes of orbital motion in strongly curved space-time: obtaining the observable signal (P)
17:42 (3 min) Halim Ashkar ** Searches for TeV gamma-ray counterparts to Gravitational Wave events with H.E.S.S. (P)
17:45 (3 min) Marta Dzielak ** Comparison of spectral models for disc truncation in the hard state of GX 339-4 (P)
17:48 (3 min) Alessandro Ursi ** Detection of short GRBs and sub-threshold events with the AGILE MCAL (P)
17:51 (3 min) Janusz Ziolkowski ** The effect of the illumination on the evolution of the binary system V821 Ara/GX 339-4 (P)
18:00 (120 min) Welcome aperitive
Tuesday 12 February
Session on Multimessenger astronomy - GRB, chaired by Volodymyr Savchenko
09:00 (30 min) Peter Meszaros ** A theoretical framework for GRBs (I)
09:30 (25 min) Luigi Piro ** An observational overview of GRBs (S)
09:55 (20 min) J. Michael Burgess ** Gamma-ray bursts as cool synchrotron sources (C)
10:15 (20 min) Dmitrii Frederiks ** GRB observations with Konus-WIND experiment (C)
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09:30 (25 min) Luigi Piro ** An observational overview of GRBs (S)
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09:55 (20 min) J. Michael Burgess ** Gamma-ray bursts as cool synchrotron sources (C)
Gamma-ray bursts are the most energetic electromagnetic sources in the Universe. Their prompt gamma-ray radiation, lasting between a fraction of a second to several thousand seconds, corresponds to an energy release of 1E42-1E47 J. Fifty years after their discovery and several dedicated space-based instruments, the physical origin of this emission is still unknown. Synchrotron emission has been one of the early contenders, but was criticized because spectral fits of empirical models (such as a smoothly-connected broken power law or a cut-off power law) suggest too hard a slope of the low-energy power law, violating the so-called synchrotron line-of-death, reviving models of photospheric emission. Fitting proper synchrotron spectra (rather than heuristic functions) was first shown to work for individual GRBs, though without tracking electron cooling. When the latter was taken into account, several GRB spectra could be fit successfully. Here we show that idealized synchrotron emission, when properly incorporating time-dependent cooling of the electrons, is capable of fitting ~95% of all time-resolved spectra of single-peaked GRBs as measured with Fermi/GBM. The comparison with spectral fit results based on previous empirical models demonstrates that the past exclusion of synchrotron radiation as emission mechanism derived via the line-of-death were misleading. Our analysis probes the physics of these ultra-relativistic outflows and the microphysical processes which cause them to shine, and for the first time provides estimates of magnetic field strength and Lorentz factors of the emitting region directly from spectral fits. The parameter distributions that we find are grossly compatible with theoretical spectral and outflow predictions. The emission energetics remain challenging for all theoretical models. As synchrotron radiation alone can explain the observed emission, it is difficult to reconcile the time scales, efficiencies, and microphysics predicted by relativistic Fermi shock acceleration19 and the fireball model with the observations. Thus, our modeling of the Fermi/GBM observations provides evidence that GRBs are produced by moderately magnetized jets in which relativistic mini-jets emit optically-thin synchrotron radiation at large emission radii.
10:15 (20 min) Dmitrii Frederiks ** GRB observations with Konus-WIND experiment (C)
We review gamma-ray burst (GRB) observations with the Konus-Wind (KW) experiment, which provides a continuous all-sky coverage in the 20 keV-15 MeV band during the period from 1994 to present. The recent results include a systematic study of GRBs with known redshifts and a search for ultra-long GRBs in the KW archival data. We also discuss the KW capabilities for multi-messenger astronomy.
10:35 (25 min) Coffee Break
Session on Multimessenger astronomy - neutrinos, FRB, and cosmic rays, chaired by Volodymyr Savchenko
11:00 (30 min) Sara Buson ** Linking electromagnetic observations to neutrino astrophysics (I)
11:30 (15 min) Christian Gouiffes ** The 2017 INTEGRAL campaign of the Fast Radio Burst FRB121102: results and prospects (C)
11:45 (15 min) Silke Britzen ** Neutrinos from TXS 0506+056 (C)
12:00 (15 min) Andrea Tramacere ** Stochastic acceleration in blazars: theory and phenomenology with a focus on the X-ray/hard X-ray emission (C)
12:15 (15 min) Shu Zhang ** Burst probe to XRB accretion and Insight-HXMT observation (C)
The long-time efforts invested in the neutrino astronomy field have recently paid off by the discovery of a diffuse neutrino flux of astrophysical origin by the IceCube detector. The incontrovertible evidence of the existence of cosmic sources producing neutrinos has brought up new questions in astroparticle physics, and opened the quest for the identification of those emitters. While neutrino astronomy has turned into a helpful means of investigation, a lot can be learnt by using it in synergy with other mature probes. In particular, the combination of neutrino/electromagnetic information is motivated by the fact that both radiations may be pictured in the same astrophysical particle-cascades scenario, cascades that are ultimately originated by cosmic rays. Based on these assumptions, limits can be placed on the known astrophysical source classes contribution to the diffuse neutrino flux. Furthermore, a promising ground for discovery is the search for transient and variable neutrino/electromagnetic sources, in which case the atmospheric neutrino and muon backgrounds can be reduced by taking time- and space-coincidence. Recent encouraging steps in this field will be presented.
11:30 (15 min) Christian Gouiffes ** The 2017 INTEGRAL campaign of the Fast Radio Burst FRB121102: results and prospects (C)
Fast radio bursts (FRBs) are bright and very short flashes of radio waves whose origin is still matter of debate. Among the few dozen FRBs discovered today, only one, FRB121102, shows a remarkable repeating activity. The localisation of the source inside a star forming region of the host galaxy and the discovery of a large and variable rotation measure argue in favour of compact object, neutron star or magnetar. In this case, emission at the high energy band might be expected as already observed during the strong episode of flaring activities of the soft gamma ray repeaters. In that context, INTEGRAL pointed in late September 2017 towards FRB121102 for two orbits in coordination with several major radio facilities (Effelsberg, Nancay, Arecibo, GBT, FAST), optical telescopes (OHP) and VHE networks. During this talk, we will describe this observing campaign and first results. We will then discuss the strategy adopted for the 2019 campaign and address in a more general view questions and problems related to the follow-up of the fast radio bursts. This project is a collaboration between CEA/DAp, MPifR Bonn, Observatoire de Paris, NUI Galway, IAP, ISDC Geneva.
11:45 (15 min) Silke Britzen ** Neutrinos from TXS 0506+056 (C)
We used archival VLB data to perform a detailed analysis of the time evolution of the jet of TXS 0506+056. In this talk we will discuss the specifics of the jet kinematics and in particular its possible relation to neutrino emission. A paper describing the results will be submitted soon.
12:00 (15 min) Andrea Tramacere ** Stochastic acceleration in blazars: theory and phenomenology with a focus on the X-ray/hard X-ray emission (C)
I will review some of the main phenomenological signatures of the stochastic acceleration acting in the relativistic jets of blazars. I will link predictions from Monte Carlo simulations and from the numerical solution of the diffusion equation in momentum space, to the spectral features observed in the multi-wavelength SED of blazars. In particular, I will focus on the spectral evolution and spectral curvature in the X-ray/hard X-ray data and in the TeV data, and the implications on the acceleration mechanisms. Finally, I will discuss the formation of pile-up during strong flares.
12:15 (15 min) Shu Zhang ** Burst probe to XRB accretion and Insight-HXMT observation (C)
Although corona has been being well used in modelling accretion of XRBs, especially on aspects of the spectral state transitions and correlation with launching of a jet, so far its nature is still less known, especially on aspect of the formation mechanism. To probe this puzzle observationally, one has firstly to have a proper probe like the intense short soft X-ray shower, since the corona is in definition less emissive and can only be lighted up with the incident soft X-rays. This probe, however, falls short in BH XRBs, but fits well the thermal nuclear flashes occurring on the NS surface. We therefore took the type-I burst to probe the accompanied disk/corona evolution and obtained an atoll sample which shows that corona can be cooled off by the burst shower. Further studies suggest that, a variety of issues apart from corona can be addressed as well by taking this probe. The current shortage in observations at hard X-rays is the relatively poor statistics of the data, which can be diminished by the HXMT mission.
12:35 (85 min) Lunch Break
Session on Multimessenger astronomy -- neutron stars, chaired by Sandro Mereghetti
14:00 (30 min) Aleksi Vuorinen ** Constraining the equation of state of neutron star matter with observations (I)
14:30 (20 min) Matteo Guainazzi ** Multi-Messenger astrophysics with Athena (S)
14:50 (15 min) Joesph Gelfand ** MeV emission from Pulsar Wind Nebulae (C)
15:05 (15 min) Alexei Ivlev ** Gamma-Ray Emission from Molecular Clouds Generated by Penetrating Cosmic Rays (C)
15:20 (15 min) Rosario Iaria ** Spectral Analysis of the eclipsing source MXB 1659-298 (C)
15:35 (3 min) Alexandros Filothodoros ** A long term hard X-ray analysis of GRS 1758-258 using INTEGRAL data. (P)
15:38 (3 min) Jessymol K Thomas ** "MAXI J 1820+070: A new black hole low-mass X-ray binary candidate.""" (P)
15:41 (3 min) Alessandra Costantino ** Constructing an IBIS/ISGRI slew survey (P)
15:44 (3 min) Martin Urbanec ** Constraining neutron star equation of state from X-ray observations (P)
15:47 (3 min) Gabriela Urbancova ** Properties of the Hartle-Thorne epicyclic oscillations (P)
I will describe attempts to constrain the collective properties of dense nuclear and quark matter using a combination of microscopic calculations and neutron star observations. In particular, I will demonstrate that the tidal deformability limits provided by LIGO already allow for a significant reduction of the uncertainties in the equation of state of neutron star matter. After this, I will further discuss, how current and future radius measurements are expected to contribute to this program.
14:30 (20 min) Matteo Guainazzi ** Multi-Messenger astrophysics with Athena (S)
In this talk I will present the scientific objectives and design status of Athena - the Advanced Telescope for High-ENergy Astrophysics. Athena was selected in June 2014 as the second L-class mission in ESA's Cosmic Vision 2015-25 plan, with a launch foreseen in early 2030s. It is an X-ray observatory designed to address the two questions of Cosmic Vision science theme 'The Hot and Energetic Universe': a) How does ordinary matter assemble into the large-scale structures we see today? and; b) How do black holes grow and shape the Universe? It will achieve these goals by studying a wide range of astrophysical phenomena: the formation and evolution of groups and clusters of galaxies; the chemical evolution of hot baryons; feedback effects of active galactic nuclei; missing baryons thought to populate the intergalactic medium; the formation and early growth of black holes; and the accretion by super-massive black holes through cosmic time, among others. I will particularly discuss the role the Athena will play in the new era of multi-messenger astrophysics, and the natural synergies with ground-based and space-borne Gravitational Wave facilities to study merging super-massive black holes, their environment and afterglows, as well as the X-ray afterglows of NS-NS merging events. These goals will be achieved through an unprecedented combination of an X-ray telescope with a focal length of 12 m and an effective area of >=1.4 square meters at 1 keV, and two instruments: an X-ray Integral Field Unit (X-IFU) for spatially-resolved, high spectral resolution (~2.5 eV) imaging spectroscopy over an effective 5' diameter field-of-view, and a Wide Field Imager (WFI) for high count rate, moderate resolution spectroscopy over a large field of view (~40'x40'). Athena is currently in the study phase ("Phase A"") aiming at the scientifically optimal design. Upon completion, Athena will be proposed for 'adoption' on 2021, thus leading to the start of the construction phase."
14:50 (15 min) Joesph Gelfand ** MeV emission from Pulsar Wind Nebulae (C)
The detection of numerous PWNe at multi-TeV energies strongly suggest these sources produce some of the highest energy electrons and positrons in the Galaxy. However, the underlying acceleration mechanism is poorly understood. Currently, the best way of measuring the spectrum of particles accelerated inside a PWN is by fitting its observed broadband spectral energy distribution (SED) with a model for its dynamical and radiative evolution. Measuring the MeV properties of PWNe is particularly important since it is this band where the dominant emission mechanism transitions from synchrotron to inverse Compton radiation. I will present the predicted MeV properties by current modelling of known PWNe, what can be learned by measuring the MeV properties of these sources, and how this information can be used to better understand the origin of the highest energy leptons in the Milky Way.
15:05 (15 min) Alexei Ivlev ** Gamma-Ray Emission from Molecular Clouds Generated by Penetrating Cosmic Rays (C)
Co-authors: V. A. Dogiel, D. O. Chernyshov, D. Malyshev, A. W. Strong, and K. S. Cheng. We analyze the processes governing cosmic-ray (CR) penetration into molecular clouds and the resulting generation of gamma-ray emission. The density of CRs inside a cloud is depleted at lower energies due to the self-excited MHD turbulence. The depletion depends on the effective gas column density of the cloud. For the central molecular zone, the expected range of CR energy depletion is $E \lesssim 10$~GeV, leading to the depletion of gamma-ray flux below $E_\gamma \approx 2$~GeV. This effect can be important for the interpretation of the GeV gamma-ray excess in the Galactic Center, which has been revealed from the standard model of CR propagation (assuming the CR spectrum inside a cloud to be equal to the interstellar spectrum). Furthermore, recent observations of some local molecular clouds suggest the depletion of the gamma-ray emission, indicating possible self-modulation of the penetrating low-energy CRs.
15:20 (15 min) Rosario Iaria ** Spectral Analysis of the eclipsing source MXB 1659-298 (C)
The X-ray transient eclipsing source MXB 1659-298 went in outburst in 1999 and 2015, respectively. During these two outbursts the source was observed by XMM-Newton, NuSTAR and Swift/XRT. Using these observations we studied the broadband spectrum of the source to constrain the continuum components and to verify the presence of a reflection component as recently observed in the X-ray eclipsing transient source AX J1745.6-2901. We combined the available spectra studying the soft and hard state of the source in the 0.4-35 keV and 0.45-55 keV energy range, respectively. We find that the soft state can be modelled with a thermal component associated with the inner accretion disk plus a Comptonized component. A broad emission line at 6.6 keV and narrow absorption lines associated with highly ionized ions of oxygen, neon and iron are observed. We obtain a best-fit model using a smeared reflection component that fits a reflection emission from the innermost region of the system and adding a component that takes into account the ionized absorber where the narrow absorption lines forms. The equivalent hydrogen column density associated with the absorber is close to 6 10^23 cm-2. On the other hand, the direct continuum emission in the hard state can be described by a comptonized component with a temperature larger than 150 keV. Also in this state a reflection component and a ionized absorber are observed. The equivalent hydrogen column density associated with the absorber is close to 1.3 10^23 cm-2.
15:35 (3 min) Alexandros Filothodoros ** A long term hard X-ray analysis of GRS 1758-258 using INTEGRAL data. (P)
15:38 (3 min) Jessymol K Thomas ** "MAXI J 1820+070: A new black hole low-mass X-ray binary candidate.""" (P)
15:41 (3 min) Alessandra Costantino ** Constructing an IBIS/ISGRI slew survey (P)
15:44 (3 min) Martin Urbanec ** Constraining neutron star equation of state from X-ray observations (P)
15:47 (3 min) Gabriela Urbancova ** Properties of the Hartle-Thorne epicyclic oscillations (P)
15:50 (25 min) Coffee Break
Session on Multimessenger astronomy - Future perspectives, chaired by Sandro Mereghetti
16:15 (30 min) Eleonora Troja ** Search of neutron star mergers in the GRB population (I)
16:45 (20 min) Jan Uwe Ness ** Towards a better coordination of Multimessenger observations: VO and future developments (S)
17:05 (15 min) Lorenzo Amati ** The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) (S)
17:20 (15 min) Ehud Behar ** ISS-TAO (C)
17:35 (15 min) Maurizio Falanga ** Magnetic Cataclysmic Variables discovered in hard X-rays (C)
The recent discovery of a faint gamma-ray burst (GRB) coincident with the gravitational wave (GW) event GW 170817 revealed the existence of a population of low-luminosity short duration gamma-ray transients produced by neutron star mergers in the nearby Universe. These events could be routinely detected by existing gamma-ray monitors, yet previous observations failed to identify them without the aid of GW triggers. I will revisit the properties of short GRBs observed by Swift and show that a few bursts like GRB170817A could have been already detected but remained unidentified. I'll discuss the case of the peculiar GRB150101B, a likely analogue of GRB170817A located at a cosmological distance. These results suggest that the properties of GRB170817A could be common among future GW counterparts.
16:45 (20 min) Jan Uwe Ness ** Towards a better coordination of Multimessenger observations: VO and future developments (S)
The demand for multi-observatory coordinated observations has continuously increased over the last decade, and the traditional way of achieving overlap between observations will become increasingly complex in the near future. We propose international standards, certified by VO, for observatories to provide their visibility and planning information in order to make better use of automated processes. Public automated access to visibility and past/present/future observations will allow a number of additional activities. We will describe the proposed VO standards and give example of use cases.
17:05 (15 min) Lorenzo Amati ** The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) (S)
The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) is a space mission concept, developed by a large international collaboration and selected by ESA for a phase 0/A study within the Cosmic Vision - M5 selection process. THESEUS aims at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics, also in strong sinergy with the large observing facilities of the future. These goals will be achieved through a unique combination of instruments allowing GRBs and X-ray transients detection over a broad FOV (more than 1sr) with 0.5-1 arcmin localization, an energy band extending from several MeVs down to 0.3 keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7 m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will address main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift 10-12, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, THESEUS will provide a fundamental contribution to time-domain and multi-messenger astrophysics by detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which will be routinely detected in the late '20s / early '30s by next generation facilities like aLIGO/aVirgo, eLISA, KAGRA, and Einstein Telescope and, more in general, of several classes of transient sources, providing an ideal sinergy also with the large multi-wavelength observatories of the near future like LSST, ELT, TMT, SKA, CTA, ATHENA).
17:20 (15 min) Ehud Behar ** ISS-TAO (C)
The Transient Astrophysics Observer on Board the International Space Station (ISS/TAO) is a NASA mission selected for a concept study, with contributions from the Israel Space Agency. It will employ a wide field X-ray telescope in conjunction with a Gamma-ray Transient Monitor (GTM). Its primary goal is to observe electromagnetic counterparts of gravitational wave (GW) events emanating, e.g., from neutron-star binary mergers, as soon as possible after the merger. The wide field imager will employ advanced Multi Channel (Lobster) Optics on a fast slewing platform and observe several hundred square degrees at a time, thus tracking down the GW source. The GTM will detect gamma-ray bursts (GRBs) in the half-sky above the ISS and provide time coincidence with the GW event. The talk will present the ISS/TAO concept, main capabilities, and current status, as well as its unique contribution to time domain astrophysics at high energies.
17:35 (15 min) Maurizio Falanga ** Magnetic Cataclysmic Variables discovered in hard X-rays (C)
Among hard X-ray galactic sources detected by the INTEGRAL and Swift surveys, those discovered as accreting white dwarfs have surprisingly boosted in number, representing 20% of the galactic sample. The majority are identified as magnetic Cataclysmic Variabiles (mCVs) of the Intermediate Polar type suggesting this subclass as an important constituent of galactic population of X-ray sources. We will discuss the X-ray emission properties as observed with our ongoing XMM-Newton programme of newly discovered sources that enlarged almost by a factor of two, identifying commonalities and outliers.
19:00 (180 min) Social Dinner
Wednesday 13 February
Session on AHEAD - Context, chaired by Lorenzo Natalucci
09:00 (15 min) Peter Von Ballmoss Lorenzo Natalucci ** Looking AHEAD in Gamma-Ray Astronomy (S)
09:15 (30 min) Andreas Zoglauer ** Next Generation Compton Telescope (I)
09:45 (15 min) Giulia Mantovani ** NEW SCIENCE OPPORTUNITIES USING STRATOSPHERIC BALLOON (S)
10:00 (15 min) Vincent Tatischeff ** From e-ASTROGAM to an All-Sky Gamma-ray Imager (S)
10:15 (15 min) Lorraine Hanlon ** Nanosatellites for gamma-ray astronomy (S)
09:15 (30 min) Andreas Zoglauer ** Next Generation Compton Telescope (I)
COSI, the Compton Spectrometer and Imager, is a balloon-borne gamma-ray telescope (0.2-5 MeV) utilizing high-purity Germanium double-sided strip detectors. In spring 2016, COSI had a very successful 46-day balloon flight from Wanaka, New Zealand, utilizing NASA's new super-pressure balloon platform, taking COSI 1.5 times around the world. During the flight, COSI observed gamma-ray bursts, compact objects, the Galactic 511-keV annihilation emission, Galactic nucleosynthesis, and relativistic electron precipitation events. An upgraded version of COSI, called COSI-X, is currently in a competitive Phase A review as a mission of opportunity under NASA's Explorer program. COSI-X will feature more detectors with higher position resolution, an updated read-out system, and an improved anti-coincidence system, which will all together lead to significantly improved angular resolution, more resolved Compton events, higher effective area, better background rejection, and higher instrument sensitivity. The first balloon flight is planned for 2022. In the presentation, we will show the latest analysis results from COSI, especially the latest 511-keV analysis, provide a COSI-X mission overview, and present the latest soft- and hardware development towards COSI-X. These include data analysis pipeline improvements using machine-learning techniques (random forests and (deep) neural networks) for improved event reconstruction and background rejection as well as hardware developments such as the testing of our new read-out ASIC.
09:45 (15 min) Giulia Mantovani ** NEW SCIENCE OPPORTUNITIES USING STRATOSPHERIC BALLOON (S)
HEMERA is a new research infrastructure funded by the Horizon 2020 framework Programme of the European Union. It will make existing balloon facilities of Centre National d'Etudes Spatiales (CNES) and Swedish Space Corporation (SSC) available to all scientific teams in the European Union and associated states. This talk will give an overview of the project and the available opportunities for cost free stratospheric balloon flights that HEMERA can offer you.
10:00 (15 min) Vincent Tatischeff ** From e-ASTROGAM to an All-Sky Gamma-ray Imager (S)
In the era of multi-messenger astronomy, recently inaugurated by the discovery of simultaneous gravitational wave / gamma-ray and neutrino / gamma-ray signals, it is of paramount importance to have in space a gamma-ray monitor capable of detecting energetic transients in the energy range from 0.1 MeV to a few hundred MeV, with good imaging capabilities. The All-Sky-ASTROGAM mission proposal aims to place into an L2 orbit a gamma-ray instrument dedicated to fast detection, localization, and gamma-ray spectroscopy of flaring and merging activity of compact objects in the Universe, with unprecedented polarimetric capability in the MeV range. The instrument is based on the ASTROGAM concept, which combines three detection systems of space-proven technology: a silicon tracker in which the cosmic gamma-rays undergo a Compton scattering or a pair conversion, a scintillation calorimeter to absorb and measure the energy of the secondary particles, and an anticoincidence system to veto the prompt reaction background induced by charged particles. The gamma-ray imager will be attached to a deployable boom, which will be deployed when the spacecraft reaches its operational orbit, to decrease the instrument background induced by cosmic-ray interactions with the platform materials and make possible the continuous observation of every single gamma-ray source in the sky during the mission lifetime.
10:15 (15 min) Lorraine Hanlon ** Nanosatellites for gamma-ray astronomy (S)
Gamma-ray space missions have had extensive success in discovering and characterising the transient high-energy universe, including Gamma-Ray Bursts (GRBs). Their connection to catastrophic events involving stellar-mass objects means that GRBs are also excellent electromagnetic counterpart candidates to gravitational wave sources. The discovery of a short-lived gamma-ray transient by Fermi/GBM and INTEGRAL/SPI-ACS, associated with the gravitational wave source GW170817 discovered by Advanced LIGO, has provided direct evidence for the binary neutron star merger origin of a subset of GRBs. The current fleet of high energy astrophysics missions includes INTEGRAL, Swift, Fermi, and other missions that make up the Inter-Planetary Network. In many cases these missions are all approaching, or have already exceeded, their nominal lifetimes. There may therefore be a gap in the availability of future high-energy, wide-field facilities, that coincides with the timeline for major upgrades and achievement of design sensitivity for ground-based gravitational wave (GW) detectors from the early 2020's and the future LISA mission (c. 2034). One approach to ensuring all-sky coverage for the detection of GRBs is to deploy small instruments on one or more nanosatellite platforms. While having limitations of size and detector volume, there are significant advantages such as rapid implementation timescales, relatively modest costs, in-orbit technology demonstration and wide accessibility. Several such nanosatellite gamma-ray mission concepts are now in development and will be discussed in this talk.
10:30 (30 min) Coffee Break
Session on AHEAD Telescopes, Polarization, chaired by Lorenzo Natalucci
11:00 (15 min) Rui Curado Da Silva ** Polarimetry in Gamma-ray Astronomy (S)
11:15 (15 min) Nicolas Produit ** POLAR and POLAR-2 (S)
11:30 (15 min) Hsiang Kuang Chang ** Concept study of a small Compton polarimeter to fly on a cubesat (S)
11:45 (15 min) Denis Bernard ** Characterizing the performance of the MeV gamma-ray telescopes and polarimeters of the future. (C)
12:00 (15 min) Alexander Moiseev ** Investigation of the Galactic Center with GalacticCenterExplorer (GalCenEx) (C)
12:15 (15 min) Richard Miller ** Ex Luna Scientia - The Lunar Occultation Explorer (LOX) (S)
Polarimetry in the high-energy astrophysics may open a new scientific window, since so far only a few measurements were performed by instruments that were not designed for polarimetry and no dedicated polarimeter is presently operating in space. By measuring the polarization direction and the polarization degree of a celestial source, two additional observational parameters are provided the analysis of its emissions. These additional parameters should allow better discrimination between different emission models characterizing the same object. Celestial sources polarimetric analysis can provide information about the geometry, the magnetic field, the composition and the emission mechanisms. Polarized emissions are expected in a wide variety of gamma-ray sources such as pulsars, solar flares, active galactic nuclei, galactic black-holes and gamma-ray bursts. Therefore, high-energy astrophysics polarimetry may greatly benefit from e-ASTROGAM (enhanced ASTROGAM) or from AMEGO (All-sky Medium Energy Gamma-ray Observatory) mission proposals. The potential of these missions to perform polarimetric measurements are analyzed, compared and discussed.
11:15 (15 min) Nicolas Produit ** POLAR and POLAR-2 (S)
The POLAR detector has taken data from 18 September 2016 to 1st April 2017. It has detected more then 50 GRB and published polarization measurement for 5 of them. POLAR-2 is the proposed successor of POLAR featuring one order of magnitude increase in the effective area.
11:30 (15 min) Hsiang Kuang Chang ** Concept study of a small Compton polarimeter to fly on a cubesat (S)
Application of cubesats in astronomical observations has been getting more and more mature in recent years. Here we report a concept study of a small Compton polarimeter to fly on a cubesat for observing polarization of soft gamma-rays from a black-hole X-ray binary, Cygnus X-1. Polarization states provide very useful diagnostics on the emission mechanism and the origin of those gamma rays. In our study, we conducted Monte Carlo simulations to decide the basic design of this small polarimeter. Silicon detectors and cerium bromide scintillators were employed in this study. We estimated its on-axis effective area at different energies and its data telemetry requirement when flying in a low earth orbit. Based on this study, we will proceed to have a more realistic design and look for opportunities of a cubesat space mission.
11:45 (15 min) Denis Bernard ** Characterizing the performance of the MeV gamma-ray telescopes and polarimeters of the future. (C)
A number of techniques are being developed so as to solve the monstruous sensitivity gap that extends between the energy ranges of good sensitivity of the Compton and of the pair telescopes, and to extend polarimetry to the gamma-ray world. I will show how to characterize the properties of an active target in which photons convert to an e+e- pair and the two leptons are tracked, detailing the various contributions to the angular resolution [1,2], using my full five-dimensional event generator [3,4] of the Bethe-Heitler differential cross section that will have been deployed as the G4BetheHeitler5DModel physics model of the Geant4 10.5 release by the time of the conference. None of the pre-existing physics models were found appropriate to the simulation of the high-performance detectors that are being planned, nor of polarisation, nor of triplet conversions [5]. I will show how the dilution of the polarisation asymmetry induced by several harmful effects such as multiple scattering depend on the detector parameters [3], again thanks to G4BetheHeitler5DModel, and how a judicious definition of the azimutal angle of the event provides an optimal measurement [6]. In the case of a large-volume active target, the mass of a backing calorimeter adapted to measurement of the high-energy pair leptons, in addition to that of the low-energy Compton-scattered photon, might be an issue. I will present an optimal way to implement the Moliere method of measurement of the track momentum by combination of the deflections induced by multiple scattering in the tracker[2]. In the case of a silicon-wafer-based active target of the e-ASTROGAM/AMEGO class, the method can be used up to a momentum of a couple of GeV/c. [1] Nucl. Instrum. Meth. A 701 (2013) 225 [2] Nucl. Instrum. Meth. A 867 (2017) 182 [3] Nucl. Instrum. Meth. A 729 (2013) 765 [4] Nucl. Instrum. Meth. A 899 (2018) 85 [5] Astroparticle Physics 88 (2017) 60 [6] Astroparticle Physics 88 (2017) 30
12:00 (15 min) Alexander Moiseev ** Investigation of the Galactic Center with GalacticCenterExplorer (GalCenEx) (C)
The European Space Observatory INTEGRAL has been providing excellent results on X-ray and g-ray astronomy since its launch in 2004. Among the most important results are the spectroscopy and imaging measurements of celestial g-ray sources, including mapping of 511 keV radiation from Galactic plane. However the nature of the Galactic Center region 511 keV positron annihilation line is still a mystery. Similarly the structure and nature of the Galactic Center supermassive black hole and its surroundings, as well as the structure of heavily populated sky regions such as Cygnus and Carina in g-rays remain unclear. We will present a concept of a potential new-generation g-ray telescope with the major objectives a) solve the mystery of the Galactic Center region 511 keV positron annihilation line by mapping the Galactic Center region with high energy (<1% FWHM) and angular (< 10 arcmin) resolution and with line sensitivity <10-5 ph cm-2 s-1; b) understand the nature of the Galactic Center supermassive black hole environment by creating a high- resolution spectral and intensity map of the surrounding region; and c) explore Galactic chemical evolution and sites of explosive element synthesis by conducting high-sensitivity measurements of nuclear lines from supernovae 1a and from other objects. The instrument is based on a novel high-energy and position resolution CdZnTe calorimeter, coded aperture mask and heavy-scintillator shield, and can be considered for a NASA Explorer mission. GalCenEx will be capable to conduct the measurements in 100 keV - 50 MeV energy range, with energy resolution 0.5-2% (FWHM) and angular resolution ~10 arcmin. 3D position sensitivity of the CdZnTe calorimeter will enable the polarization measurements in energy range 100 keV - 5 MeV.
12:15 (15 min) Richard Miller ** Ex Luna Scientia - The Lunar Occultation Explorer (LOX) (S)
Astronomical investigations from the Moon afford new opportunities to advance our understanding of the cosmos. The Lunar Occultation Explorer (LOX) will leverage the power of a new observational technique to transform our understanding of the nuclear cosmos (0.1-10 MeV) and establish the Moon as a platform for astrophysics. LOX directly challenges traditional paradigms to mitigate mission complexity, technology development lifecycles, and cost constraints, while also delivering the sensitivity and continuous all-sky monitoring capabilities that will transform nuclear gamma-ray (MeV) astrophysics. Temporal modulation is the foundation of our approach. Operating from lunar orbit, LOX will use the Moon as a natural occulting disk to generate the required modulation via repeated eclipses of astronomical sources. The resulting occultation signatures contain all the information necessary for source characterization and localization. Simplicity is a hallmark of this efficient and validated approach. LOX's lone instrument, the Big Array for Gamma-ray Energy Logging (BAGEL) is highly scalable, limited only by available mission mass and power resources. I will review ongoing development of LOX as a next-generation nuclear astrophysics mission concept including in-situ validation of the technique from lunar orbit and discuss the benefits of the lunar environment. Several high-priority science goals will be uniquely enabled by LOX to provide new insights into the lifecycle of matter and energy in our galaxy and beyond.
12:30 (90 min) Lunch Break
Session on Extragalactic astronomy, chaired by Pietro Ubertini
14:00 (30 min) Gabriele Ghisellini ** Recent development on extra-galactic astronomy: a hard X-ray view (I)
14:30 (20 min) Elisa Prandini ** MAGIC extragalactic highlights from a MeV perspective (S)
14:50 (20 min) Stephane Paltani ** Self-consistent modeling of the environment of supermassive black holes (S)
15:10 (15 min) Gabriele Bruni ** A high fraction of restarting sources in soft gamma-ray selected giant radio galaxies (C)
15:25 (15 min) Francesco Ursini ** High-energy view of hard X-ray selected radio galaxies (C)
15:40 (15 min) Gabriel Torok ** On mass of the active galactic nucleus black hole XMMUJ134736.6+173403 (C)
Extragalactic jets pointing at us, namely blazars, are the most powerful persistent sources of the universe. Their relativistically boosted emission extends from radio frequencies to TeV energies. They are also suspected to be the sources of energetic neutrinos and high energies cosmic rays. The study of their overall spectrum indicates that most of the emission of powerful blazars is in hard X-rays or in soft gamma-rays. In this band we can find the most powerful jets, visible also at high redshifts. It is found that the jet power is linked to the accretion luminosity, and exceeds it. It is suggested that heavy black holes in jetted sources form earlier than in jet-less objects.
14:30 (20 min) Elisa Prandini ** MAGIC extragalactic highlights from a MeV perspective (S)
In the past fifteen years, the way to study TeV gamma-ray emitters changed drastically. The detection-based approach aimed at populating the TeV gamma-ray sky evolved into a physics-driven one, with the ambitious objective of understanding the mechanisms responsible for the emission and their environments. The synergic collaboration between instruments operating in different electromagnetic bands and with different messengers is therefore crucial. In this talk, I will report highlights on extragalactic physics studies achieved with the MAGIC telescopes, with special emphasis on the MeV-TeV connection.
14:50 (20 min) Stephane Paltani ** Self-consistent modeling of the environment of supermassive black holes (S)
Supermassive black holes in active galactic nuclei are surrounded by matter organized in different structures like an accretion disk, a torus, etc. Radiation interacts with these structures essentially through the mechanisms of absorption, scattering and fluorescence, making X-rays in principle a fantastic probe of the geometry of these objects. The presence of several structures makes however the processes of up- and down-scattering particularly complex and geometry-dependent; such complexity cannot be captured in models. We present a general ray-tracing simulation framework, RefleX, which is able to simulate arbitrary geometries in a fully consistent way. RefleX includes most radiation processes taking place in the soft-to-hard X-ray regime. We demonstrate the capability of RefleX by determining the X-ray properties of a system consisting of an accretion disk and a torus simulated in a self-consistent way, starting from the thermal emission of the accretion disk.
15:10 (15 min) Gabriele Bruni ** A high fraction of restarting sources in soft gamma-ray selected giant radio galaxies (C)
Cross-correlating the INTEGRAL/IBIS and Swift/BAT AGN population with radio catalogs (NVSS, FIRST, SUMSS), we found that 25% of extended radio sources are Giant Radio Galaxes (GRG), i.e. the largest individual objects in the Universe. This fraction is four time more abundant than what found in previous studies. In 2014, we observed a pilot sample of these soft-gamma ray selected GRG at low radio frequencies with the GMRT, with the aim of studying the morphological and spectral properties of these objects. Thanks to these data, we discovered the second X-shaped GRG to date, and a previously unidentified radio galaxy. Another object, observed both at kpc and pc scales, showed an extreme jet re-orientation of about 90 degrees. Given these intriguing premises, we embarked on a radio observing campaign to probe the lifecycle of these soft gamma-ray selected GRG. We found that more than half of these GRG have a nucleus with typical properties of young radio sources, while the remaining ones show a restarting radio morhology from surveys or literature data. This favour the hypothesis that Mpc-scale radio galaxies can reach their extreme extent thanks to multiple activity episodes.
15:25 (15 min) Francesco Ursini ** High-energy view of hard X-ray selected radio galaxies (C)
We discuss results of a multiwavelength study of a sample of ~70 radio galaxies, selected in the soft gamma-ray band from INTEGRAL and Swift/BAT catalogues, focusing on the X-ray view. This ongoing study is aimed at characterizing for the first time the broad-band emission of a statistically significant sample of radio galaxies. The sample contains a significantly larger fraction of giant radio galaxies (linear size > 0.7 Mpc) than typically found in radio surveys. The X-ray properties of these giant objects are consistent with an accretion-related X-ray emission, likely originating from an X-ray corona coupled to a radiatively efficient accretion flow. The relationship between the X-ray emission and the radio emission from the core and from the lobes suggests that most of these sources could have experienced episodes of restarting activity. A talk focused on the radio view and the recurrent activity of the giant objects is also proposed at this meeting (Bruni et al.). Concerning the X-ray absorption properties of the whole sample, an intriguing result is the lack of heavily absorbed (Compton-thick) sources, which could hint for a discrepancy between the absorption properties of radio-loud and radio-quiet AGNs. We also find a higher detection rate of 21 cm HI absorption among X-ray absorbed sources. This might suggest that at least part of the X-ray obscuration is due to atomic hydrogen seen at radio frequencies, and that could reside at distances larger than the classical pc-scale torus. Finally, we discuss the possible production of high-energy neutrinos from the jets and the search for spatial correlations with the ANTARES neutrino events.
15:40 (15 min) Gabriel Torok ** On mass of the active galactic nucleus black hole XMMUJ134736.6+173403 (C)
A recent study of the X-ray source XMMUJ134736.6+173403 has revealed a strong quasi-periodic modulation of the X-ray flux. The observation of two quasiperiodic oscillations (QPOs) that occur on a daily timescale and exhibit a 3:1 frequency ratio strongly supports the evidence for the presence of an active galactic nucleus black hole (AGN BH). Assuming the orbital origin of QPOs we calculate the upper and lower limit on AGN BH mass M arriving at M=(10^7-10^9)Msun. Comparing that to mass estimates of other sources, XMMUJ134736.6+173403 appears to be the most massive source with commensurable QPO frequencies, and its mass represents the current observational upper limit on AGN BH mass based on QPO observations.
15:55 (25 min) Coffee Break
Session on Galactic astronomy, chaired by Roman Krivonos
16:20 (30 min) John Tomsick ** Hard X-ray observations of Galactic sources: the HMXB population and black hole spin (I)
16:50 (20 min) Victoria Grinberg ** An obsevational view on X-ray binary black holes (S)
17:10 (15 min) Ileyk El Mellah ** Enhanced accretion and wind-captured discs in high mass X-ray binaries (C)
17:25 (15 min) Floriane Cangemi ** Long term spectral study of Cygnus X-1 using INTEGRAL (C)
17:40 (15 min) Piotr Lubinski ** Characteristic geometries of accretion in Cyg X-1 found with INTEGRAL (C)
Observations with the INTEGRAL and NuSTAR satellites are both greatly advancing our knowledge of hard X-ray sources in the Galaxy. Ever since the start of the INTEGRAL mission, it has uncovered new high mass X-ray binaries (HMXBs). That is continuing today as we have been using NuSTAR, Chandra, and ground-based observations to classify INTEGRAL sources. In addition, NuSTAR is extending the HMXB search to lower flux levels through the NuSTAR serendipitous survey. I will present on these programs and what they are telling us about the Galactic population of HMXBs. This population has received much recent attention because some of the HMXBs are the progenitors of double compact object binaries, which eventually merge and produce gravitational waves. However, measurements of black hole (BH) spin in HMXBs appear to be in conflict with the BH spins measured in binary BH mergers, and this topic will also be discussed in the presentation.
16:50 (20 min) Victoria Grinberg ** An obsevational view on X-ray binary black holes (S)
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17:10 (15 min) Ileyk El Mellah ** Enhanced accretion and wind-captured discs in high mass X-ray binaries (C)
The historical gravitational wave detections of last years ushered in a new era for the study of massive binaries evolution. In high mass X-ray binaries, a transient albeit decisive phase preceding compact binaries, a compact accretor orbits a massive star and captures part of its intense stellar wind. From the stellar photosphere down to the vicinity of the compact object, the flow undergoes successive phases. Our numerical simulations offer a comprehensive picture of the accretion process along this journey. They unveil complex and highly variable geometries produced by the wind beamed towards the accretor. Overdense small scale regions in the wind produce stochastic variability of the mass accretion rate but also trigger instabilities at the outer rim of the neutron star magnetosphere or around the black hole, depending on the nature of the accretor. For wind speeds of the order of the orbital speed, accretion is significantly enhanced and provided cooling is accounted for, transient disc-like structures form, with dramatic consequences on the torques applied to the compact object. The recent observational reports on the limited extent of the accretion disc in Cygnus X-1 suggest that the disc is produced by this mechanism rather than a Roche lobe overflow of the companion star. We will also discuss the consequences for Vela X-1 and the coupling between the flow and the neutron star magnetosphere.
17:25 (15 min) Floriane Cangemi ** Long term spectral study of Cygnus X-1 using INTEGRAL (C)
Cygnus X-1 is one of the brightest black hole X-rays binary with measured hard X-rays polarisation. The study of the two canonical states and the energy dependency of the polarisation are a way to understand accretion and ejection processes. We present here a preliminary analysis of all data that have been taken with the INTEGRAL observatory since its launch in 2003 until 2018. We exploit the joint capability of the instruments JEM-X, IBIS, and SPI, to perform a detailed state-resolved analysis in the broad 5 Kev - 2 MeV. We classify the data in 3 spectral states (hard, soft and intermediate) of individual science windows in a model-independent way. We extract the 5-400 keV stacked spectra of JEM-X and ISGRI telescopes of the soft and hard states. We then extract high energy spectra (>400 keV) in the two main states using SPI. To extract the Compton mode, we use a refined alternative method of extracting the Compton double events of the IBIS telescope. We detect a hard tail in both states. We then present study of the spectral properties of the broad band spectra based on a phenomenological model description that we have been successfully using in the past. Besides, the doube-layered IBIS detector allows us to use a Compton-mode analysis and study the polarisation properties of the hard tail in both states. We present results of this extended data base and eventually compare them to those previously reported in earlier studies. F. Cangemi, T. Beuchert, J. Rodriguez, V. Grinberg, P. Laurent, C. Gouiffes, J. Wilms
17:40 (15 min) Piotr Lubinski ** Characteristic geometries of accretion in Cyg X-1 found with INTEGRAL (C)
Thanks to seasonal pointed observations of the black hole binary Cyg X-1 carried over 15 years the INTEGRAL satellite collected the largest data set in the hard X-ray band for this source, exceeding 18 Ms of exposure time. We have analysed these data, complemented by data collected with other X-ray satellites and radio flux measured by AMI Large Array. To characterize the spectral and variability properties of the system for time scale of hours, we determined parameters such as the hard and soft X-ray flux, photon index and fractional variability. A high precision of the hard X-ray photon index GammaH determined with the INTEGRAL/ISGRI detector spectra in the 22--100 keV band allowed us to find that the GammaH distribution can be decomposed into four Gaussian peaks centered at 1.70, 1.83, 2.03 and 2.46. This result, interpreted within the Comptonization scenario as a dominant process responsible for the hard X-ray emission, leads to a conclusion that the hot plasma region in Cyg X-1 takes form of four specific geometries. A distinct character of each of these states is confirmed by different X-ray and radio variability patterns. In particular, the hardest spectral state shows no flux - photon index correlation typical for three other states, what can be interpreted as a lack of interaction between the plasma and accretion disk. An intrinsic GammaH distribution for this pure hard state is very narrow, indicating a well defined, stable limiting geometry, presumably a compact plasma region close to the black hole horizon. Our variability results in the hard X-ray band show an opposite behavior to the well-studied soft X-ray band, namely the fractional variability decreases with increasing spectral hardness, except for the hardest state showing an intermediate variability.
Thursday 14 February
Session on Galactic astronomy, chaired by Alexander Lutovinov
09:00 (20 min) Alice Borghese ** Magnetars: neutron stars at the extreme (I)
09:20 (20 min) Alessandro Papitto ** Accretion and rotation-powered pulsars: two distinct classes? (S)
09:40 (15 min) Andrea Sanna ** Observational updates on accreting millisecond X-ray pulsars (C)
09:55 (15 min) Simona Michela Mazzola ** Study of cyclical behaviour in spectral states transition of NS-LMXB systems (C)
10:10 (15 min) Khaled Alizai ** A catalog of long duration thermonuclear bursts observed with INTEGRAL (C)
10:25 (15 min) Sergey Grebenev ** New findings from the broad-band spectra of X-ray novae observed with INTEGRAL (C)
Magnetars are the strongest magnets we know of. Their X-ray emission is powered by the instabilities and decay of their huge magnetic field (~10^14 -10^15 G at the surface). The hallmark of these isolated neutron stars is the unpredictable and variable bursting activity observed in the X-/gamma ray regime and on different time scales (from milliseconds up to tens of seconds). These flaring episodes are often accompanied by enhancements of the persistent X-ray flux, which usually relaxes back to the quiescent level over months to years, the so-called outbursts. In this talk, I will review the observational properties of magnetars, showing a systematic analysis of outbursts and new results in the field. I will then finish with some considerations on magnetar-like activity from other classes of neutron stars and the possible evolutionary links between different neutron star families.
09:20 (20 min) Alessandro Papitto ** Accretion and rotation-powered pulsars: two distinct classes? (S)
A long-standing paradigm assumes that a pulsar in a binary system is not observed as a radio/gamma-ray pulsar powered by its rotation as long as matter flows towards the neutron star in an accretion disk. Indeed, millisecond pulsars are assumed to turn on as radio/gamma-ray sources only after the end of the Gyr-long, X-ray bright phase of accretion of matter from a low mass companion star that spun them up. On the other hand, transitional millisecond pulsars swing between an accretion-powered X-ray pulsar regime and a rotationally-powered radio pulsar state in a few weeks or even less and demonstrate that a pulsar may switch between different regimes on a time scale much shorter than expected. I will review the incredibly rich phenomenology of transitional pulsars, which reflects all the possible outcomes of the interaction between the pulsar wind of particles and radiation and matter in an accretion disk. In this context, the recent discovery of optical pulsations from a transitional ms pulsar suggested that a rotation-powered magnetospheric process can be active even when the pulsar is surrounded by an accretion disk. This suggests that the dichotomy between accretion and rotation-powered pulsars might be even less pronounced than previously thought.
09:40 (15 min) Andrea Sanna ** Observational updates on accreting millisecond X-ray pulsars (C)
After almost two decades from the discovery of the first accreting millisecond X-ray pulsar (AMXP) SAX J1808.4-3658, the sample of accreting rapidly-rotating neutron stars harboured in low mass X-ray binary systems has increased in number up to 22. The extremely short spin periods shown by the accreting millisecond X-ray pulsars are the result of long-lasting mass transfer from low mass companion stars through an accretion disc onto a slow-rotating NS as predicted by the so-called "recycling scenario"". At the end of the mass transfer phase, a millisecond pulsar shining from the radio to the gamma-ray band, and powered by the rotation of its magnetic field, is expected to turn on. The close link shared by radio millisecond pulsars and AMXPs has been observationally confirmed by the transitional binary systems IGR J18245 2452 as well as by other transitional millisecond pulsars. Here I will discuss the temporal and spectral properties of the recently discovered AXMPs IGR J17379-3747 and IGR J17591-2342. Moreover, I will present the latest updates on the long-term orbital evolution of the intermittent AMXP SAX J1748.9-2021 obtained combining the updated set of ephemeris from its 2017 outburst with those of the previous outbursts. The orbital period derivative will be then discussed in terms of the possible evolutionary scenarios of the binary system."
09:55 (15 min) Simona Michela Mazzola ** Study of cyclical behaviour in spectral states transition of NS-LMXB systems (C)
Authors: S.M. Mazzola (Dipartimento di Fisica e Chimica, UNIPA), E. Bozzo (Department of Astronomy, UNIGE), R. Iaria (Dipartimento di Fisica e Chimica, UNIPA), C. Ferrigno (Department of Astronomy, UNIGE), T. Di Salvo (Dipartimento di Fisica e Chimica, UNIPA), A.F. Gambino (Dipartimento di Fisica e Chimica, UNIPA) Several low mass X-ray binary systems hosting a neutron star (NS-LMXBs) show, generally, two spectral states: the so-called soft state (SS) and hard state (HS). The spectral state of a NS-LMXB source moves from hard to soft (and vice-versa) over the time and the detection and recognition of transitional states is actually a challenging task. Recently, it was observed that some of these sources shows a hysteresis-like pattern in their hardness-intensity diagram (HID) and rms variability-intensity diagram (RID): the systems evolve from HS to SS and come back to the former state following a specific evolution track (Munoz-Darias et al. 2014). Since these sources seem to follow similar track, we can expect to recover the same patterns studying their spectral variability on long temporal baseline. Then, we used the INTEGRAL data collected in the last fifteen years to reproduce the HID for a sample of persistent NS-LMXBs. We extracted the broadband spectrum from several regions of the HID for each source in order to understand cyclical spectral variations (if present) and highlight the different spectral states which each source goes through. We investigated the spectral behaviour and we determined the average properties in HS, SS and in the transitional states (identified as hard-high and soft-low states) for each one. The obtained results encourage us to extend this study to all the persistent NS-LMXBs (about 30 sources) detected by INTEGRAL.
10:10 (15 min) Khaled Alizai ** A catalog of long duration thermonuclear bursts observed with INTEGRAL (C)
Type-I X-ray bursts are caused by unstable thermonuclear burning of accreted matter on the surface of neutron star. A typical Type-I X-ray burst has a fast rise followed by a decay time of a couple of tens of seconds, and is thought to be He or He/H ignited bursts in a ~1m thick layer. This unstable burning produces carbon (C) and heavier elements, that sink deeper into the 'ocean' of the neutron star. A very rare type of X-ray bursts with duration of several hours are called superbursts. So far ~27 of these superbursts have been detected, and the current explanation for these events is an unstable burning of carbon in a deep layer (~100m). About ~70 bursts of a duration of few tens of minutes have been detected, whose duration and energy release are intermediate between the typical X-ray bursts, and the very rare superbursts. They are most likely caused by an unusually thick He layer. INTEGRAL has, to date, observed 16 intermediate bursts and 1 superburst. In this talk, a catalog of these long bursts (16+1), which includes a new method for time-resolved spectral analysis of the bursts, will be presented. Besides the spectral analysis and fitting of the light curves, an update on the archival search will be given. Lastly, some of the challenges of observing these events with INTEGRAL will be mentioned.
10:25 (15 min) Sergey Grebenev ** New findings from the broad-band spectra of X-ray novae observed with INTEGRAL (C)
We present observations of several X-ray novae in different spectral states carried out simultaneously in X-ray (INTEGRAL, SWIFT/XRT and BAT) and optical/infrared (OIR) (SWIFT/UVOT, RTT-150) bands. We show that in all the cases a bulk of the observed OIR emission was determined by extension of the power-law spectral component responsible for the hard X-rays. A contribution of the outer region of an accretion disc, even taking into account X-ray heating of its surface, is very moderate during the high state of the sources (when a soft black-body component dominates in their spectra) and is negligible during their low (hard) state. This result suggests that a notable portion of their OIR emission is formed in the same region where the hard X-rays are produced. It may be Comptonized emission from the hot central region or synchrotron emission from the disc's corona or jets.
10:40 (10 min) Mike Revnivtsev Prize Award Cerimony
10:50 (15 min) Coffee Break
Session on Galactic astronomy, chaired by Jerome Rodriguez
11:05 (20 min) Jerome Chenevez ** NICER overview and results so far (I)
11:25 (20 min) Gianluca Israel ** The Extragalactic Population of Neutron Stars: the ULX paradigm revolution (S)
11:45 (15 min) Alexander Lutovinov ** Accreted highly magnetized neutron stars: recent progress (C)
12:00 (15 min) Maica Clavel ** NuSTAR search for HMXBs among the unidentified INTEGRAL sources (C)
12:15 (15 min) Peter Kretschmar ** Vela X-1 as a laboratory for accretion in High-Mass X-ray Binaries (C)
12:30 (15 min) Andrzej Zdziarski ** Disc truncation and relativistic effects in inner accretion flows in black-hole binaries (C)
12:45 (15 min) Ilya Mereminskiy ** Timing and spectral view on accretion disk trucation radius (C)
The Neutron star Interior Composition Explorer (NICER) has been observing a number of X-ray sources since July 2017 from the International Space Station. With both high timing and good energy resolutions, the soft X-ray coverage of NICER is particularly well-suited for investigating magnetically-powered isolated neutron stars, rotation-powered millisecond pulsars, X-ray pulsars, and X-ray bursters, as well as other accreting compact objects like black holes and white dwarfs. The talk will present the NICER payload and the main results obtained from the 1 1/2 -year baseline mission for studies of neutron star energetics, dynamics, and structure, as well as expectations for the coming guest observer program.
11:25 (20 min) Gianluca Israel ** The Extragalactic Population of Neutron Stars: the ULX paradigm revolution (S)
The recent discovery of ULXs showing fast and rapidly evolving pulsations (PULXs) unambiguously associated these sources to accreting neutron stars (NSs) exceeding up to more than 500 times their LEdd. These sources challenge our understanding of accretion physics and pose a key question about the nature of the ULXs as a class. I will discuss the evidences for a high magnetic field close to the pulsar surface and the possible reason(s) for which a relatively small number of PULXs have been discovered so far. Preliminary results from a search for new PULXs in both archival XMM data and those from the UNSEeN XMM-Newton project will be also shown.
11:45 (15 min) Alexander Lutovinov ** Accreted highly magnetized neutron stars: recent progress (C)
We present a review of current results of studies of transient highly magnetized neutron stars accreting in a broad range of rates - from ultra-high rates, in which the radiation characteristics are determined by the physical properties and geometry of the accretion flows, to super-low ones, in which the radiation is associated with the cooling of a neutron star. Using data from NuSTAR, INTEGRAL, Swift, Chandra and XMM-Newton several dozen X-ray pulsars were studied in different states that allowed us to discover a propeller effect for several systems and, at the same time, to reveal an unexpected quasi-stable state for other systems associated with the accretion from cold (non-ionised) disc. We argue that a transition to one or another state determines by a combination of the rotation frequency and magnetic field strength. Additionally, a systematic investigation of X-ray pulsars in their quiescent states showed, that all systems can be roughly divided into two distinct groups: i) relatively bright objects (L~10^34 erg/s) and (hard) power-law spectra, and ii) fainter ones showing thermal spectra. The spectral and temporal characteristics of the registered emission and their evolution made it possible to obtain new estimates of the parameters of neutron stars and the properties of matter near them.
12:00 (15 min) Maica Clavel ** NuSTAR search for HMXBs among the unidentified INTEGRAL sources (C)
The NuSTAR legacy program 'Unidentified INTEGRAL sources' targeted faint hard X-ray sources revealed by INTEGRAL in the Galactic plane in order to provide conclusive identification of their nature and insights on the population of faint hard X-ray sources. The NuSTAR and Swift/XRT observations obtained in 2015-2017 led to the successful identification of five persistent INTEGRAL sources as either magnetic CVs or extragalactic sources. Combined with several other multi-wavelength identifications, these results are refining our knowledge of the surface density of HMXBs towards low fluxes.
12:15 (15 min) Peter Kretschmar ** Vela X-1 as a laboratory for accretion in High-Mass X-ray Binaries (C)
Vela X-1 is an eclipsing high mass X-ray binary (HMXB) consisting of a 283s accreting X-ray pulsar in a close orbit of 8.964 days around the B0.5Ib supergiant HD77581 at a distance of just 2.0 kpc. The system is considered a prototype of wind-accreting HMXB and it has been used as a baseline in different theoretical or modelling studies. We discuss the observational properties of the system and the use of the observational data as laboratory to test recent developments inmodelling the accretion process in High-Mass X-ray Binaries (e.g., Sander et al. 2018, El-Mellah, Keppens & Sundqvist 2018), which range from detailed descriptions of the wind acceleration to modelling of the structure of the flow of matter close to the neutron star and its variations.
12:30 (15 min) Andrzej Zdziarski ** Disc truncation and relativistic effects in inner accretion flows in black-hole binaries (C)
I will present a number of results related to the relative importance of relativistic effects in accreting flows onto black holes. In particular, I will review the current evidence for and against an accretion inner disc truncation in the hard spectral states of black-hole binaries. The spectral-fitting results of our group imply significantly truncated discs, similarly as inferred from soft X-ray lags. On the other hand, the popular lamppost geometry postulates the primary X-ray source to be located on the rotation axis of the black hole, with a number of published results giving the source location very close to the horizon. This results in most of the emitted photons crossing the horizon, which then requires a major increase of the accretion rate as inferred from the observed luminosity. Also, the implied large intrinsic lamppost luminosity results in runaway electron-positron pair production. We acknowledge funding from the European Union's Horizon 2020 Programme under the AHEAD project (grant agreement n. 654215).
12:45 (15 min) Ilya Mereminskiy ** Timing and spectral view on accretion disk trucation radius (C)
The type-C QPOs, usually found during low-hard states of X-ray novae outbursts, are commonly associated with the Lense-Thirring precession of hot accretion flow inside the disc truncation radius, with QPO frequency dependent on compact object mass. Another method to measure the truncation radius rely on a spectral analysis, particularly on the shape of broadened iron line. Using outbursts of MAXI J1535+571 and GRS 1739-278 we show, that if both of these methods are correct, then unrealistically large mass of black hole is needed.
13:00 (60 min) Lunch Break
Session on AHEAD Compton- and Pair-telescopes, chaired by Peter von Ballmoos
14:00 (30 min) Torsten Ensslin ** Information Field Theory for Gamma-Ray Astronomy (I)
14:30 (15 min) Carolyn Kierans ** The All-Sky Medium Energy Gamma-Ray Observatory (S)
14:45 (15 min) Paolo Cumani ** Background of Gamma-Ray telescopes in low-Earth orbit (S)
15:00 (15 min) Aleksandar Gostojic ** Gamma-ray background study for future Compton-telescope missions using COSI flight data (S)
15:15 (15 min) Peter Bloser ** The Advanced Scintillator Compton Telescope (ASCOT) (S)
15:30 (15 min) Aldo Morselli ** Instruments optimizations for low energy Gamma-ray detection (S)
To turn discrete data like photon counts into an image of the underlying radiation field an information theory for fields is required. Information field theory (IFT) is exactly this. In this talk, I introduce into IFT and show its astrophysical applications with a focus on event based imaging. (Thi is an invited talk)
14:30 (15 min) Carolyn Kierans ** The All-Sky Medium Energy Gamma-Ray Observatory (S)
The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a NASA Astrophysics Probe mission concept designed to explore the MeV sky. AMEGO is sensitive from ~200 keV to >10 GeV by tracking Compton and pair-production events in the same detector volume. AMEGO will enable novel capabilities in MeV astrophysics: sensitive continuum spectral studies, polarization, and nuclear line spectroscopy. As a wide-field survey gamma-ray instrument, AMEGO will be a key player in multimessanger astrophysics. The instrument will be comprised of four subsystems: a double-sided silicon tracker, a segmented CZT calorimeter, a segmented CsI calorimeter, and a plastic anticoincidence shield. In this presentation we will describe the AMEGO mission concept and expected scientific performance.
14:45 (15 min) Paolo Cumani ** Background of Gamma-Ray telescopes in low-Earth orbit (S)
The different background components in a low-Earth orbit have been modeled in the 10 keV to 100 GeV energy range. The model is based on data from previous instruments and it considers both primary and secondary particles, charged particles, neutrons and photons. The necessary corrections to consider the geomagnetic cutoff are applied to allow the calculation of the flux at different inclinations and altitudes for a mean solar activity. Activation simulations from such a background have been carried out using the model of a possible future gamma-ray mission (e-ASTROGAM). The event rates and spectra from these simulations were then compared to those from the isotopes created by the particles present in the South Atlantic Anomaly (SAA).
15:00 (15 min) Aleksandar Gostojic ** Gamma-ray background study for future Compton-telescope missions using COSI flight data (S)
The COmpton Spectrometer and Imager (COSI) is a balloon-borne Compton telescope mission aimed for gamma-ray astronomy and study novel instrument technology. In 2016 COSI was launched from New Zealand and operated for 46 days, before landing in South America. We studied the measured gamma-ray background during the flight, with the aim to create predictive models for space missions using cross-strip Germanium Detectors (GeDs). The flight covered a wide range of altitudes and latitudes, which we incorporate via position defining parameters, i.e. residual atmospheric mass and cut-off rigidity. Combining the available data in the energy range 0.1 - 2 MeV, we build a semi-empirical background model for GeDs within the atmosphere. This model is used as a basis for obtaining background spectra in LEO and L2 orbits for a COSI-type instrument.
15:15 (15 min) Peter Bloser ** The Advanced Scintillator Compton Telescope (ASCOT) (S)
There is a need in high-energy astronomy for new soft- to medium-energy gamma-ray observations, ideally covering the energy range from 0.2 - 100 MeV, to expand on the success of the COMPTEL instrument on CGRO. As this is a particularly difficult energy range to study, progress has been slow in the medium-energy band, despite the important contributions of INTEGRAL in gamma-ray lines and polarimetry. Gamma-ray astronomy communities around the world are actively studying a multitude of technological approaches to close the MeV Sensitivity Gap." I describe one such approach: building directly on the legacy of COMPTEL by using modern, fast scintillators that improve instrument response while preserving time-of-flight background rejection. Fortunately, high-performance scintillators, such as Cerium Bromide and p-terphenyl, and compact light readout devices, such as silicon photomultipliers (SiPMs), are commercially available and capable of meeting this need. The University of New Hampshire has constructed an Advanced Scintillator Compton Telescope (ASCOT) with SiPM readout, with the goal of demonstrating this technology by imaging the Crab Nebula at MeV energies during a high-altitude balloon flight. The ASCOT balloon payload was launched from Palestine, TX, on July 5, 2018, and operated successfully at a float altitude of ~122,000 feet for five hours while the Crab was high in the sky. I will present the scientific motivation for the ASCOT concept, describe the instrument and balloon payload in detail, and give a preliminary overview of the flight data and analysis to be carried out. I will also briefly introduce a new detector technology that has the potential to make the ASCOT approach to gamma-ray astronomy even more powerful."
15:30 (15 min) Aldo Morselli ** Instruments optimizations for low energy Gamma-ray detection (S)
There is an experimental gap in the study of the non-thermal universe in the photon energy range from 300 kev to 3 GeV. We have analysed the performance of a detector with unprecedented sensitivity, angular and energy resolution and combined with polarimetric capability to study of the most powerful Galactic and extragalactic sources and with a line sensitivity in the MeV energy range two orders of magnitude better than previous generation of instruments that can determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy.
15:45 (30 min) Coffee Break
Session on AHEAD - Detection of Gamma-Ray Bursts, chaired by Peter von Ballmoos
16:15 (15 min) Bertrand Cordier ** SVOM (S)
16:30 (15 min) Filippo Frontera ** ASTENA, a new mission concept for an Advanced Surveyor of Transient Events and Nuclear Astrophysics (S)
16:45 (15 min) Enrico Virgilli ** The Wide Field Monitor and Narrow Field Telescope on board the ASTENA mission (C)
17:00 (15 min) Luciano Burderi ** The HERMES project (High Energy Rapid Modular Ensemble of Satellites): probing pace-time quantum foam and hunting for gravitational wave electromagnetic counterparts. (S)
17:15 (15 min) Judith Racusin ** BurstCube: A CubeSat for Gravitational Wave Counterparts (S)
17:30 (15 min) Matthew Kerr ** Glowbug, a Gamma-Ray Telescope for Bursts and Other Transients (C)
17:45 (3 min) Debora Lancova ** Global GRRMHD simulation of thin accretion disc stabilized by magnetic field (P)
17:48 (3 min) Niels Lund ** Special features in JEM-X OSA-11 (P)
17:51 (3 min) Aymeric Sauvageon ** ISGRI: background evolution and noisy pixel handling (P)
17:54 (3 min) Philippe Laurent ** XGRE: a TGF/GRB detector on the TARANIS space mission (P)
17:57 (3 min) Lingsong Ge ** Bayesian Hierarchical Method of AGN X-ray Spectral Fitting (P)
16:30 (15 min) Filippo Frontera ** ASTENA, a new mission concept for an Advanced Surveyor of Transient Events and Nuclear Astrophysics (S)
Within the context of the European project AHEAD, the study of a new concept of high energy mission named ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics) has been started. The mission includes a set of broad band (1-20 MeV) Wide Field Monitors with imaging and spectroscopy capabilities (WFM-IS), and a large effective area broad-band (50-700 keV) Narrow Field Telescope (NFT) with focusing capabilities based on the use of an advanced Laue lens with unprecedented sensitivity. ASTENA is expected to be a real breakthrough in the gamma-ray energy band, opening a new window in high energy astrophysics. The key science goals of the mission concept and its description will be reported.
16:45 (15 min) Enrico Virgilli ** The Wide Field Monitor and Narrow Field Telescope on board the ASTENA mission (C)
The ASTENA mission, conceived within the EU funded the AHEAD framework, consists of two coaligned instruments, a broad band Wide Field Monitor/Spectrometer WFM/S and a broad band Narrow Field Telescope (NFT). In the NFT a large geometric area Laue lens (3~m diameter, 20 m focal length) allows to focus the radiation of the 50 - 700 keV energy pass-band. Differently from other proposed Laue lenses in the past, the NFT is made of optimised thickness bent crystal tiles, made with Silicon and Germanium. With these assumption we have optimised the instrument Field of View (FoV) to 3.5 arcmin with the angular resolution of 20. The Laue lens is coupled with a high efficiency (>80% above 600 keV) focal plane position sensitive detector, with 3D spatial resolution of at least 300 micron in the (X,Y) plane and fine spectroscopic response (1% @511 keV) and with polarization sensitivity. In this paper we will mainly describe the NFI geometry and its simulated performances but also an overview on the main satellite configuration and a description of all the instruments will be done. The wide field monitor and spectrometer (WFM/S), mainly dedicated to GRBs, is composed by different units and is sensitive in the range 1 keV - 20 MeV. Its total isotropic detection area will be 3.0 m^2 with a FOV of about 1.35 sr. The WFM will allow the detection and spectroscopic and polarimetric characterization of all classes of GRBs. Each WFM module is a coded mask telescope that will allow the source localization within few arcmin up to 50 - 100 keV. The detector core is based on the coupling of low-noise, solid-state Silicon Drift Detectors (SDDs) with CsI(Tl) scintillator bars. Low-energy and high-energy photons are discriminated using the on-board electronics. The instrument design and preliminary experimental characterizations are reported and discussed in this talk."
17:00 (15 min) Luciano Burderi ** The HERMES project (High Energy Rapid Modular Ensemble of Satellites): probing pace-time quantum foam and hunting for gravitational wave electromagnetic counterparts. (S)
I discuss how several of the proposed models for space-time quantization predict an energy dependent speed for photons. Although the predicted discrepancies with the general speed of light are minuscule, I discuss how it is possible to detect this intriguing signature of space-time granularity with a new concept of modular observatory for photons in the energy band 10 keV -- 30 MeV. This observatory may consist of a swarm of micro/nano- satellites on low orbits. Sub-microsecond time resolution and wide energy band allows to probe tiny energy dependent delays, expected to be the signature of the granular structure of space- time in several of the proposed theories of Quantum Gravity. Moreover this kind of experiment allows to perform temporal triangulation of high signal to noise impulsive events with positional accuracies of few arcseconds, making an observatory like that a promising hunter for the elusive electromagnetic counterparts of Gravitational Waves.
17:15 (15 min) Judith Racusin ** BurstCube: A CubeSat for Gravitational Wave Counterparts (S)
BurstCube is at the forefront of the next generation of gamma-ray burst detectors that are small, compact, low-cost, and combined with current and future similar instruments, will provide all-sky coverage for rare and unusual transients. The primary goal for BurstCube is to detect short duration gamma-ray bursts in coincidence with gravitational waves from binary neutron star mergers. All-sky coverage is especially important as the advanced gravitational wave network will reach design sensitivity in the early 2020's. I will present the current status of the development of the BurstCube mission, its scientific and technical goals, and plans for launch in 2022.
17:30 (15 min) Matthew Kerr ** Glowbug, a Gamma-Ray Telescope for Bursts and Other Transients (C)
We describe Glowbug, a gamma-ray telescope for bursts and other transients in the 30 keV to 2 MeV band. It was recently selected for funding by the NASA Astrophysics Research and Analysis program, with an expected launch in the early 2020s. Similar in concept to the Fermi Gamma Burst Monitor (GBM) and with similar sensitivity, Glowbug will join and enhance future networks of burst telescopes to increase sky coverage to short Gamma-Ray Bursts (SGRBs) from neutron star (NS) binary mergers, including possible SGRBs from NS-black hole mergers. With the recent discovery of the SGRB coincident with the gravitational wave transient GW170817, we know such events occur with reasonable frequency. Expanded sky coverage in gamma rays is essential, as more detections of gravitational waves from such mergers by ground-based interferometers will come in the next few years, and detecting an electromagnetic counterpart is a powerful probe of merger dynamics. Work on Glowbug at NRL is supported by NASA and the Chief of Naval Research.
17:45 (3 min) Debora Lancova ** Global GRRMHD simulation of thin accretion disc stabilized by magnetic field (P)
17:48 (3 min) Niels Lund ** Special features in JEM-X OSA-11 (P)
17:51 (3 min) Aymeric Sauvageon ** ISGRI: background evolution and noisy pixel handling (P)
17:54 (3 min) Philippe Laurent ** XGRE: a TGF/GRB detector on the TARANIS space mission (P)
17:57 (3 min) Lingsong Ge ** Bayesian Hierarchical Method of AGN X-ray Spectral Fitting (P)
Session on INTEGRAL data analysis (special), chaired by Guillaume Belanger
18:05 (15 min) Andrii Neronov ** Online Data Analysis system of CDCI (C)
18:20 (30 min) Guaillaume Belanger ** Special session on INTEGRAL in the astrophysics community (S)
I will present functionalities of Online Data analysis system developed at Common Data Centre Infrastructure for astronomy, astroparticle physics and cosmology at Geneva University. The system allows to perform on-the-fly standard INTEGRAL data analysis with Offline Science Analysis software for ISGRI and JEM-X instruments.
18:20 (30 min) Guaillaume Belanger ** Special session on INTEGRAL in the astrophysics community (S)
Friday 15 February
Session on Gamma-ray lines, chaired by Roland Diehl
09:00 (20 min) Thomas Siegert ** INTEGRAL contributions to gamma-ray line studies (S)
09:20 (30 min) Fiona Helen Panther ** Gamma-ray lines in modern astrophysics (I)
09:50 (15 min) Christoph Weinberger ** Ti44 emission from young galactic supernova remnants (C)
10:05 (15 min) Moritz Pleintinger ** 26Al in the ISM throughout the Galaxy: Models versus Observations (C)
10:20 (15 min) Angela Malizia ** INTEGRAL view of the extragalactic sky (C)
During its 16 years in space, the INTEGRAL mission contributed more to astrophysical soft gamma-ray line measurements than any other observatory before. With the high spectral resolution telescope SPI and the imager IBIS, a multitude of gamma-ray lines have been detected, characterised, and used as tools to study the environments of a variety of sources and regions. In this talk, I will review the milestones of INTEGRAL gamma-ray line measurements, the developments and progress of research over time, and provide an outlook what still remains to be discovered in the legacy data base of all INTEGRAL instruments. The review will include the 511 keV line from positron annihilation in the bulge and disk of the Galaxy, MeV-line emission of decaying long-lived radioactive nuclei, such as 26-Al and 60-Fe from massive stars and their core-collapse supernovae, and immediate energy providers in explosive events as traced by the decay-chains from 7-Be, 22-Na, 44-Ti, and 56-Ni. INTEGRAL has also contributed to solar physics and cosmic-ray studies by measurements of excitation lines of stable 2-H, 12-C, 16-O, as well as pulsar characteristics due to cyclotron lines. I will present the unique information about these objects, that can only be extracted by measurements of gamma-ray lines.
09:20 (30 min) Fiona Helen Panther ** Gamma-ray lines in modern astrophysics (I)
Gamma-ray astronomy provides a direct window into the most violent, dynamic processes in the universe. MeV gamma-ray astronomy in particular allows us to directly observe the process of chemical enrichment of the ISM through the decay of radioactive isotopes synthesised by stars and compact objects during their lives, in their death throes and after their deaths. Moreover, gamma ray lines such as the positron annihilation line can give us unique insights into the propagation of cosmic rays in the Galaxy, as well as hints about unusual transient phenomena which may be responsible for producing the positrons. I will give a theoretical perspective on how gamma-ray astronomy can inform our study of galactic chemical evolution, stellar populations, supernovae and cosmic ray propagation.
09:50 (15 min) Christoph Weinberger ** Ti44 emission from young galactic supernova remnants (C)
Supernovae are main contributors in enriching the universe with isotopes heavier than lithium. The explosion mechanisms are still not unterstood neither for Core Collapse nor for Supernova of Type Ia. Observing in the optical bands is limited and indirect, from overlying envelope material, whereas radioactive isotopes can be observed in hard X-ray and gamma ray energy range and reflect inner explosion physics, both from their abundance and line shapes. 44Ti emits two decay photons at 68/78 keV and one at 1157keV, all in the energy range of SPI on INTEGRAL. We report our search for young galactic supernova remnants in all 3 lines with SPI data from 16 years of observation. We also utilize the high energy resolution of SPI to put kinematic constraints on the explosion dynamics of the Cas A SN where a clear signal is seen in all three lines. We discuss the implications for SN physics, comparing to theoretical models and the issues raised from these. Specifically, results of a galactic survey in the latitude interval -18deg < b < 18deg will be given, following a descripton of SPI data analysis and background modeling. We report detailed analysis of the known young supernova remnants G1.9+0.3, Kepler SNR, Tycho SNR, Vela jr and Cassiopeia A as well as SN1987A located in the LMC.
10:05 (15 min) Moritz Pleintinger ** 26Al in the ISM throughout the Galaxy: Models versus Observations (C)
The interstellar medium in our Galaxy is of complex morphology and highly dynamic, commonly modelled via 3D MHD simulations. Observations of the ISM are difficult due to biases in each of the known tracers. Here we exploit measurements with INTEGRAL/SPI of the gamma-ray line emission at 1.8 MeV from 26Al. This diffuse radioactivity complements multi-wavelength observations as a tracer of massive star energy and mass ejections as well as their feedback, addressing ongoing nucleosynthesis. Gamma-ray emission from radioactive isotopes is independent from gas density and temperature. 26Al nuclei are ejected mainly in strong stellar winds (Wolf-Rayet phase) and supernova explosions. Because their lifetime of ~1 Myr is comparable to the crossing time of massive star ejecta inside superbubbles. Therefore, the diffuse emission is closely connected to the dynamical feedback of massive star groups onto the structure of the Galaxy's ISM. Investigating these circumstances provides a unique nexus between stellar physics and galactic evolution. A modeling concept based on the current understanding of feedback processes of massive OB associations on the superbubble scale will be given. This includes the description of recent chemodynamical simulations as well as our astrophysical bottom-up model starting from star clusters and their models, via population synthesis, to compose the predicted impact of massive star groups on the ISM in the Milky Way. It will then be discussed how we can compare such simulations with SPI measurements. This opens the possibility to validate 3D ISM modeling and the spatial distribution of the large-scale 26Al emission and to test the underlying assumptions of stellar nucleosynthesis and feedback.
10:20 (15 min) Angela Malizia ** INTEGRAL view of the extragalactic sky (C)
In its 17 years of life, INTEGRAL has provided an important contribution to the extragalactic science. Of the around 500 AGN detected by IBIS in the 20 -100 keV energy range, univocally identified, we are now able to study their spectral characteristics over a broad band energy range using INTEGRAL/ISGRI spectra in conjunction with soft 2-10 keV data available from the archives. In this talk I will present a few among the new results obtained by exploring these data in terms of AGN spectral properties and their connection with the host galaxies.
10:35 (25 min) Coffee Break
Session on Surveys, chaired by Pietro Ubertini
11:00 (30 min) Dominique Eckert ** The eROSITA all-sky survey (I)
11:30 (15 min) Roman Krivonos ** Recent results from hard X-ray surveys (S)
11:45 (15 min) Tony Bird ** INTEGRAL Surveys - the search for transients (S)
12:00 (15 min) Victoria Lepingwell ** Machine learning for source detection in IBIS/ISGRI data. (C)
12:15 (15 min) Werner Collmar ** The CGRO/COMPTEL Allsky Survey at MeV Energies (C)
12:30 (10 min) Carlo Ferrigno ** Concluding remarks (P)
eROSITA is a new wide-field X-ray instrument that will be flown on board the German/Russian SRG mission. eROSITA will perform an all-sky survey in the X-ray range (0.5-10 keV) that will be 20 times deeper than its predecessor the ROSAT all-sky survey. I will give an overview of the mission and of the main scientific goals, focusing mainly on the galaxy cluster survey and its impact on cosmology.
11:30 (15 min) Roman Krivonos ** Recent results from hard X-ray surveys (S)
The INTEGRAL observatory has been successfully operating in orbit since 2003. On the basis of the data obtained, many studies have already been done on the study of the properties of X-ray sources in our Galaxy and beyond. Using the dataset of the INTEGRAL, accumulated over 14 years, we managed to build the most ever sensitive X-ray maps of the Galactic plane, which allows us to detect either nearby low-luminosity sources or bright objects in more distant parts of the Galaxy. In this short review I will also present the results of optical identification of 11 previously unknown X-ray sources detected during the 14-year survey of the Galaxy.
11:45 (15 min) Tony Bird ** INTEGRAL Surveys - the search for transients (S)
The long duration of the INTEGRAL mission has required new methods to detect non-persistent sources within the dataset. Hard X-ray sources show a remarkable variety in their temporal variability characteristics, and both blind and tuned search techniques can be used to find them. I will discuss some of the methods developed, the challenges, and some of the highlights of sources discovered so far.
12:00 (15 min) Victoria Lepingwell ** Machine learning for source detection in IBIS/ISGRI data. (C)
While INTEGRAL has been in orbit for over 16 years the amount of data it is collecting is ever increasing. Traditional methods used to produce catalogs from the data are becoming untenable to use. Machine learning can be used to streamline the cataloging process; not only decreasing the time spent to generate these catalogs but also addressing human subjectivity. This talk will discuss how a deep learning technique (convolutional neural network) has been developed to detect sources in IBIS/ISGRI maps to help with the next catalog.
12:15 (15 min) Werner Collmar ** The CGRO/COMPTEL Allsky Survey at MeV Energies (C)
W. Collmar & A. W. Strong MPE Garching The COMPTEL experiment aboard the Compton Gamma-Ray Observatory (CGRO) surveyed the MeV sky (0.75 - 30 MeV) almost uninterruptedly for more than 9 years between April 1991 and June 2000. Thereby providing a first allsky look at the MeV band. Now, more than 18 years after the deorbit of CGRO, COMPTEL data analyses are being still pursued, using new imaging techniques as well as well as new background reduction techniques. Because no instrumental successor is yet operating, the COMPTEL data are still the forefront of our knowledge on the MeV sky. We will summarise COMPTELs observational status on the MeV sky by proving newly generated allsky maps in different energy bands and for different time periods. We will also present all-mission MeV spectra and lightcurves for the most prominent MeV sources (e.g. Crab, 3C 273, Cyg X-1), which are visible in these allsky images. We will also provide an updated list of the yet detected COMPTEL sources, and finally discuss the scientific perspectives of the still ongoing COMPTEL data analyses.
12:30 (10 min) Carlo Ferrigno ** Concluding remarks (P)
(I - invited speaker, S - solicited speaker, C - contributed talk)