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Title: X-RAY SPECTRAL COMPONENTS OBSERVED IN THE AFTERGLOW OF GRB 130925A

We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between two observation epochs at 2 × 10{sup 5} and 10{sup 6} s after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several keV width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10{sup 8} cm), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.
Authors:
; ; ; ; ;  [1] ; ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ; ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] more »; « less
  1. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
  3. Inter-University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India)
  4. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  5. DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
  6. CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
  7. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
  8. Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel)
  9. Astrophysics Office/ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)
  10. Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  11. Physics Department, NC State University, Raleigh, NC 27695 (United States)
  12. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
Publication Date:
OSTI Identifier:
22365949
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 784; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; AFTERGLOW; COSMIC GAMMA BURSTS; COSMIC PHOTONS; COSMIC X-RAY SOURCES; KEV RANGE; TELESCOPES; X RADIATION; X-RAY DETECTION