2008/05/01 by Davide Lazzati, Rosalba Perna, Mitchell C. Begelman · 36 citations
Physics and Astronomy · #Accretion (finance) #Afterglow #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Flare #Galaxy #Gamma-ray burst #Gamma-ray bursts and supernovae #Jet (fluid) #Luminosity #Mechanics #Neutrino #Nuclear physics #Outflow #Physics #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1111/j.1745-3933.2008.00490.x
published in Monthly Notices of the Royal Astronomical Society Letters 388(1), L15-L19 (Oxford University Press) · 5 pages, MNRAS in press
arxiv created 2008/05/01 · openalex publication_date 2008/06/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract We compute the average luminosity of X-ray flares as a function of time, for a sample of 10 long-duration gamma-ray burst (GRB) afterglows. The mean luminosity, averaged over a time-scale longer than the duration of the individual flares, declines as a power law in time with index approximately -1.5. We elaborate on the properties of the central engine that can produce such a decline. Assuming that the engine is an accreting compact object, and for a standard conversion factor between accretion rate and jet luminosity, the switch between a neutrino-cooled thin disc and a non-cooled thick disc takes place at the transition from the prompt to the flaring phase. We discuss the implications of this coincidence under different scenarios for the powering of the GRB outflow. We also show that the interaction of the outflow with the envelope of the progenitor star cannot produce flares out of a continuous relativistic flow, and conclude that it is the dynamics of the disc or the jet launching mechanism that generates an intrinsically unsteady outflow on time-scales much longer than the dynamical time-scale of the system. This is consistent with the fact that X-ray flares are observed in short-duration GRBs as well as in long-duration ones.