GRB 101225A: a stellar murder on Christmas Day

Dr. Miguel Ángel Aloy

Abstract

Long Gamma-Ray Bursts (GRBs) are the most dramatic examples of massive stellar deaths, usually associated with supernovae (Woosley et al. 2006). They release ultra-relativistic jets producing non-thermal emission through synchrotron radiation as they interact with the surrounding medium (Zhang et al. 2004). Here we report observations of the peculiar GRB 101225A (the "Christmas burst"). Its gamma-ray emission was exceptionally long and followed by a bright X-ray transient with a hot thermal component and an unusual optical counterpart. During the first 10 days, the optical emission evolved as an expanding, cooling blackbody after which an additional component, consistent with a faint supernova, emerged. We determine its distance to 1.6 Gpc by fitting the spectral-energy distribution and light curve of the optical emission with a GRB-supernova template. Deep optical observations may have revealed a faint, unresolved host galaxy. Our proposed progenitor is a helium star-neutron star merger that underwent a common envelope phase expelling its hydrogen envelope. The resulting explosion created a GRB-like jet which gets thermalized by interacting with the dense, previously ejected material and thus creating the observed black-body, until finally the emission from the supernova dominated. An alternative explanation is a minor body falling onto a neutron star in the Galaxy (Campana et al. 2011).

About the talk

GRB 101225A: a stellar murder on Christmas Day
Dr. Miguel Ángel Aloy
University of Valencia, Spain
Thursday December 15, 2011 - 0:00  (Aula)
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For nature article see Thone et al. (2011, Nat, 480, 72). For related arcticles see Campana et al. (2011, Nat, 480, 69). For "News and View" see Costa et al. (2011, Nat, 480, 47).