- ID:
- ivo://CDS.VizieR/J/ApJ/702/489
- Title:
- ROTSE observations of gamma-ray burst afterglows
- Short Name:
- J/ApJ/702/489
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a complete set of early optical afterglows of gamma-ray bursts (GRBs) obtained with the Robotic Optical Transient Search Experiment (ROTSE-III) telescope network from 2005 March through 2007 June. This set is comprised of 12 afterglows with early optical and Swift/X-Ray Telescope observations, with a median ROTSE-III response time of 45s after the start of {gamma}-ray emission (8s after the GCN notice time). These afterglows span 4 orders of magnitude in optical luminosity, and the contemporaneous X-ray detections allow multi-wavelength spectral analysis. Excluding X-ray flares, the broadband synchrotron spectra show that the optical and X-ray emission originate in a common region, consistent with predictions of the external forward shock in the fireball model. However, the fireball model is inadequate to predict the temporal decay indices of the early afterglows, even after accounting for possible long-duration continuous energy injection. We find that the optical afterglow is a clean tracer of the forward shock, and we use the peak time of the forward shock to estimate the initial bulk Lorentz factor of the GRB outflow, and find 100<~{Gamma}_0_<~1000, consistent with expectations.
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- ID:
- ivo://CDS.VizieR/J/A+A/612/A6
- Title:
- RX J1713.7-3946 HESS spectrum
- Short Name:
- J/A+A/612/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Supernova remnants exhibit shock fronts (shells) that can accelerate charged particles up to very high energies. In the past decade, measurements of a handful of shell-type supernova remnants in very high-energy gamma rays have provided unique insights into the acceleration process. Among those objects, RX J1713.7-3946 (also known as G347.3-0.5) has the largest surface brightness, allowing us in the past to perform the most comprehensive study of morphology and spatially resolved spectra of any such very high-energy gamma-ray source. Here we present extensive new H.E.S.S. measurements of RX J1713.7-3946, almost doubling the observation time compared to our previous publication. Combined with new improved analysis tools, the previous sensitivity is more than doubled. The H.E.S.S. angular resolution of 0.048{deg} (0.036{deg} above 2TeV) is unprecedented in gamma-ray astronomy and probes physical scales of 0.8 (0.6) parsec at the remnant's location. The new H.E.S.S. image of RX J1713.7-3946 allows us to reveal clear morphological differences between X-rays and gamma rays. In particular, for the outer edge of the brightest shell region, we find the first ever indication for particles in the process of leaving the acceleration shock region. By studying the broadband energy spectrum, we furthermore extract properties of the parent particle populations, providing new input to the discussion of the leptonic or hadronic nature of the gamma-ray emission mechanism.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/75
- Title:
- Search for GW signals associated with GRBs
- Short Name:
- J/ApJ/886/75
- Date:
- 02 Feb 2022 13:41:32
- Publisher:
- CDS
- Description:
- We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of <9.38x10^-6^ (modeled) and 3.1x10^-4^ (unmodeled). We do not find any significant evidence for gravitational-wave signals associated with the other gamma-ray bursts analyzed, and therefore we report lower bounds on the distance to each of these, assuming various source types and signal morphologies. Using our final modeled search results, short gamma-ray burst observations, and assuming binary neutron star progenitors, we place bounds on the rate of short gamma-ray bursts as a function of redshift for z<=1. We estimate 0.07-1.80 joint detections with Fermi-GBM per year for the 2019-20 LIGO-Virgo observing run and 0.15-3.90 per year when current gravitational-wave detectors are operating at their design sensitivities.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A13
- Title:
- Second AGILE catalogue of gamma-ray sources
- Short Name:
- J/A+A/627/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second AGILE-GRID catalogue (2AGL) of gamma-ray sources in the energy range 100MeV-10GeV. With respect to previous AGILE-GRID catalogues, the current 2AGL catalogue is based on the first 2.3 years of science data from the AGILE mission (the so-called pointing mode) and incorporates more data and several analysis improvements, including better calibrations at the event reconstruction level, an updated model for the Galactic diffuse gamma-ray emission, a refined procedure for point-like source detection, and the inclusion of a search for extended gamma-ray sources. The 2AGL catalogue includes 175 high-confidence sources (above 4{sigma} significance) with their location regions and spectral properties and a variability analysis with four-day light curves for the most significant. Relying on the error region of each source position, including systematic uncertainties, 122 sources are considered as positionally associated with known counterparts at different wavelengths or detected by other gamma-ray instruments. Among the identified or associated sources, 62 are active galactic nuclei (AGNs) of the blazar class. Pulsars represent the largest Galactic source class, with 41 associated pulsars, 7 of which have detected pulsation; 8 supernova remnants and 4 high-mass X-ray binaries have also been identified. A substantial number of 2AGL sources are unidentified: for 53 sources no known counterpart is found at different wavelengths. Among these sources, we discuss a subclass of 29 AGILE-GRID-only gamma-ray sources that are not present in 1FGL, 2FGL, or 3FGL catalogues; the remaining sources are unidentified in both 2AGL and 3FGL catalogues. We also present an extension of the analysis of 2AGL sources detected in the energy range 50-100MeV.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/765
- Title:
- Second IBIS/ISGRI soft gamma-ray survey catalog
- Short Name:
- J/ApJ/636/765
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we report the second soft gamma-ray source catalog obtained with the IBIS/ISGRI gamma-ray imager on board the INTEGRAL satellite. The scientific data set is based on more than 10Ms of high-quality observations performed during the first 2 years of Core Program and public IBIS/ISGRI observations, and covers 50% of the whole sky. The main aim of the first survey was to scan systematically, for the first time at energies above 20keV, the whole Galactic plane to achieve a limiting sensitivity of 1mCrab in the central radian. The target of the second year of the INTEGRAL mission lifetime was to expand as much as possible our knowledge of the soft gamma-ray sky, with the same limiting sensitivity, to at least 50% of the whole sky, mainly by including a substantial coverage of extragalactic fields. This catalog comprises more than 200 high-energy sources detected in the energy range 20-100keV, including new transients not active during the first year of operation, faint persistent objects revealed with longer exposure time, and several Galactic and extragalactic sources in sky regions not observed in the first survey. The mean position error for all the sources detected with significance above 10{sigma} is 40", enough to identify most of them with a known X-ray counterpart and to unveil the nature of most of the strongly absorbed ones, even though they are very difficult to detect in X-rays.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/1407
- Title:
- SED of the Fermi blazars
- Short Name:
- J/ApJ/709/1407
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We complied the optical, X-ray, and {gamma}-ray data for 54 Fermi blazars and studied the relationship between the broadband spectral index {alpha}_ox_ and {alpha}_x{gamma}_, as well as the relationship between the intrinsic composite spectral indices {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ for this sample. The relationship between {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ reveals that flat spectrum radio quasars and low-energy peaked BL Lacertae follow a continuous trend, which is consistent with previous results, whereas high-energy peaked BL Lacertae follow a separate distinct trend. Even so, a unified scheme is also revealed from {alpha}_xox_-{alpha}_{gamma}x{gamma}_ diagram when all three subclasses of blazars are considered.
- ID:
- ivo://CDS.VizieR/J/ApJ/744/141
- Title:
- Shapes of GRB light curves
- Short Name:
- J/ApJ/744/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The light curves of gamma-ray bursts (GRBs) are believed to result from internal shocks reflecting the activity of the GRB central engine. Their temporal deconvolution can reveal potential differences in the properties of the central engines in the two populations of GRBs which are believed to originate from the deaths of massive stars (long) and from mergers of compact objects (short). We present here the results of the temporal analysis of 42 GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope. We deconvolved the profiles into pulses, which we fit with lognormal functions. The distributions of the pulse shape parameters and intervals between neighboring pulses are distinct for both burst types and also fit with lognormal functions. We have studied the evolution of these parameters in different energy bands and found that they differ between long and short bursts. We discuss the implications of the differences in the temporal properties of long and short bursts within the framework of the internal shock model for GRB prompt emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/1
- Title:
- Short gamma-ray bursts (sGRBs) data
- Short Name:
- J/ApJ/852/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we study the luminosity function and formation rate of short gamma-ray bursts (sGRBs). First, we derive the Ep-Lp correlation using 16 sGRBs with redshift measurements and determine the pseudo redshifts of 284 Fermi sGRBs. Then, we use the Lynden-Bell c^-^ method to study the luminosity function and formation rate of sGRBs without any assumptions. A strong evolution of luminosity L(z){propto}(1+z)^4.47^ is found. After removing this evolution, the luminosity function is {Psi}(L){propto}L_0_^-0.29+/-0.01^ for dim sGRBs and {psi}(L){propto}L_0_^-1.07+/-0.01^ for bright sGRBs, with the break point 8.26x10^50^erg/s. We also find that the formation rate decreases rapidly at z<1.0, which is different from previous works. The local formation rate of sGRBs is 7.53 events Gpc^-3^/yr. Considering the beaming effect, the local formation rate of sGRBs including off-axis sGRBs is 203.31_-135.54_^+1152.09^ events Gpc^-3^/yr. We also estimate that the event rate of sGRBs detected by the advanced LIGO and Virgo is 0.85_-0.56_^+4.82^ events yr^-1^ for an NS-NS binary.
- ID:
- ivo://CDS.VizieR/J/ApJ/687/1201
- Title:
- SN and LGRB locations in their host galaxies
- Short Name:
- J/ApJ/687/1201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- When the afterglow fades at the site of a long-duration {gamma}-ray burst (LGRB), Type Ic supernovae (SNe Ic) are the only type of core-collapse supernova observed. Here we examine 504 supernovae with types assigned based on their spectra that are located in nearby (z<0.06) galaxies for which we have constructed surface photometry from the Sloan Digital Sky Survey (SDSS). The distributions of the thermonuclear supernovae (SNe Ia) and some varieties of core-collapse supernovae (SNe II and SNe Ib) follow the galaxy light, but the SNe Ic (like LGRBs) are much more likely to erupt in the brightest regions of their hosts.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A85
- Title:
- SN 1998bw MUSE datacube
- Short Name:
- J/A+A/602/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spatially resolved spectroscopy of the environments of explosive transients carries detailed information about the physical properties of the stellar population that gave rise to the explosion, and thus the progenitor itself. Here, we present new observations of ESO184-G82, the galaxy hosting the archetype of the {gamma}-ray burst/supernova connection, GRB 980425/SN 1998bw, obtained with the integral field spectrograph MUSE mounted at the Very Large Telescope. These observations have yielded detailed maps of emission-line strength for various nebular lines along with physical parameters such as dust extinction, stellar age, and oxygen abundance on spatial scales of 160pc. The immediate environment of GRB 980425 is young 5-8Myr) and consistent with a mildly extinguished (AV~0.1mag) progenitor of zero-age main-sequence mass between 25 M_{sun}_ and 40 M_{sun}_ and an oxygen abundance 12+log(O=H)~8.2 (Z~0.3Z_{sun}_), which is slightly lower than that of an integrated measurement of the whole galaxy (12+log(O=H)~8.3) and a prominent nearby HII region (12+log(O/H)~8.4). This region is significantly younger than the explosion site, and we argue that a scenario in which the GRB progenitor formed in this environment and was subsequently ejected appears very unlikely. We show that empirical strong-line methods based on [O iii] and/or [N ii] are inadequate to produce accurate maps of oxygen abundance at the level of detail of our MUSE observation as these methods strongly depend on the ionization state of the gas. The metallicity gradient in ESO184-G82 is -0.06dex/kpc, indicating that the typical offsets of at most few kpc for cosmological GRBs on average have a small impact on oxygen abundance measurements at higher redshift.
