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

Creators: Bellm, Eric C.; Barrière, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Reynolds, Stephen P.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

Abstract

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.

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.

Attached Files

Published - 2041-8205_784_2_L19.pdf

Submitted - 1402.6755v1.pdf

Files

1402.6755v1.pdf

Files (2.1 MB)

Name	Size	Download all
1402.6755v1.pdf md5:451d77ed774573573287844a6c8fcc1e	886.0 kB	Preview Download
2041-8205_784_2_L19.pdf md5:3f0519ce8fc9294f60be4c0f652564d8	1.2 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes