For the first time, we use the Gamma-ray Burst Monitor (GBM) on-board the Fermi satellite to search for sterile neutrino decay lines in the energy range 10-25 keV corresponding to sterile neutrino mass range 20-50 keV. This energy range has been out of reach of traditional X-ray satellites such as Chandra, Suzaku, XMM-Newton, and gamma-ray satellites such as INTEGRAL. Furthermore, the extremely wide field of view of the GBM opens a large fraction of the Milky Way dark matter halo to be probed. We start with 1601 days worth of GBM data, implement stringent data cuts, and perform two simple line search analyses on the reduced data: in the first, the line flux is limited without background modeling, and in the second, the background is modeled as a power-law. We find no significant excess lines in both our searches. We set new limits on sterile neutrino mixing angles, improving on previous limits by approximately an order of magnitude. Better understanding of detector and astrophysical backgrounds, as well as detector response, can further improve the limit.
The Earth Occultation Technique (EOT) has been applied to Fermi's Gamma-ray Burst Monitor (GBM) to perform all-sky monitoring for a predetermined catalog of hard X-ray/soft gamma-ray sources. In order to search for sources not in the catalog, thus completing the catalog and reducing a source of systematic error in EOT, an imaging method has been developed -- Imaging with a Differential filter using the Earth Occultation Method (IDEOM). IDEOM is a tomographic imaging method that takes advantage of the orbital precession of the Fermi satellite. Using IDEOM, all-sky reconstructions have been gene…
A combined BATSE-GBM hard X-ray catalog is presented based on Earth Occultation Imaging applied to a reanalysis of BATSE data. An imaging approach has been developed for the reanalysis of Earth Occultation analysis of BATSE data. The standard occultation analysis depends on a predetermined catalog of potential sources, so that a real source not present in the catalog may induce systematic errors when source counts associated with an uncatalogued source are incorrectly attributed to catalog sources. The goal of the imaging analysis is to find a complete set of hard X-ray sources, including sour…
Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog enters or exits occultation by the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors and spanning 150 keV to 40 MeV for the GBM BGO detectors. Our preliminary catalog consists of galactic X-ray binaries, the Crab Nebula, and active galactic nuclei. In addition, to Earth occultat…
Employing the 12 NaI detectors in the Fermi GBM, the Earth Occultation Technique (EOT) can be used to measure the fluxes of x-ray and gamma-ray sources. Each time a source passes behind the Earth (or emerges from behind the Earth), a step-like feature is produced in the detector count rate. With a predefined catalog of source positions, the times of the occultation steps can be calculated, the individual steps fit, and the fluxes derived. However, in order to find new sources and generate a complete catalog, a method is needed for generating an image of the sky. An imaging algorithm has been d…
The Fermi Gamma Ray Burst Monitor (GBM) is an all sky gamma-ray monitor well known in the gamma-ray burst community. Although GBM excels in detecting the hard, bright extragalactic GRBs, its sensitivity above 8 keV and all-sky view make it an excellent instrument for the detection of rare, short-lived Galactic transients. In March 2010, we initiated a systematic search for transients using GBM data. We conclude this phase of the search by presenting a 3 year catalog of 1084 X-ray bursts. Using spectral analysis, location and spatial distributions we classified the 1084 events into 752 thermonu…
The NaI and BGO detectors on the Gamma ray Burst Monitor (GBM) on Fermi are now being used for long term monitoring of the hard X-ray/low energy gamma ray sky. Using the Earth occultation technique demonstrated previously by the BATSE instrument on the Compton Gamma Ray Observatory, GBM produces multiband light curves and spectra for known sources and transient outbursts in the 8 keV - 1 MeV band with its NaI detectors and up to 40 MeV with its BGO. Coverage of the entire sky is obtained every two orbits, with sensitivity exceeding that of BATSE at energies below ~25 keV and above ~1.5 MeV. We…
The NaI and BGO detectors on the Gamma-ray Burst Monitor (GBM) on Fermi are now being used for long-term monitoring of the hard X-ray/low energy gamma-ray sky. Using the Earth occultation technique as demonstrated previously by the BATSE instrument on the Compton Gamma-Ray Observatory, GBM can be used to produce multiband light curves and spectra for known sources and transient outbursts in the 8 keV to 1 MeV energy range with its NaI detectors and up to 40 MeV with its BGO detectors. Over 85% of the sky is viewed every orbit, and the precession of the Fermi orbit allows the entire sky to be v…
The Gamma ray Burst Monitor (GBM) on board Fermi has been providing continuous data to the astronomical community since 2008 August 12. In this paper we present the results of the analysis of the first three years of these continuous data using the Earth occultation technique to monitor a catalog of 209 sources. From this catalog, we detect 99 sources, including 40 low-mass X-ray binary/neutron star systems, 31 high-mass X-ray binary neutron star systems, 12 black hole binaries, 12 active galaxies, 2 other sources, plus the Crab Nebula, and the Sun. Nine of these sources are detected in the 10…
We review more than 10 years of continuous monitoring of accreting X-ray pulsars with the all-sky Gamma-ray Burst Monitor (GBM) aboard the Fermi Gamma-ray Space Telescope. Our work includes data from the start of GBM operations in August 2008, through to November 2019. Pulsations from 39 accreting pulsars are observed over an energy range of $10-50\,$keV by GBM. The GBM Accreting Pulsars Program (GAPP) performs data reduction and analysis for each accreting pulsar and makes histories of the pulse frequency and pulsed flux publicly available. We examine in detail the spin histories, outbursts a…
We present the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger event GW151226 and candi- date LVT151012. No candidate electromagnetic counterparts were detected by either the GBM or LAT. We present a detailed analysis of the GBM and LAT data over a range of timescales from seconds to years, using automated pipelines and new techniques for char- acterizing the upper limits across a large area of the sky. Due to the partial GBM and LAT coverage of the large LIGO localization regions at the trigger times for both events, dif- fe…
The Gamma ray Burst Monitor (GBM) on board Fermi Gamma-ray Space Telescope has been providing continuous data to the astronomical community since 2008 August 12. We will present the results of the analysis of the first three years of these continuous data using the Earth occultation technique to monitor a catalog of 209 sources. Although the occultation technique is in principle quite simple, in practice there are many complications including the dynamic instrument response, source confusion, and scattering in the Earth's atmosphere, which will be described. We detect 99 sources, including 40 …
The secondary instrument onboard Fermi, the Gamma-ray Burst Monitor (GBM) is an all sky monitor consisting of 14 scintillation detectors. When analysing transient events such as Gamma-Ray Bursts (GRBs) and Solar Flares (SFs) the background is usually modelled as a polynomial (order 0-4). However, for long events the background may vary more than can be accounted for with a simple polynomial. In these cases a more accurate knowledge of GBM's background rates is required. Here we present an alternative method of both determining the background and distinguishing low-level emission from the instr…
We study the relation between luminosity and spin-period change in X-ray binary pulsars using long-term light curve obtained by the MAXI/GSC all-sky survey and pulse period data from the Fermi/GBM pulsar project. X-ray binaries, consisting of a highly magnetized neutron star and a stellar companion, originate X-ray emission according to the energy of the accretion matter onto the neutron star. The accretion matter also transfers the angular momentum at the Alfven radius, and then spin up the neutron star. Therefore, the X-ray luminosity and the spin-up rate are supposed to be well correlated. …
The Advanced LIGO and Advanced Virgo ground-based gravitational-wave detectors are projected to come online 2015-2016, reaching a final sensitivity sufficient to observe dozens of binary neutron star mergers per year by 2018. We present a fully-automated, targeted search strategy for prompt gamma-ray counterparts in offline Fermi-GBM data. The multi-detector method makes use of a detailed model response of the instrument, and benefits from time and sky location information derived from the gravitational-wave signal.
To observationally study spin-period changes of accreting pulsars caused by the accretion torque, the present work analyzes X-ray light curves of 12 Be binary pulsars obtained by the MAXI/GSC all-sky survey and their pulse periods measured by the Fermi/GBM pulsar project, both covering more than 6 years from 2009 August to 2016 March. The 12 objects were selected because they are accompanied by clear optical identification, and accurate measurements of surface magnetic fields. The luminosity $L$ and the spin-frequency derivatives $\dotν$, measured during large outbursts with $L\gtrsim 1\times …
In order to discern the physical nature of many gamma-ray sources in the sky, we must look not only in spectral and spatial dimensions, but also understand their temporal variability. However, timing analysis of sources with a highly transient nature, such as magnetar bursts, is difficult: standard Fourier techniques developed for long-term variability generally observed, for example, from AGN often do not apply. Here, we present newly developed timing methods applicable to transient events of all kinds, and show their successful application to magnetar bursts observed with Fermi/GBM. Magnetar…
We investigate for the first time the potential of angular auto- and cross-correlation power spectra in identifying sterile neutrino dark matter in the cosmic X-ray background. We take as reference the performance of the soon-to-be-launched eROSITA satellite. The main astrophysical background sources against sterile neutrino decays are active galactic nuclei, galaxies powered by X-ray binaries, and clusters of galaxies. While sterile neutrino decays are always subdominant in the auto-correlation power spectra, they can be efficiently enhanced when cross-correlating with tracers of the dark mat…
Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We …
With an instantaneous view of 70% of the sky, the Fermi Gamma-ray Burst Monitor (GBM) is an excellent partner in the search for electromagnetic counterparts to gravitational wave (GW) events. GBM observations at the time of the Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914 reveal the presence of a weak transient above 50 keV, 0.4~s after the GW event, with a false alarm probability of 0.0022 (2.9$σ$). This weak transient lasting 1 s was not detected by any other instrument and does not appear connected with other previously known astrophysical, solar, terrestrial, o…
The Fermi Gamma-ray Space Telescope, a key mission in multiwavelength and multimessenger studies, has been surveying the gamma-ray sky from its low-Earth orbit since 2008. Its two scientific instruments, the Gamma-ray Burst Monitor (GBM) and the Large Area Telescope (LAT), cover 8 orders of magnitude in photon energy. The GBM consists of 12 Sodium Iodide detectors and 2 Bismuth Germinate detectors, covering the 10 keV - 40 MeV energy range, arrayed on two sides of the spacecraft so as to view the entire sky that is not occulted by the Earth. The LAT is a pair production telescope based on sili…
The supporting instrument on board the Fermi Gamma-ray Space Telescope, the Gamma-ray Burst Monitor (GBM) is a wide-field gamma-ray monitor composed of 14 individual scintillation detectors, with a field of view which encompasses the entire unocculted sky. Primarily designed as transient monitors, the conventional method for background determination with GBM-like instruments is to time interpolate intervals before and after the source as a polynomial. This is generally sufficient for sharp impulsive phenomena such as Gamma-Ray Bursts (GRBs) which are characterised by impulsive peaks with sharp…
The sky distribution of Gamma-Ray Bursts (GRBs) has been intensively studied by various groups for more than two decades. Most of these studies test the isotropy of GRBs based on their sky number density distribution. In this work we propose an approach to test the isotropy of the Universe through inspecting the isotropy of the properties of GRBs such as their duration, fluences and peak fluxes at various energy bands and different time scales. We apply this method on the {\em Fermi} / Gamma-ray Burst Monitor (GBM) data sample containing 1591 GRBs. The most noticeable feature we found is near …
Gamma-ray bursts (GRBs) were confirmed to be of extragalactic origin due to their isotropic angular distribution, combined with the fact that they exhibited an intensity distribution that deviated strongly from the $-3/2$ power law. This finding was later confirmed with the first redshift, equal to at least $z=0.835$, measured for GRB970508. Despite this result, the data from $CGRO$/BATSE and $Swift$/BAT indicate that long GRBs are indeed distributed isotropically, but the distribution of short GRBs is anisotropic. $Fermi$/GBM has detected 1669 GRBs up to date, and their sky distribution is ex…
We present a method for determining the background of Fermi GBM GRBs using the satellite positional information and a physical model. Since the polynomial fitting method typically used for GRBs is generally only indicative of the background over relatively short timescales, this method is particularly useful in the cases of long GRBs or those which have Autonomous Repoint Request (ARR) and a background with much variability on short timescales. We give a Direction Dependent Background Fitting (DDBF) method for separating the motion effects from the real data and calculate the duration (T90 and…
The monitor of all-sky X-ray image (MAXI) Gas Slit Camera (GSC) on the International Space Station (ISS) detected a gamma-ray burst (GRB) on 2009, September 26, GRB\,090926B. This GRB had extremely hard spectra in the X-ray energy range. Joint spectral fitting with the Gamma-ray Burst Monitor on the Fermi Gamma-ray Space Telescope shows that this burst has peculiarly narrow spectral energy distribution and is represented by Comptonized blackbody model. This spectrum can be interpreted as photospheric emission from the low baryon-load GRB fireball. Calculating the parameter of fireball, we foun…
Thermonuclear bursts from slowly accreting neutron stars (NSs) have proven difficult to detect, yet they are potential probes of the thermal properties of the neutron star interior. During the first year of a systematic all-sky search for X-ray bursts using the Gamma-ray Burst Monitor (GBM) aboard the Fermi Gamma-ray Space Telescope we have detected 15 thermonuclear bursts from the NS low-mass X-ray binary 4U 0614+09, when it was accreting at nearly 1% of the Eddington limit. We measured an average burst recurrence time of 12+/-3 d (68% confidence interval) between March 2010 and March 2011, c…
A Multi-Mission Detection Framework for High-Energy Transients: Application to a 13-year Fermi/GBM and Swift/BAT Sample
Weizmann Institute of Science（魏茨曼科学研究所）；University of California at Santa Barbara（加州大学圣塔芭芭拉分校）；International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（塔塔基础研究院国际理论科学中心）
The ANITA balloon experiment has recently observed several ~EeV cascade events at an angle below the horizon that renders any Standard Model (SM) interpretation unlikely as the Earth is significantly opaque to all SM particles at such energies. In this paper, we study a sterile neutrino interpretation of these events, calculating the angular acceptance of cascades and the relative sensitivities of several experiments to a cascade initiated by an EeV sterile neutrino. We find that ANITA is uniquely sensitive to this type of upward directed cascade signal over a wide portion of the sky and from …
All-sky monitors can measure the fluxes of astrophysical sources by measuring the changes in observed counts as the source is occulted by the Earth. Such measurements have typically been carried out by all-sky monitors like $\textit{CGRO}$-BATSE and $\textit{Fermi}$-GBM. We demonstrate for the first time the application of this technique to measure fluxes of sources using a collimated instrument: the Cadmium Zinc Telluride detector on $\textit{AstroSat}$. Reliable flux measurements are obtained for the Crab nebula and pulsar, and for Cyg X-1 by carefully selecting the best occultation data set…
We present two complementary NuSTAR x-ray searches for keV-scale dark matter decaying to mono-energetic photons in the Milky Way halo. In the first, we utilize the known intensity pattern of unfocused stray light across the detector planes -- the dominant source of photons from diffuse sources -- to separate astrophysical emission from internal instrument backgrounds using ${\sim}$7-Ms/detector deep blank-sky exposures. In the second, we present an updated parametric model of the full NuSTAR instrument background, allowing us to leverage the statistical power of an independent ${\sim}$20-Ms/de…
On 2009 June 5, the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray Space Telescope triggered on two short, and relatively dim bursts with spectral properties similar to Soft Gamma Repeater (SGR) bursts. Independent localizations of the bursts by triangulation with the Konus-RF and with the Swift satellite, confirmed their origin from the same, previously unknown, source. The subsequent discovery of X-ray pulsations with the Rossi X-ray Timing Explorer (RXTE), confirmed the magnetar nature of the new source, SGR J0418+5729. We describe here the Fermi/GBM observations, the discovery a…
We present two different search methods for electromagnetic counterparts to gravitational-wave (GW) events from ground-based detectors using archival NASA high-energy data from the Fermi-GBM and RXTE-ASM instruments. To demonstrate the methods, we use a limited number of representative GW background noise events produced by a search for binary neutron star coalescence over the last two months of the LIGO-Virgo S6/VSR3 joint science run. Time and sky location provided by the GW data trigger a targeted search in the high-energy photon data. We use two custom pipelines: one to search for prompt g…
We present the results of the search for decaying dark matter with particle mass in the 6-40 keV range with NuSTAR deep observations of COSMOS and ECDFS empty sky fields. We show that main contribution to the decaying dark matter signal from the Milky Way galaxy comes through the aperture of the NuSTAR detector, rather than through the focusing optics. High sensitivity of the NuSTAR detector, combined with the large aperture and large exposure times of the two observation fields allow us to improve previously existing constraints on the dark matter decay time by up to an order of magnitude in …
The LIGO and Virgo scientific collaboration (LVC) alerted two binary neutron star (BNS) merger candidates, S190425z and S190426c. Fermi-GBM observed 55.6\% (for S190425z) and 100\% (for S190426c) of the probability regions of both events at the respective merger times, but no gamma-ray burst (GRB) was detected in either case. The derived luminosity upper limits suggest that a short GRB similar to GRB 170817A would not be detectable for both cases due to their larger distances than GW170817. Assuming that the jet profile obtained from the GW170817/GRB 170817A is quasi-universal for all BNS-GRB …
Sterile neutrinos with masses in the keV range are well-motivated extensions to the Standard Model that could explain the observed neutrino masses while also making up the dark matter (DM) of the Universe. If sterile neutrinos are DM then they may slowly decay into active neutrinos and photons, giving rise to the possibility of their detection through narrow spectral features in astrophysical X-ray data sets. In this work, we perform the most sensitive search to date for this and other decaying DM scenarios across the mass range from 5 to 16 keV using archival XMM-Newton data. We reduce 547 Ms…
17 Yr of Magnetar Bursts Observed with the Fermi Gamma-ray Burst Monitor
University of Alabama in Huntsville（亨茨维尔阿拉巴马大学）；Sabancı University, Faculty of Engineering and Natural Sciences（萨班哲大学工程与自然科学学院）；Beijing Normal University（北京师范大学）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学天文与前沿科学研究院）；Universities Space and Research Association（大学空间研究协会）；University of Galway（高威大学）；Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville（亨茨维尔阿拉巴马大学空间等离子体与高空大气研究中心）；Rice University（莱斯大学）
We present a scheme to determine the spectral state of the canonical black hole Cyg X-1 using data from previous and current X-ray all sky monitors (RXTE-ASM, Swift-BAT, MAXI, and Fermi-GBM). State determinations of the hard/intermediate and soft state agree to better than 10% between different monitors, facilitating the determination of the state and its context for any observation of the source, potentially over the lifetimes of different individual monitors. A separation of the hard and the intermediate state, which strongly differ in their spectral shape and short-term timing behavior, is …
Dark matter might be made of "warm" particles, such as sterile neutrinos in the keV mass range, which can decay into photons through mixing and are consequently detectable by X-ray telescopes. Axionlike particles (ALPs) are detectable by X-ray telescopes too when coupled to standard model particles and decay into photons in the keV range. Both particles could explain the unidentified 3.5 keV line and, interestingly, XENON1T observed an excess of electron recoil events most prominent at 2-3 keV. One explanation could be an ALPs origin, which is not yet excluded by X-ray constraints in an anomal…
We report results of a spectral and timing analysis of the poorly studied transient X-ray pulsar 2S 1553-542 using data collected with the NuSTAR and Chandra observatories and the Fermi/GBM instrument during an outburst in 2015. Properties of the source at high energies (>30 keV) are studied for the first time and the sky position had been essentially improved. The source broadband spectrum has a quite complicated shape and can be reasonably described by a composite model with two continuum components - a black body emission with the temperature about 1 keV at low energies and a power law with…
We describe an improved method of mapping the gamma-ray sky by applying the Linear Radon Transform to data from BATSE on NASA's CGRO. Based on a method similar to that used in medical imaging, we use the relatively sharp (~0.25 deg) limb of the Earth to collimate BATSE's eight Large Area Detectors (LADs). Coupling this to the ~51-day precession cycle of the CGRO orbit, we can complete a full survey of the sky, localizing point sources to < 1 deg accuracy. This technique also uses a physical model for removing many sources of gamma-ray background, which allows us to image strong gamma-ray sourc…
Following the faint gamma-ray burst, GRB 170817A, coincident with a gravitational wave-detected binary neutron star merger at $d\sim40$ Mpc, we consider the constraints on a local population of faint short duration GRBs (defined here broadly as $T_{90}<4$ s). We review proposed low-redshift short-GRBs and consider statistical limits on a $d\lessapprox200$ Mpc population using Swift/Burst Alert Telescope (BAT), Fermi/Gamma-ray Burst Monitor (GBM), and Compton Gamma-Ray Observatory (CGRO) Burst and Transient Source Experiment (BATSE) GRBs. Swift/BAT short-GRBs give an upper limit for the all-sky…
The Fermi Gamma-ray Space Telescope (Fermi) was launched on June 11, 2008 and began its first year sky survey on August 11, 2008. The Large Area Telescope (LAT), a wide field-of-view pair-conversion telescope covering the energy range from 20 MeV to more than 300 GeV, is the primary instrument on Fermi. While this review focuses on results obtained with the LAT, the Gamma-ray Burst Monitor (GBM) complements the LAT in its observations of transient sources and is sensitive to X-rays and gamma-rays with energies between 8 keV and 40 MeV. During the first year in orbit, the Fermi LAT has observed…
Observations of nearby galaxies and galaxy clusters have reported an unexpected X-ray emission line around 3.5 kilo-electron volts (keV). Proposals to explain this line include decaying dark matter$-$in particular, that the decay of sterile neutrinos with a mass around 7 keV could match the available data. If this interpretation is correct, the 3.5 keV line should also be emitted by dark matter in the halo of the Milky Way. We used more than 30 megaseconds of XMM-Newton (X-ray Multi-Mirror Mission) blank-sky observations to test this hypothesis, finding no evidence of the 3.5-keV line emission…
GRB 210121A was observed by Insight-HXMT, Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM), Fermi Gamma-ray Burst Monitor (Fermi/GBM) on Jan 21st 2021. In this work, photospheric emission from a structured jet is preferred to interpret the prompt emission phase of GRB 210121A and emissions from different regimes are observed on-axis. Particularly, the emission from the intermediate photosphere is first observed in the first 1.3 s of the prompt emission, while those from the other part are dominant by the saturated regime, and offers an alternative explanation …
The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to $\sim$ 40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the search for optical counterparts a challenging endeavour. We have developed and executed an extensive program with the wide field of view of the Zwicky Transient Facility (ZTF) camera, mounted on the Palomar 48 inch Oschin telescope (P48), to perform target-of-opportunity (ToO) observations on 10 Fermi-GBM SGRBs during 2018 and 2020-2021. Bridging the large sky areas with small field of view optical telescopes in orde…
We present a comprehensive search for the 3.5 keV line, using $\sim$51 Ms of archival Chandra observations peering through the Milky Way's Dark Matter Halo from across the entirety of the sky, gathered via the Chandra Source Catalog Release 2.0. We consider the data's radial distribution, organizing observations into four data subsets based on angular distance from the Galactic Center. All data is modeled using both background-subtracted and background-modeled approaches to account for the particle instrument background, demonstrating statistical limitations of the currently-available $\sim$1 …
The birth of gravitational-wave / electromagnetic astronomy was heralded by the joint observation of gravitational waves (GWs) from a binary neutron star (BNS) merger by Advanced LIGO and Advanced Virgo, GW170817, and of gamma-rays from the short gamma-ray burst GRB170817A by the Fermi Gamma-ray Burst Monitor (GBM) and INTEGRAL. This detection provided the first direct evidence that at least a fraction of BNSs are progenitors of short GRBs. GRBs are now also known to emit very-high-energy (VHE, > 100 GeV) photons as has been shown by recent independent detections of the GRBs 1901114C and 18072…
Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint S…
