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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20111215T000000
DTEND;TZID=Atlantic/Canary:20111215T010000
UID:iactalks-322
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/322
CREATED:2011-12-15T00:00:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:GRB 101225A: a stellar murder on Christmas Day
DESCRIPTION:GRB 101225A: a stellar murder on Christmas Day\nDr. Miguel Áng
 el Aloy\n\nLong 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 emissio
 n through synchrotron radiation as they interact with the surrounding medi
 um (Zhang et al. 2004). Here we report observations of the peculiar GRB 10
 1225A (the "Christmas burst"). Its gamma-ray emission was exceptionally lo
 ng and followed by a bright X-ray transient with a hot thermal component a
 nd an unusual optical counterpart. During the first 10 days, the optical e
 mission evolved as an expanding, cooling blackbody after which an addition
 al  component, consistent with a faint supernova, emerged. We determine it
 s distance to 1.6 Gpc by fitting the spectral-energy distribution and ligh
 t curve of the optical emission with a GRB-supernova template. Deep optica
 l observations may have revealed a faint, unresolved host galaxy. Our prop
 osed progenitor is a helium star-neutron star merger that underwent a comm
 on envelope phase expelling its hydrogen envelope. The resulting explosion
  created a GRB-like jet which gets thermalized by interacting with the den
 se, 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 (Cam
 pana et al. 2011).
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