Constraints on the source for gamma-ray bursts from observed X-ray afterglows
Abstract
It is widely known that the X-ray afterglows from long-duration gamma ray bursts (GRBs) are often associated with energetic Type Ic supernovae and that they approximately obey a universal scaling law. Here, we discuss a model for X-ray emission from accelerated relativistic electrons within an outgoing relativistic shock. We show that such a universal scaling imposes three constraints: 1) The shock energy is nearly the same for all bursts independently of when the shock arrives at the power-law regime, i.e. the energy in the outgoing shock (∼ 1051 ergs) is independent of the observed GRB luminosity; 2) In the power-law epoch, the shock propagates through an optically thin low-density (∼ 1 cm-3) medium; 3) The shock radiates adiabatically. These facts suggest that the late-time power-law afterglow emission derives from material in the associated supernova that is shocked by the GRB. We argue that the correlation of the observed GRB energy with the luminosity and duration of the plateau suggests that: 1) Dimmer GRBs correspond to the transport of the GRB shock through more material during breakout; and 2) Nevertheless, all GRBs energize the outgoing shock to the same energy. We suggest that these points are most consistent with the initial GRB engine occurring at different radii within the expanding SN shell as in the induced gravitational collapse paradigm.
- Publication:
-
Fourteenth Marcel Grossmann Meeting - MG14
- Pub Date:
- 2018
- DOI:
- 10.1142/9789813226609_0371
- Bibcode:
- 2018mgm..conf.2957M