Oral Presentation Astronomical Society of Australia Annual Scientific Meeting including HWWS 2013

Are Ultra-long and Sub-luminous gamma-ray bursts distinct populations ? (#37)

Eric Howell 1 , David Coward 1 , B Gendre 2 3 , G Stratta 3 , J. Atteia 4 5 , S. Basa 6 , M. Boer 7 8 , S. Cutini 2 , V. D'Elia 2 , A. klotz 4 5 , L. Piro 9
  1. University Western Australia, Perth, WA, Australia
  2. ASI Science Data Center, Galileo Galilei, I-00044 , Frascati, Italy
  3. Osservatorio Astronomico di Roma, OAR-INAF, via Frascati 33, I-00040, Monte Porzio Catone, , Rome, Italy
  4. Universit´e de Toulouse, UPS-OMP, IRAP, Toulouse, France
  5. CNRS, IRAP, 14, avenue Edouard Belin, F-31400, Toulouse, France
  6. Aix Marseille Universit´e, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388, Marseille, France
  7. CNRS, ARTEMIS, UMR 7250, Boulevard de l’Observatoire, BP 4229, F-06304 Nice Cedex 4, Nice, France
  8. CNRS, Observatoire de Haute-Provence, F-04870 Saint Michel l’Observatoire, Marseille, France
  9. Istituto di Astrofisica e Planetologia Spaziali di Roma, INAF, via fosso del cavaliere 100, I-00133, Roma, Italy

Multiwavelength observations  have shown gamma ray bursts to be the most luminous and distant transient events in the Universe. Originally categorised into two populations through their duration and spectral hardness: long/soft and short/hard;  subsequent observations have suggested the existence of a number of sub-populations of burst. These include a sub-luminous population and a recently identified ultra-long population. Using a novel approach based on the arrival time records of the bursts we show how different source populations can be untangled by virtue of their intrinsic rate densities. Furthermore, we present an analysis of GRB 111209A, a burst observed for 7 hours, and suggest that this member of an ultra-long population resulted from the collapse of a low-metallicity blue super giant star.

  1. E. Howell and D. Coward, 2013, A redshift–observation time relation for gamma-ray bursts: evidence of a distinct sub-luminous population, MNRAS, 428, 167
  2. B. Gendre, G. Stratta, J.L. Atteia, S. Basa, M. Boar, D. Coward, S. Cutini, V. D’Elia, E. Howell, A. Klotz, and L. Piro, 2013, The Utra-long gamma-ray burst 111209A: The collapse of a blue supergiant, ApJ 766, 30, 2013