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X-ray Spectral Components Observed in the Afterglow of GRB 130925A

Bellm, Eric C. and Barrière, Nicolas M. and Bhalerao, Varun and Boggs, Steven E. and Cenko, S. Bradley and Christensen, Finn E. and Craig, William W. and Forster, Karl and Fryer, Chris L. and Hailey, Charles J. and Harrison, Fiona A. and Horesh, Assaf and Kouveliotou, Chryssa and Madsen, Kristin K. and Miller, Jon M. and Ofek, Eran O. and Perley, Daniel A. and Rana, Vikram R. and Reynolds, Stephen P. and Stern, Daniel and Tomsick, John A. and Zhang, William W. (2014) X-ray Spectral Components Observed in the Afterglow of GRB 130925A. Astrophysical Journal Letters, 784 (2). Art. No. L19. ISSN 2041-8205. doi:10.1088/2041-8205/784/2/L19.

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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 × 10^5 and 10^6 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 (10^8 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bellm, Eric C.0000-0001-8018-5348
Barrière, Nicolas M.0000-0001-9407-9490
Bhalerao, Varun0000-0002-6112-7609
Boggs, Steven E.0000-0001-9567-4224
Cenko, S. Bradley0000-0003-1673-970X
Christensen, Finn E.0000-0001-5679-1946
Forster, Karl0000-0001-5800-5531
Fryer, Chris L.0000-0003-2624-0056
Harrison, Fiona A.0000-0003-2992-8024
Horesh, Assaf0000-0002-5936-1156
Kouveliotou, Chryssa0000-0003-1443-593X
Madsen, Kristin K.0000-0003-1252-4891
Ofek, Eran O.0000-0002-6786-8774
Perley, Daniel A.0000-0001-8472-1996
Rana, Vikram R.0000-0003-1703-8796
Stern, Daniel0000-0003-2686-9241
Tomsick, John A.0000-0001-5506-9855
Zhang, William W.0000-0002-1426-9698
Alternate Title:X-ray Spectral Components in the Afterglow of GRB 130925A
Additional Information:© American Astronomical Society. Received 2014 January 17; accepted 2014 February 26; published 2014 March 11. This work was supported under NASA contract No. NNG08FD60C and uses data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations team for executing the target of opportunity observations. This research has used the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). These results are based in part on observations made by the Chandra X-ray Observatory. We thank the Chandra director for granting discretionary time and the Chandra team for prompt execution of the observations. Facilities: NuSTAR, Swift, Chandra.
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Subject Keywords:gamma-ray burst: individual (GRB 130925A)
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2014-65
Issue or Number:2
Record Number:CaltechAUTHORS:20140520-095049434
Persistent URL:
Official Citation:X-Ray Spectral Components Observed in the Afterglow of GRB 130925A Eric C. Bellm et al. 2014 ApJ 784 L19
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45840
Deposited By: Ruth Sustaita
Deposited On:22 May 2014 17:38
Last Modified:10 Nov 2021 17:17

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