Detection of a thermal spectral component in the prompt emission of GRB 100724B

Sylvain Guiriec, Valerie Connaughton, Michael S. Briggs, Michael Burgess, Felix Ryde, Frédéric Daigne, Peter Mészáros, Adam Goldstein, Julie McEnery, Nicola Omodei, P. N. Bhat, Elisabetta Bissaldi, Ascensión Camero-Arranz, Vandiver Chaplin, Roland Diehl, Gerald Fishman, Suzanne Foley, Melissa Gibby, Misty M. Giles, Jochen GreinerDavid Gruber, Andreas Von Kienlin, Marc Kippen, Chryssa Kouveliotou, Sheila McBreen, Charles A. Meegan, William Paciesas, Robert Preece, Arne Rau, Dave Tierney, Alexander J. Van Der Horst, Colleen Wilson-Hodge

Research output: Contribution to journalArticlepeer-review

215 Scopus citations


Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor find that the spectrum is dominated by the typical Band functional form, which is usually taken to represent a non-thermal emission component, but also includes a statistically highly significant thermal spectral contribution. The simultaneous observation of the thermal and non-thermal components allows us to confidently identify the two emission components. The fact that these seem to vary independently favors the idea that the thermal component is of photospheric origin while the dominant non-thermal emission occurs at larger radii. Our results imply either a very high efficiency for the non-thermal process or a very small size of the region at the base of the flow, both quite challenging for the standard fireball model. These problems are resolved if the jet is initially highly magnetized and has a substantial Poynting flux.

Original languageEnglish (US)
JournalAstrophysical Journal Letters
Issue number2 PART II
StatePublished - Feb 1 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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