Giant X-Ray Bump in GRB 121027A: Evidence for Fall-back Disk Accretion
Abstract
A particularly interesting discovery in observations of GRB 121027A is that of a giant X-ray bump detected by the Swift/X-Ray Telescope. The X-ray afterglow re-brightens sharply at ~103 s after the trigger by more than two orders of magnitude in less than 200 s. This X-ray bump lasts for more than 104 s. It is quite different from typical X-ray flares. In this Letter we propose a fall-back accretion model to interpret this X-ray bump within the context of the collapse of a massive star for a long-duration gamma-ray burst. The required fall-back radius of ~3.5 × 1010 cm and mass of ~0.9-2.6 M ⊙ imply that a significant part of the helium envelope should survive through the mass loss during the last stage of the massive progenitor of GRB 121027A.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2013
- DOI:
- 10.1088/2041-8205/767/2/L36
- arXiv:
- arXiv:1302.4878
- Bibcode:
- 2013ApJ...767L..36W
- Keywords:
-
- accretion;
- accretion disks;
- black hole physics;
- gamma-ray burst: individual: GRB 121027A;
- magnetic fields;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, 3 figures, 2013, ApJL, 767:L36