- ID:
- ivo://CDS.VizieR/J/ApJ/860/L21
- Title:
- GROND, NOT & VLT/X-shooter obs. of GRB180325A
- Short Name:
- J/ApJ/860/L21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ultraviolet (UV) extinction feature at 2175{AA} is ubiquitously observed in the Galaxy but is rarely detected at high redshifts. Here we report the spectroscopic detection of the 2175{AA} bump on the sightline to the {gamma}-ray burst (GRB) afterglow GRB180325A at z=2.2486, the only unambiguous detection over the past 10 years of GRB follow-up, at four different epochs with the Nordic Optical Telescope (NOT) and the Very Large Telescope (VLT)/X-shooter. Additional photometric observations of the afterglow are obtained with the Gamma-Ray burst Optical and Near-Infrared Detector (GROND). We construct the near-infrared to X-ray spectral energy distributions (SEDs) at four spectroscopic epochs. The SEDs are well described by a single power law and an extinction law with RV~4.4, Av~1.5, and the 2175{AA} extinction feature. The bump strength and extinction curve are shallower than the average Galactic extinction curve. We determine a metallicity of [Zn/H]{>}-0.98 from the VLT/X-shooter spectrum. We detect strong neutral carbon associated with the GRB with equivalent width of Wr({lambda}1656)=0.85+/-0.05. We also detect optical emission lines from the host galaxy. Based on the H{alpha} emission-line flux, the derived dust-corrected star formation rate is ~46+/-4M_{sun}_/yr and the predicted stellar mass is log M*/M_{sun}_~9.3+/-0.4, suggesting that the host galaxy is among the main-sequence star-forming galaxies.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/478/2
- Title:
- IR-bright gamma-ray burst host galaxies
- Short Name:
- J/MNRAS/478/2
- Date:
- 17 Jan 2022 00:28:54
- Publisher:
- CDS
- Description:
- We identify and explore the properties of an infrared-bright gamma-ray burst (GRB) host population. Candidate hosts are selected by coincidence with sources in WISE, with matching to random coordinates and a false alarm probability analysis showing that the contamination fraction is ~0.5. This methodology has already identified the host galaxy of GRB 080517. We combine survey photometry from Pan-STARRS, SDSS, APASS, 2MASS, GALEX, and WISE with our own WHT/ACAM and VLT/X-shooter observations to classify the candidates and identify interlopers. Galaxy SED fitting is performed using MAGPHYS, in addition to stellar template fitting, yielding 13 possible IR-bright hosts. A further seven candidates are identified from the previously published work. We report a candidate host for GRB 061002, previously unidentified as such. The remainder of the galaxies have already been noted as potential hosts. Comparing the IR-bright population properties including redshift z, stellar mass M*, star formation rate SFR, and V-band attenuation A_V_ to GRB host catalogues in the literature, we find that the infrared-bright population is biased towards low z, high M*, and high A_V_. This naturally arises from their initial selection - local and dusty galaxies are more likely to have the required IR flux to be detected in WISE. We conclude that while IR-bright GRB hosts are not a physically distinct class, they are useful for constraining existing GRB host populations, particularly for long GRBs.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/161
- Title:
- Konus-Wind cat. of GRBs with redshifts. I.
- Short Name:
- J/ApJ/850/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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 0.1<=z<=5, 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 z~16.6, 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/159
- Title:
- Late X-ray emission of binary-driven hypernovae
- Short Name:
- J/ApJ/833/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has previously been discovered that there is a universal power-law behavior exhibited by the late X-ray emission (LXRE) of a "golden sample" of six long energetic GRBs, when observed in the rest frame of the source. This remarkable feature, independent of the different isotropic energy (E_iso_) of each GRB, has been used to estimate the cosmological redshift of some long GRBs. This analysis is extended here to a new class of 161 long GRBs, all with E_iso_>10^52^erg. These GRBs are indicated as binary-driven hypernovae (BdHNe) in view of their progenitors: a tight binary system composed of a carbon-oxygen core (CO_core_) and a neutron star undergoing an induced gravitational collapse (IGC) to a black hole triggered by the CO_core_ explosion as a supernova (SN).
- ID:
- ivo://CDS.VizieR/J/ApJ/903/33
- Title:
- 1366 LGRB redshifts estimates with BARSE
- Short Name:
- J/ApJ/903/33
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We present a catalog of probabilistic redshift estimates for 1366 individual Long-duration Gamma-ray Bursts (LGRBs) detected by the Burst And Transient Source Experiment (BATSE). This result is based on a careful selection and modeling of the population distribution of 1366 BATSE LGRBs in the five-dimensional space of redshift and the four intrinsic prompt gamma-ray emission properties: the isotropic 1024ms peak luminosity (L_iso_), the total isotropic emission (E_iso_), the spectral peak energy (E_pz_), as well as the intrinsic duration (T_90z_), while carefully taking into account the effects of sample incompleteness and the LGRB-detection mechanism of BATSE. Two fundamental plausible assumptions underlie our purely probabilistic approach: (1) LGRBs trace, either exactly or closely, the cosmic star formation rate, with a possibility of the excess rates of LGRBs in the nearby universe, and (2) the joint four-dimensional distribution of the aforementioned prompt gamma-ray emission properties is well described by a multivariate log-normal distribution. Our modeling approach enables us to constrain the redshifts of individual BATSE LGRBs to within 0.36 and 0.96 average uncertainty ranges at 50% and 90% confidence levels, respectively. Our redshift predictions are completely at odds with the previous redshift estimates of BATSE LGRBs that were computed via the proposed phenomenological high-energy relations, specifically, the apparently strong correlation of LGRBs' peak luminosity with the spectral peak energy, lightcurve variability, and spectral lag. The observed discrepancies between our predictions and the previous works can be explained by the strong influence of detector threshold and sample incompleteness in shaping these phenomenologically proposed high-energy correlations in the literature. Finally, we also discuss the potential effects of an excess cosmic rate of LGRBs at low redshifts and the possibility of a luminosity evolution of LGRBs on our results.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/94
- Title:
- Multiwavelength obs. of GRB 161219B
- Short Name:
- J/ApJ/862/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present detailed multiwavelength observations of GRB 161219B at z=0.1475, spanning the radio to X-ray regimes, and the first Atacama Large Millimeter/submillimeter Array (ALMA) light curve of a {gamma}-ray burst (GRB) afterglow. The centimeter- and millimeter-band observations before 8.5 days require emission in excess of that produced by the afterglow forward shock (FS). These data are consistent with radiation from a refreshed reverse shock (RS) produced by the injection of energy into the FS, signatures of which are also present in the X-ray and optical light curves. We infer a constant- density circumburst environment with an extremely low density, n_0_~3x10^-4^cm^-3^, and show that this is a characteristic of all strong RS detections to date. The Karl G. Lansky Very Large Array (VLA) observations exhibit unexpected rapid variability on roughly minute timescales, indicative of strong interstellar scintillation. The X-ray, ALMA, and VLA observations together constrain the jet break time, t_jet_~32 days, yielding a wide jet opening angle of {theta}_jet_~13{deg}, implying beaming-corrected {gamma}-ray and kinetic energies of E_{gamma}~4.9x10^48^erg and E_K_~1.3x10^50^erg, respectively. Comparing the RS and FS emission, we show that the ejecta are only weakly magnetized, with relative magnetization, R_B_~1, compared to the FS. These direct, multifrequency measurements of a refreshed RS spanning the optical to radio bands highlight the impact of radio and millimeter data in probing the production and nature of GRB jets.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/126
- Title:
- New spectral lag measurements of 50 Fermi/GBM GRBs
- Short Name:
- J/ApJ/844/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We carry out a systematical study of the spectral lag properties of 50 single-pulsed gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor. By dividing the light curves into multiple consecutive energy channels, we provide a new measurement of the spectral lag that is independent of energy channel selections. We perform a detailed statistical study of our new measurements. We find two similar power-law energy dependencies of both the pulse arrival time and pulse width. Our new results on the power-law indices would favor the relativistic geometric effects for the origin of spectral lag. However, a complete theoretical framework that can fully account for the diverse energy dependencies of both arrival time and pulse width revealed in this work is still lacking. We also study the spectral evolution behaviors of the GRB pulses. We find that a GRB pulse with negligible spectral lag would usually have a shorter pulse duration and would appear to have a "hardness-intensity tracking" behavior, and a GRB pulse with a significant spectral lag would usually have a longer pulse duration and would appear to have a "hard-to-soft" behavior.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/118
- Title:
- Optical obs. of GRB 180205A with COATLI
- Short Name:
- J/ApJ/872/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical photometry of the afterglow of the long GRB 180205A with the COATLI telescope from 217s to about 5d after the Swift/BAT trigger. We analyze this photometry in conjunction with the X-ray light curve from Swift/XRT. The late-time light curves and spectra are consistent with the standard forward-shock scenario. However, the early-time optical and X-ray light curves show atypical behavior; the optical light curve exhibits a flat plateau while the X-ray light curve shows a flare. We explore several scenarios and conclude that the most likely explanation for the early behavior is late activity of the central engine.
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/1027
- Title:
- Photometry of the afterglow of GRB 130831A
- Short Name:
- J/MNRAS/455/1027
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, yet the nature and physical properties of their energy sources are far from understood. Very important clues, however, can be inferred by studying the afterglows of these events. We present optical and X-ray observations of GRB 130831A obtained by Swift, Chandra, Skynet, Reionization And Transients Infra-Red camera, Maidanak, International Scientific Optical-Observation Network, Nordic Optical Telescope, Liverpool Telescope and Gran Telescopio Canarias. This burst shows a steep drop in the X-ray light curve at ~10^5^ s after the trigger, with a power-law decay index of {alpha}~6. Such a rare behaviour cannot be explained by the standard forward shock (FS) model and indicates that the emission, up to the fast decay at 10^5^ s, must be of "internal origin", produced by a dissipation process within an ultrarelativistic outflow. We propose that the source of such an outflow, which must produce the X-ray flux for ~1 d in the cosmological rest frame, is a newly born magnetar or black hole. After the drop, the faint X-ray afterglow continues with a much shallower decay. The optical emission, on the other hand, shows no break across the X-ray steep decrease, and the late-time decays of both the X-ray and optical are consistent. Using both the X-ray and optical data, we show that the emission after ~10^5^ s can be explained well by the FS model. We model our data to derive the kinetic energy of the ejecta and thus measure the efficiency of the central engine of a GRB with emission of internal origin visible for a long time. Furthermore, we break down the energy budget of this GRB into the prompt emission, the late internal dissipation, the kinetic energy of the relativistic ejecta, and compare it with the energy of the associated supernova, SN 2013 fu.
- ID:
- ivo://CDS.VizieR/J/ApJ/843/143
- Title:
- Polarimetry & photometry of GRB with RINGO2
- Short Name:
- J/ApJ/843/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of early-time (~10^2^-10^4^s) photometry and polarimetry of all gamma-ray burst (GRB) optical afterglows observed with the RINGO2 imaging polarimeter on the Liverpool Telescope. Of the 19 optical afterglows observed, the following nine were bright enough to perform photometry and attempt polarimetry: GRB100805A, GRB101112A, GRB110205A, GRB110726A, GRB120119A, GRB120308A, GRB120311A, GRB120326A, and GRB120327A. We present multiwavelength light curves for these 9 GRBs, together with estimates of their optical polarization degrees and/or limits. We carry out a thorough investigation of detection probabilities, instrumental properties, and systematics. Using two independent methods, we confirm previous reports of significant polarization in GRB 110205A and 120308A, and report the new detection of P=6_-2_^+3^% in GRB101112A. We discuss the results for the sample in the context of the reverse- and forward-shock afterglow scenario, and show that GRBs with detectable optical polarization at early time have clearly identifiable signatures of reverse-shock emission in their optical light curves. This supports the idea that GRB ejecta contain large-scale magnetic fields, and it highlights the importance of rapid-response polarimetry.
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