Catalog Of Gamma-ray Bursts Research Articles

Prospects of Observing Gamma-Ray Bursts with Orbital Detectors of Ultra-High-Energy Cosmic Rays

TUS (Tracking Ultraviolet Set-up), the first orbital telescope of ultra-high energy cosmic rays (UHECRs), has demonstrated that instruments of this kind have much broader capabilities and can also detect meteors, transient luminous events, anthropogenic glow and other processes taking place in Earth atmosphere in the UV frequency range. In this short letter, we address the question if an orbital UHECR detector can also register gamma-ray bursts (GRBs) via the fluorescent glow of irradiated nocturnal atmosphere. An analysis of the Fermi GBM catalog of GRBs and properties of several active and perspective instruments reveals that a detector with parameters of the optical system similar to those of the KLYPVE-EUSO (K-EUSO) or POEMMA telescopes and an appropriate \slow-mode" trigger will be able to observe only two GRBs in average every year of operation. POEMMA will register up to 3-4 GRBs in a year of operation in the stereo mode.

The Konus–Wind Catalog of Gamma-Ray Bursts with Known Redshifts. II. Waiting-Mode Bursts Simultaneously Detected by Swift/BAT

Abstract In the second part of The Konus–Wind Catalog of Gamma-Ray Bursts with Known Redshifts (the first part: Tsvetkova et al. 2017; T17), we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected simultaneously by the Konus–Wind (KW) experiment (in the waiting mode) and by the Swift/BAT (BAT) telescope during the period from 2005 January to the end of 2018. By taking advantage of the high sensitivity of BAT and the wide spectral band of KW, we were able to constrain the peak spectral energies, the broadband energy fluences, and the peak fluxes for the joint KW–BAT sample of 167 weak, relatively soft GRBs (including four short bursts). Based on the GRB redshifts, which span the range 0.04 ≤ z ≤ 9.4, we estimate the rest frame, isotropic-equivalent energy, and peak luminosity. For 14 GRBs with reasonably constrained jet breaks, we provide the collimation-corrected values of the energetics. This work extends the sample of KW GRBs with known redshifts to 338 GRBs, the largest set of cosmological GRBs studied to date over a broad energy band. With the full KW sample, accounting for the instrumental bias, we explore GRB rest-frame properties, including hardness–intensity correlations, GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which we find to be in general agreement with those reported in T17 and other previous studies.

Forward Modeling of Double Neutron Stars: Insights from Highly Offset Short Gamma-Ray Bursts

Abstract We present a detailed analysis of two well-localized, highly offset short gamma-ray bursts—GRB 070809 and GRB 090515—investigating the kinematic evolution of their progenitors from compact object formation until merger. Calibrating to observations of their most probable host galaxies, we construct semi-analytic galactic models that account for star formation history and galaxy growth over time. We pair detailed kinematic evolution with compact binary population modeling to infer viable post-supernova velocities and inspiral times. By populating binary tracers according to the star formation history of the host and kinematically evolving their post-supernova trajectories through the time-dependent galactic potential, we find that systems matching the observed offsets of the bursts require post-supernova systemic velocities of hundreds of kilometers per second. Marginalizing over uncertainties in the stellar mass–halo mass relation, we find that the second-born neutron star in the GRB 070809 and GRB 090515 progenitor systems received a natal kick of at the and credible levels, respectively. Applying our analysis to the full catalog of localized short gamma-ray bursts will provide unique constraints on their progenitors and help unravel the selection effects inherent to observing transients that are highly offset with respect to their hosts.

GRB Fermi-LAT Afterglows: Explaining Flares, Breaks, and Energetic Photons

Abstract The Fermi-LAT collaboration presented the second gamma-ray burst (GRB) catalog covering its first 10 years of operations. A significant fraction of afterglow-phase light curves in this catalog cannot be explained by the closure relations of the standard synchrotron forward-shock model, suggesting that there could be an important contribution from another process. In view of the above, we derive the synchrotron self-Compton (SSC) light curves from the reverse shock in the thick- and thin-shell regime for a uniform-density medium. We show that this emission could explain the GeV flares exhibited in some LAT light curves. Additionally, we demonstrate that the passage of the forward shock synchrotron cooling break through the LAT band from jets expanding in a uniform-density environment may be responsible for the late time (≈102 s) steepening of LAT GRB afterglow light curves. As a particular case, we model the LAT light curve of GRB 160509A that exhibited a GeV flare together with a break in the long-lasting emission, and also two very high energy photons with energies of 51.9 and 41.5 GeV observed 76.5 and 242 s after the onset of the burst, respectively. Constraining the microphysical parameters and the circumburst density from the afterglow observations, we show that the GeV flare is consistent with an SSC reverse-shock model, the break in the long-lasting emission with the passage of the synchrotron cooling break through the Fermi-LAT band, and the very energetic photons with SSC emission from the forward shock, when the outflow carries a significant magnetic field (R B ≃ 30) and it decelerates in a uniform-density medium with a very low density ( ).

The Fourth Fermi-GBM Gamma-Ray Burst Catalog: A Decade of Data

Abstract We present the fourth in a series of catalogs of gamma-ray bursts (GRBs) observed with Fermi’s Gamma-ray Burst Monitor (Fermi-GBM). It extends the six year catalog by four more years, now covering the 10 year time period from trigger enabling on 2008 July 12 to 2018 July 11. During this time period GBM triggered almost twice a day on transient events, 2356 of which we identified as cosmic GRBs. Additional trigger events were due to solar flare events, magnetar burst activities, and terrestrial gamma-ray flashes. The intention of the GBM GRB catalog series is to provide updated information to the community on the most important observables of the GBM-detected GRBs. For each GRB the location and main characteristics of the prompt emission, the duration, peak flux, and fluence are derived. The latter two quantities are calculated for the 50–300 keV energy band, where the maximum energy release of GRBs in the instrument reference system is observed and also for a broader energy band from 10–1000 keV, exploiting the full energy range of GBM’s low-energy detectors. Furthermore, information is given on the settings of the triggering criteria and exceptional operational conditions during years 7 to 10 in the mission. This fourth catalog is an official product of the Fermi-GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

Revisiting the statistical isotropy of GRB sky distribution

ABSTRACT The assumption of homogeneity and isotropy on large scales is one of the main hypotheses of the standard cosmology. In this paper, we test the hypothesis of isotropy from the two-point angular correlation function of 2626 gamma-ray bursts (GRB) of the FERMI GRB catalogue. We show that the uncertainties in the GRB positions induce spurious anisotropic signals in their sky distribution. However, when such uncertainties are taken into account no significant evidence against the large-scale statistical isotropy is found. This result remains valid even for the sky distribution of short-lived GRB, contrarily to previous reports.

Closure Relations of Gamma-Ray Bursts in High Energy Emission

The synchrotron external shock model predicts the evolution of the spectral ($\beta$) and temporal ($\alpha$) indices during the gamma-ray burst (GRB) afterglow for different environmental density profiles, electron spectral indices, electron cooling regimes, and regions of the spectrum. We study the relationship between $\alpha$ and $\beta$, the so-called "closure relations" with GRBs detected by \textit{Fermi} Large Area Telescope (\textit{Fermi}-LAT) from 2008 August to 2018 August. The spectral and temporal indices for the > 100 MeV emission from the \textit{Fermi}-LAT as determined in the Second Fermi-LAT Gamma-ray Burst Catalog (2FLGC) are used in this work. We select GRBs whose spectral and temporal indices are well constrained (58 long-duration GRBs and 1 short-duration GRBs) and classify each GRB into the best-matched relation. As a result, we found that a number of GRBs require a very small fraction of the total energy density contained in the magnetic field ($\epsilon_{B}$ $\lesssim$ 10$^{-7}$). The estimated mean and standard deviation of electron spectral index $\mathit{p}$ are 2.40 and 0.44, respectively. The GRBs satisfying a closure relation of the slow cooling tend to have a softer $\mathit{p}$ value compared to those of the fast cooling. Moreover, the Kolmogorov--Smirnov test of the two $\mathit{p}$ distributions from the fast and slow coolings rejects a hypothesis that the two distributions are drawn from the single reference distribution with a significance of 3.2 $\sigma$. Lastly, the uniform density medium is preferred over the medium that decreases like the inverse of distance squared for long-duration GRBs.

A Decade of Gamma-Ray Bursts Observed by Fermi-LAT: The Second GRB Catalog

Abstract The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present the second catalog of LAT-detected GRBs, covering the first 10 yr of operations, from 2008 to 2018 August 4. A total of 186 GRBs are found; of these, 91 show emission in the range 30–100 MeV (17 of which are seen only in this band) and 169 are detected above 100 MeV. Most of these sources were discovered by other instruments (Fermi/GBM, Swift/BAT, AGILE, INTEGRAL) or reported by the Interplanetary Network (IPN); the LAT has independently triggered on four GRBs. This catalog presents the results for all 186 GRBs. We study onset, duration, and temporal properties of each GRB, as well as spectral characteristics in the 100 MeV–100 GeV energy range. Particular attention is given to the photons with the highest energy. Compared with the first LAT GRB catalog, our rate of detection is significantly improved. The results generally confirm the main findings of the first catalog: the LAT primarily detects the brightest GBM bursts, and the high-energy emission shows delayed onset as well as longer duration. However, in this work we find delays exceeding 1 ks and several GRBs with durations over 10 ks. Furthermore, the larger number of LAT detections shows that these GRBs not only cover the high-fluence range of GBM-detected GRBs but also sample lower fluences. In addition, the greater number of detected GRBs with redshift estimates allows us to study their properties in both the observer and rest frames. Comparison of the observational results with theoretical predictions reveals that no model is currently able to explain all results, highlighting the role of LAT observations in driving theoretical models.

Update on testing the isotropy of the properties of gamma-ray bursts

Abstract Previously, we proposed a novel method to inspect the isotropy of the properties of gamma-ray bursts (GRBs), such as their duration, fluences and peak fluxes at various energy bands and different time-scales, complementary to existing studies of the spatial distribution of GRBs by other authors. The method was then applied to the Fermi Gamma-ray Burst Monitor (GBM) Burst Catalog containing 1591 GRBs. Except for one particular direction where we noticed some hints of violation from statistical isotropy, the rest of the data showed consistency with isotropy. In this work, we apply our method, with some minor modifications, to the updated Fermi GBM data sample containing 2266 GRBs, which is thus ∼40 per cent larger. We also test two other major GRB catalogues: the Burst And Transient Source Experiment (BATSE) Current GRB Catalog of the Compton Gamma Ray Observatory (CGRO), containing ∼2000 bursts, and the Swift Burst Alert Telescope (BAT) GRB Catalog, containing ∼1200 bursts. The new results using the updated data are consistent with our previous findings and we find no statistically significant anisotropic feature in the observed properties of these samples of all GRBs.

On the α–intensity correlation in gamma-ray bursts: subphotospheric heating with varying entropy

The emission mechanism during the prompt phase in gamma-ray bursts (GRBs) can be investigated through correlations between spectral properties. Here, we revisit the correlation relating the instantaneous flux, $F$, and the photon index below the spectral break, $\alpha$, in individual emission pulses, by studying the 38 most prominent pulses in the Fermi/GBM GRB catalogue. First, we search for signatures of the bias in the determination of $\alpha$ due to the limited spectral coverage (window effect) expected in the synchrotron case. The absence of such a characteristic signature argues against the simplest synchrotron models. We instead find that the observed correlation between $F$ and $\alpha$ can, in general, be described by the relation $F(t) \propto {\rm e}^{k\,\alpha(t)}$, for which the median $k = 3$. We suggest that this correlation is a manifestation of subphotospheric heating in a flow with a varying entropy. Around the peak of the light curve, a large entropy causes the photosphere to approach the saturation radius, leading to an intense emission with a narrow spectrum. As the entropy decreases the photosphere secedes from the saturation radius, and weaker emission with a broader spectrum is expected. This simple scenario naturally leads to a correlated variation of the intensity and spectral shape, covering the observed range.

Statistical Study of the Swift X-Ray Flash and X-Ray Rich Gamma-Ray Bursts

Abstract We build a comprehensive sample to statistically describe the properties of X-ray flashes (XRFs) and X-ray riches (XRRs) from the third Swift Burst Alert Telescope (BAT3) catalog of Gamma-ray bursts (GRBs). We obtain 81 XRFs, 540 XRRs, and 394 classical GRBs (C-GRBs). We statistically explore the different properties of the γ-ray prompt emission, the X-ray emission, the X-ray light-curve type, the association with supernovae (SNe), and the host galaxy properties for these sources. We confirm that most XRFs/XRRs are long GRBs with low values of peak energy and they are low-luminosity GRBs. XRFs, XRRs, and C-GRBs follow the same E X,iso–E γ,iso–E peak,z correlations. Compared to the classical GRBs, XRFs are favorable to have the association with SN explosions. We do not find any significant differences of redshift distribution and host galaxy properties among XRFs, XRRs, and C-GRBs. We also discuss some observational biases and selection effects that may affect our statistical results. The GRB detectors with wide energy range and low energy threshold are expected for the XRF/XRR research in the future.

The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts. I. Bursts Detected in the Triggered Mode

Abstract In this catalog, we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected in the triggered mode of the Konus-Wind (KW) experiment during the period from 1997 February to 2016 June. The sample consists of 150 GRBs (including 12 short/hard bursts) and represents the largest set of cosmological GRBs studied to date over a broad energy band. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with two model functions, the total energy fluences, and the peak energy fluxes. Based on the GRB redshifts, which span the range , we estimate the rest-frame, isotropic-equivalent energy, and peak luminosity. For 32 GRBs with reasonably constrained jet breaks, we provide the collimation-corrected values of the energetics. We consider the behavior of the rest-frame GRB parameters in the hardness–duration and hardness–intensity planes, and confirm the “Amati” and “Yonetoku” relations for Type II GRBs. The correction for the jet collimation does not improve these correlations for the KW sample. We discuss the influence of instrumental selection effects on the GRB parameter distributions and estimate the KW GRB detection horizon, which extends to , stressing the importance of GRBs as probes of the early universe. Accounting for the instrumental bias, we estimate the KW GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which are in general agreement with those obtained in previous studies.

The InterPlanetary Network Supplement to the Second Fermi GBM Catalog of Cosmic Gamma-Ray Bursts

Abstract InterPlanetary Network (IPN) data are presented for the gamma-ray bursts in the second Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 462 bursts in that catalog between 2010 July 12 and 2012 July 11, 428, or 93%, were observed by at least 1 other instrument in the 9-spacecraft IPN. Of the 428, the localizations of 165 could be improved by triangulation. For these bursts, triangulation gives one or more annuli whose half-widths vary between about 2.′3° and 16°, depending on the peak flux, fluence, time history, arrival direction, and the distance between the spacecraft. We compare the IPN localizations with the GBM 1σ, 2σ, and 3σ error contours and find good agreement between them. The IPN 3σ error boxes have areas between about 8 square arcminutes and 380 square degrees, and are an average of 2500 times smaller than the corresponding GBM 3σ localizations. We identify four bursts in the IPN/GBM sample whose origins were given as “uncertain,” but may in fact be cosmic. This leads to an estimate of over 99% completeness for the GBM catalog.

The Fermi-GBM Gamma-Ray Burst Catalogs: The First Six Years

Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two gamma-ray bursts (GRBs) every three days. Here we present the main results from the latest two catalogs provided by the Fermi-GBM science team, namely the third GBM GRB catalog [1] and the first GBM time-resolved spectral catalog [2]. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM detected bursts. It comprises 1405 triggers identified as GRBs. For each one, location and main characteristics of the prompt emission, the duration, the peak flux and the fluence are derived. The GBM time-resolved spectral catalog presents high-quality time-resolved spectral analysis with high temporal and spectral resolution of the brightest bursts observed by Fermi GBM in a shorter period than the former catalog, namely four years. It comprises 1491 spectra from 81 bursts. Distributions of parameters, statistics of the parameter populations, parameter-parameter and parameter-uncertainty correlations, and their exact values are obtained.

Possible gamma-ray burst radio detections by the Square Kilometre Array. New perspectives

The next generation interferometric radio telescope, the Square Kilometre Array (SKA), which will be the most sensitive and largest radio telescope ever constructed, could greatly contribute to the detection, survey and characterization of Gamma Ray Bursts (GRBs). By the SKA, it will be possible to perform the follow up of GRBs even for several months. This approach would be extremely useful to extend the Spectrum Energetic Distribution (SED) from the gamma to the to radio band and would increase the number of radio detectable GRBs. In principle, the SKA could help to understand the physics of GRBs by setting constraints on theoretical models. This goal could be achieved by taking into account multiple observations at different wavelengths in order to obtain a deeper insight of the sources. Here, we present an estimation of GRB radio detections, showing that the GRBs can really be observed by the SKA. The approach that we present consists in determining blind detection rates derived by a very large sample consisting of merging several GRB catalogues observed by current missions as Swift, Fermi, Agile and INTEGRAL and by previous missions as BeppoSAX, CGRO, GRANAT, HETE-2, Ulysses and Wind. The final catalogue counts 7516 distinct sources. We compute the fraction of GRBs that could be observed by the SKA at high and low frequencies, above its observable sky. Considering the planned SKA sensitivity and through an extrapolation based on previous works and observations, we deduce the minimum fluence in the range 15-150 keV. This is the energy interval where a GRB should emit to be detectable in the radio band by the SKA. Results seem consistent with observational capabilities.

THE THIRD FERMI GBM GAMMA-RAY BURST CATALOG: THE FIRST SIX YEARS

ABSTRACT Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two γ-ray bursts (GRBs) every three days. Here, we present the third of a series of catalogs of GRBs detected by GBM, extending the second catalog by two more years through the middle of 2014 July. The resulting list includes 1405 triggers identified as GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM-detected GRBs. For each GRB, the location and main characteristics of the prompt emission, the duration, peak flux, and fluence are derived. The latter two quantities are calculated for the 50–300 keV energy band where the maximum energy release of GRBs in the instrument reference system is observed, and also for a broader energy band from 10 to 1000 keV, exploiting the full energy range of GBM's low-energy [Nai[Tl)] detectors. Using statistical methods to assess clustering, we find that the hardness and duration of GRBs are better fit by a two-component model with short-hard and long-soft bursts than by a model with three components. Furthermore, information is provided on the settings and modifications of the triggering criteria and exceptional operational conditions during years five and six in the mission. This third catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

NEAR-EXTREMAL BLACK HOLES AS INITIAL CONDITIONS OF LONG GRB SUPERNOVAE AND PROBES OF THEIR GRAVITATIONAL WAVE EMISSION

Long gamma-ray bursts (GRBs) associated with supernovae and short GRBs with extended emission (SGRBEE) from mergers are probably powered by black holes as a common inner engine, as their prompt GRB emission satisfies the same Amati correlation in the Ep,i–Eiso plane. We introduce modified Bardeen equations to identify hyper-accretion driving newly formed black holes in core-collapse supernovae to near-extremal spin as a precursor to prompt GRB emission. Subsequent spin-down is observed in the BATSE catalog of long GRBs. Spin-down provides a natural unification of long durations associated with the lifetime of black hole spin for normal long GRBs and SGRBEEs, given the absence of major fallback matter in mergers. The results point to major emissions unseen in high frequency gravitational waves. A novel matched filtering method is described for LIGO–Virgo and KAGRA broadband probes of nearby core-collapse supernovae at essentially maximal sensitivity.

OBSERVATION OF MUON EXCESS AT GROUND LEVEL IN RELATION TO GAMMA-RAY BURSTS DETECTED FROM SPACE

In this paper we examine the possibility of the ground observation of the gigaelectronvolt counterparts associated with the Monitor of All-sky X-ray Image transient event (trigger 58072727) and the Swift GRB140512A event. In both cases, there was a muon excess with a statistical significance above 4σ. The coordinates of the events were located in the field of view (FOV) of the Tupi muon telescopes at the time of the occurrence. Since 2013 August, the Tupi experiment has been operating a new extended array of five muon telescopes, located at ground level at (, 3 m above sea level). This location coincides with the South Atlantic Anomaly central region. We consider a hypothesis that the muon excess could be due to photonuclear reactions in the Earth's atmosphere induced by gamma rays with energies above 10 GeV. We describe a data analysis for candidate events identified by internally triggered (by the Tupi experiment) as well as untriggered (dependent on external observations) modes of search. In light of the Fermi LAT () gamma-ray bursts (GRBs) catalog, we examine the possibility of the ground observation of similar transient events within the FOV of the extended Tupi array and perform a systematic analysis of the Tupi data. Using a Monte Carlo simulation, we discuss the experimental conditions that allow the detection of signals from GRBs at ground level.

Search for low-energy neutrinos from gamma-ray bursts at the Baksan Underground Scintillation Telescope

The origin of gamma-ray bursts is still one of the unresolved problems in physics. They are short, intense, and non-repeating flashes of MeV gamma-rays with a wide range of spectral and temporal properties. Also these bursts are perhaps sources of neutrino emission. Unlike the photons, which may scatter or be absorbed, the neutrinos, due to their small interaction cross section, arrive at the Earth unaffected. This paper describes experimental methods for detection of low energy neutrinos in the range from 20 MeV to 100MeV at the Baksan Underground Scintillation Telescope. In the analysis we search neutrinos in time coincidence with a gamma-ray burst. We use filtered data collected at the Telescope during 2012. We also use the catalogue of gamma-ray bursts of the SWIFT satellite experiment.

GAMMA-RAY BURST FLARES: X-RAY FLARING. II.

We present a catalog of 497 flaring periods found in gamma-ray burst (GRB) light curves taken from the online XRT GRB Catalogue. We analyzed 680 individual light curves using a flare detection method developed and used on our UV/optical GRB Flare Catalog. The method makes use of the Bayesian Information Criterion to analyze the residuals of fitted GRB light curves and statistically determines the optimal fit to the light curve residuals in attempt to identify any additional features. These features, which we classify as flares, are identified by iteratively adding additional `breaks' to the light curve. We find evidence of flaring in 310 of the analyzed light curves. For those light curves with flares, we find an average number of ~1.5 flares per GRB. As with the UV/optical, flaring in our sample is generally confined to the first 1000 s of the afterglow, but can be detected to beyond 10^5 s. Only ~50% of the detected flares follow the `classical' definition of \Delta t/t << 1, with many of the largest flares exhibiting \Delta t/t ~ 1 and some exceeding this value.