Are the missing X-ray breaks in gamma-ray burst afterglow light curves merely hidden?
- 1Astronomical Institute, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands
- 2University of Alabama, National Space Science and Technology Centre, 320 Sparkman Drive, Huntsville, AL 35805, USA
- ↵*E-mail: pcurran{at}science.uva.nl
- In original form 2007 October 26.
- Received 2008 January 14.
- Accepted 2008 January 29.
- First published online May 11, 2008.
Abstract
Gamma-ray burst (GRB) afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared to the BeppoSAX or pre-Swift era. Specifically, relatively few breaks, consistent with jet breaks, are observed in the X-ray light curves of these bursts. If these breaks are truly missing, it has serious consequences on the interpretation of GRB jet collimation and energy requirements, and the use of GRBs as cosmological tools. Here, we address the issue of X-ray breaks that are possibly ‘hidden’ and hence the light curves are misinterpreted as being single power laws. We do so by synthesizing X-ray telescope (XRT) light curves and fitting both single and broken power laws, and comparing the relative goodness of each fit via Monte Carlo analysis. Even with the well-sampled light curves of the Swift era, these breaks may be left misidentified, hence caution is required when making definite statements on the absence of achromatic breaks.
Key words
- radiation mechanisms: non-thermal
- methods: analytical
- methods: statistical
- gamma rays: bursts
- X-rays: bursts
- © 2008 The Authors. Journal compilation © 2008 RAS
