THE BATSE 5B GAMMA-RAY BURST SPECTRAL CATALOG Goldstein, Adam; Preece, Robert D; Mallozzi, Robert S ...
The Astrophysical journal. Supplement series,
10/2013, Volume:
208, Issue:
2
Journal Article
Peer reviewed
We present systematic spectral analyses of gamma-ray bursts (GRBs) detected with the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory during its entire nine ...years of operation. This catalog contains two types of spectra extracted from 2145 GRBs, and fitted with five different spectral models resulting in a compendium of over 19,000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was devised to be as thorough and objective as possible. We describe in detail our procedures and criteria for the analyses, and present the bulk results in the form of parameter distributions. This catalog should be considered an official product from the BATSE Science Team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).
We present our results of the temporal and spectral analysis of a sample of 52 bright and hard gamma-ray bursts (GRBs) observed with the Fermi Gamma-ray Burst Monitor (GBM) during its first year of ...operation (2008 July-2009 July).Our sample was selected from a total of 253 GBM GRBs based on the event peak count rate measured between 0.2 and 40 MeV. The final sample comprised of 34 long and 18 short GRBs. These numbers show that the GBM sample contains a much larger fraction of short GRBs than the CGRO/BATSE data set, which we explain as the result of our (different) selection criteria, which favor collection of short, bright GRBs over BATSE. A first by-product of our selection methodology is the determination of a detection threshold from the GBM data alone, above which GRBs most likely will be detected in the MeV/GeV range with the Large Area Telescope on board Fermi. This predictor will be very useful for future multi-wavelength GRB follow-ups with ground- and space-based observatories. Further, we have estimated the burst durations up to 10 MeV and for the first time expanded the duration-energy relationship in the GRB light curves to high energies. We confirm that GRB durations decline with energy as a power law with index approximately --0.4, as was found earlier with the BATSE data and we also notice evidence of a possible cutoff or break at higher energies. Finally, we performed time-integrated spectral analysis of all 52 bursts and compared their spectral parameters with those obtained with the larger data sample of the BATSE data. We find that the two parameter data sets are similar and confirm that short GRBs are in general harder than longer ones.
CXCL10 is a chemokine for activated and memory T cells with many important immunological functions. We recently found that CXCL10 is upregulated in human muscle following contraction‐induced damage. ...No information is available on the role of CXCL10 in the context of muscle damage or repair. In this study, we confirm that CXCL10 is elevated in human muscle at 2 and 3 days following damage and perform cell culture and animal studies to examine the role of CXCL10 in muscle repair. CXCL10 did not impact proliferation rates of human primary myoblasts but it did promote myogenic differentiation in vitro, suggesting a possible direct impact on muscle regeneration. To test if CXCL10 was dispensable for effective muscle regeneration in vivo, we measured functional and histological markers of muscle repair out to 14 days postmuscle injury caused by a myotoxin in wild‐type (WT) mice and CXCL10 knockout (KO) mice. Between genotypes, no significant differences were found in loss or restoration of in situ muscle force, cross‐sectional area of newly formed myofibers, or the number of embryonic myosin heavy chain‐positive myofibers. In addition, KO animals were not deficient in T‐cell accumulation in the damaged muscle following injury. Gene expression of the other two ligands (CXCL9 and 11) that bind to the same receptor as CXCL10 were also elevated in the damaged muscle of KO mice. Thus, other ligands may have compensated for the lack of CXCL10 in the KO mice. We conclude that CXCL10 is not necessary for effective muscle regeneration.
This study was the first to investigate the role of the chemokine CXCL10 (also known as IP‐10) muscle regeneration following acute injury. CXCL10 was elevated in human muscle following contraction‐induced damage. However, CXCL10 knockout mice did not display any differences in muscle regeneration, restoration of functional capacity, or muscle T‐cell accumulation compared to the wild‐type animals.
The Swift/Burst Alert Telescope detected the first burst from 1E 1841--045 in 2010 May with intermittent burst activity recorded through at least 2011 July. Here we present Swift and Fermi/Gamma-ray ...Burst Monitor observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T 90 durations of the bursts range between 18 and 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) X 1038 erg, which is on the low side of soft gamma repeater bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in 1E 1841--045 might not involve large-scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.
We demonstrate that distinguishable gamma-ray burst (GRB) pulses exhibit similar behaviors as evidenced by correlations among the observable pulse properties of duration, peak luminosity, fluence, ...spectral hardness, energy-dependent lag, and asymmetry. Long and Short burst pulses exhibit these behaviors, suggesting that a similar process is responsible for producing all GRB pulses. That these properties correlate in the observer's frame indicates that intrinsic correlations are strong enough to not be diluted into insignificance by the dispersion in distances and redshift. We show how all correlated pulse characteristics can be explained by hard-to-soft pulse evolution, and we demonstrate that 'intensity tracking' pulses not having these properties are not single pulses; they instead appear to be composed of two or more overlapping hard-to-soft pulses. In order to better understand pulse characteristics, we recognize that hard-to-soft evolution provides a more accurate definition of a pulse than its intensity variation. This realization, coupled with the observation that pulses begin near-simultaneously across a wide range of energies, leads us to conclude that the observed pulse emission represents the energy decay resulting from an initial injection, and that one simple and as yet unspecified physical mechanism is likely to be responsible for all GRB pulses regardless of the environment in which they form and, if GRBs originate from different progenitors, then of the progenitors that supply them with energy.
A number of recent theory and simulation results by Nordlund, Hededal, Nishikawa, Medvedev, Brainerd and others are improving our understanding of the prompt emission of GRBs. Observations of GBM ...spectra from various instruments have consistently painted a picture that tends not to support the prevailing hydrodynamic synchrotron shock models. I will attempt to put the observations and the recent results together into a coherent picture that suggests new directions for future investigations by theory, simulations as well as observations, especially by GLAST.
The Spectral Sharpness Angle of Gamma-ray Bursts Yu, Hoi-Fung; van Eerten, Hendrik J.; Greiner, Jochen ...
Journal of astronomy and space sciences,
06/2016, Volume:
33, Issue:
2
Journal Article
Peer reviewed
Open access
We extend the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to ...the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58+23 -18% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase.
Aims. We aim to obtain high-quality time-resolved spectral fits of gamma-ray bursts observed by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Methods. We performed ...time-resolved spectral analysis with high temporal and spectral resolution of the brightest bursts observed by Fermi GBM in its first four years of mission. Results. We present the complete catalog containing 1491 spectra from 81 bursts with high spectral and temporal resolution. Distributions of parameters, statistics of the parameter populations, parameter-parameter and parameter-uncertainty correlations, and their exact values are obtained and presented as main results in this catalog. We report a criterion that is robust enough to automatically distinguish between different spectral evolutionary trends between bursts. We also search for plausible blackbody emission components and find that only three bursts (36 spectra in total) show evidence of a pure Planck function. It is observed that peak energy and the averaged, time-resolved power-law index at low energy are slightly harder than the time-integrated values. Time-resolved spectroscopic results should be used instead of time-integrated results when interpreting physics from the observed spectra.
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