skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Opportunities for GRB Discovery Combining Swift and GLAST

Abstract

Swift is a NASA MIDEX mission with primary objective to study GRBs and use them to study the Universe. The mission was launched on 20 November 2004 and is detecting {approx}100 gamma-ray bursts (GRBs) each year. .For almost every burst there is a prompt (within {approx}90 s) spacecraft repointing to give X-ray and UV/optical observations of the afterglow. Swift has already collected an impressive database including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows, and rapid follow-up by other observatories notified through the GCN. With the launch of GLAST in 2007, there will be an opportunity to combine the powers of Swift and GLAST to make tremendous progress in the study of GRBs. This paper summarizes scientific results from Swift and discusses the ways that Swift and GLAST can work together on GRB observations.

Authors:
 [1];  [1];  [2]
  1. Code 661, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
21057314
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 906; Journal Issue: 1; Conference: Stockholm symposium on GRB's: Gamma-ray bursts prospects for GLAST, Stockholm (Sweden), 1 Sep 2006; Other Information: DOI: 10.1063/1.2737414; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; AFTERGLOW; COSMIC GAMMA BURSTS; COSMIC PHOTONS; GAMMA ASTRONOMY; GAMMA RADIATION; NASA; PHOTON EMISSION; RADIATION MONITORING; SENSITIVITY; TELESCOPE COUNTERS; UNIVERSE; X RADIATION

Citation Formats

Gehrels, Neil, Cannizzo, John K., and Joint Center for Astrophysics, University of Maryland, Baltimore County, Baltimore, MD 21250. Opportunities for GRB Discovery Combining Swift and GLAST. United States: N. p., 2007. Web. doi:10.1063/1.2737414.
Gehrels, Neil, Cannizzo, John K., & Joint Center for Astrophysics, University of Maryland, Baltimore County, Baltimore, MD 21250. Opportunities for GRB Discovery Combining Swift and GLAST. United States. doi:10.1063/1.2737414.
Gehrels, Neil, Cannizzo, John K., and Joint Center for Astrophysics, University of Maryland, Baltimore County, Baltimore, MD 21250. Tue . "Opportunities for GRB Discovery Combining Swift and GLAST". United States. doi:10.1063/1.2737414.
@article{osti_21057314,
title = {Opportunities for GRB Discovery Combining Swift and GLAST},
author = {Gehrels, Neil and Cannizzo, John K. and Joint Center for Astrophysics, University of Maryland, Baltimore County, Baltimore, MD 21250},
abstractNote = {Swift is a NASA MIDEX mission with primary objective to study GRBs and use them to study the Universe. The mission was launched on 20 November 2004 and is detecting {approx}100 gamma-ray bursts (GRBs) each year. .For almost every burst there is a prompt (within {approx}90 s) spacecraft repointing to give X-ray and UV/optical observations of the afterglow. Swift has already collected an impressive database including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows, and rapid follow-up by other observatories notified through the GCN. With the launch of GLAST in 2007, there will be an opportunity to combine the powers of Swift and GLAST to make tremendous progress in the study of GRBs. This paper summarizes scientific results from Swift and discusses the ways that Swift and GLAST can work together on GRB observations.},
doi = {10.1063/1.2737414},
journal = {AIP Conference Proceedings},
number = 1,
volume = 906,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • Recent observations of early X-ray afterglows of GRBs by the Swift satellite - prior to t {approx} 103s but well after the end of the burst - show most GRBs to be followed by highly time and energy variable emission. This was unexpected prior to Swift and physical mechanisms remain largely mysterious. The spectra exhibit a strong hard-to-soft evolution which tracks the flux, consistent with a well-established hardness intensity correlation for the prompt Gamma-ray emission. The light curves show dramatic flares or rapid logarithmic time decays. In the simplest interpretation, this emission is GRB-like and indicates a long lived energymore » source with the possibility of interacting shells of widely varying bulk Lorentz factor. We review the phenomenology in order to ascertain how GLAST observations of this early emission, either detected directly or through the detection of inverse-Compton emission, can help to rule on possible models.« less
  • A golden age of GRB astronomy will be upon us when GLAST launches in late 2007 and Swift continues its mission. The Swift NASA MIDEX launched in November 2004 and is detecting {approx}100 gamma-ray bursts (GRBs) each year. For almost every burst there is a prompt (within {approx}90 s) spacecraft repointing to give X-ray and UV/optical observations of the afterglow. Swift has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows, and rapid follow-up by other observatories notified through the GCN. With the launch of GLAST, there will be the opportunity tomore » combine the powers of Swift and GLAST to make tremendous progress in the study of GRBs. GRBs detected by either mission will trigger observation by the other to give multiwavelength data on prompt and afterglow emission from optical through GeV gamma rays. This paper summarizes scientific results from Swift and CGRO/EGRET and discusses the ways that Swift and GLAST can work together on GRB observations.« less
  • We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to 2009 September, for a total of 76 GRBs, and present an additional three pre-Swift GRBs not included in an earlier sample. Furthermore, we publish 840 additional new photometry data points on a total of 42 GRB afterglows, including large data sets for GRBs 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A, and 080810. We analyzed the light curves of all GRBs in the sample and derived spectral energy distributions for the sample with the best data quality, allowingmore » us to estimate the host-galaxy extinction. We transformed the afterglow light curves into an extinction-corrected z = 1 system and compared their luminosities with a sample of pre-Swift afterglows. The results of a former study, which showed that GRB afterglows clustered and exhibited a bimodal distribution in luminosity space, are weakened by the larger sample. We found that the luminosity distribution of the two afterglow samples (Swift-era and pre-Swift) is very similar, and that a subsample for which we were not able to estimate the extinction, which is fainter than the main sample, can be explained by assuming a moderate amount of line-of-sight host extinction. We derived bolometric isotropic energies for all GRBs in our sample, and found only a tentative correlation between the prompt energy release and the optical afterglow luminosity at 1 day after the GRB in the z = 1 system. A comparative study of the optical luminosities of GRB afterglows with echelle spectra (which show a high number of foreground absorbing systems) and those without, reveals no indication that the former are statistically significantly more luminous. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Most GRBs feature afterglows that are dominated by the forward shock from early times on. Finally, we present the first indications of a class of long GRBs, which form a bridge between the typical high-luminosity, high-redshift events and nearby low-luminosity events (which are also associated with spectroscopic supernovae) in terms of energetics and observed redshift distribution, indicating a continuous distribution overall.« less
  • Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called 'short/hard' and 'long/soft'. The latter have been conclusively linked to the explosive deaths of massive stars, while the former are thought to result from the merger or collapse of compact objects. In recent years, indications have been accumulating that the short/hard versus long/soft division does not map directly onto what would be expected from the two classes of progenitors, leading to a new classification scheme called Type I and Type II which is based on multiple observational criteria. We use amore » large sample of GRB afterglow and prompt-emission data (adding further GRB afterglow observations in this work) to compare the optical afterglows (or the lack thereof) of Type I GRBs with those of Type II GRBs. In comparison to the afterglows of Type II GRBs, we find that those of Type I GRBs have a lower average luminosity and show an intrinsic spread of luminosities at least as wide. From late and deep upper limits on the optical transients, we establish limits on the maximum optical luminosity of any associated supernova (SN), confirming older works and adding new results. We use deep upper limits on Type I GRB optical afterglows to constrain the parameter space of possible mini-SN emission associated with a compact-object merger. Using the prompt-emission data, we search for correlations between the parameters of the prompt emission and the late optical afterglow luminosities. We find tentative correlations between the bolometric isotropic energy release and the optical afterglow luminosity at a fixed time after the trigger (positive), and between the host offset and the luminosity (negative), but no significant correlation between the isotropic energy release and the duration of the GRBs. We also discuss three anomalous GRBs, GRB 060505, GRB 060614, and GRB 060121, in light of their optical afterglow luminosities.« less
  • The Gamma-ray Large Area Space Telescope (GLAST) will observe the gamma-ray sky in the MeV and GeV energy range. It will detect a number of gamma-ray bursts (GRBs) every year, depending on their emission at high energies, which is still unknown. GLAST will be the first instrument observing GRBs at energies above 20 GeV. A systematic study prior to launch, which is foreseen for 15 November 2007, was the GLAST Data Challenge 2 (DC 2). For GLAST DC 2 two month of data taking were simulated. Based on these simulations the GRB Working Group performed systematic studies of the performancemore » of GLAST in observing GRBs. These studies included the spectral analysis of the prompt emission, a position fit of the GRB, and the search for prompt and afterglow emissions in the LAT data.« less