A relativistic type Ibc supernova without a detected Gamma-ray burst

A. M. Soderberg (1), S. Chakraborti (2), G. Pignata (3), R. A. Chevalier (4), P. Chandra (5), A. Ray (2), M. H. Wieringa (6), A. Copete (1), V. Chaplin (7), V. Connaughton (7), S. D. Barthelmy (8), M. F. Bietenholz (9,10), N. Chugai (11), M. D. Stritzinger (12,13), M. Hamuy (3), C. Fransson (14), O. Fox (4), E. M. Levesque (1,15), J. E. Grindlay (1), P. Challis (1), R. J. Foley (1), R. P. Kirshner (1), P. A. Milne (16) and M. A. P. Torres (1)

1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, Massachusetts 02138, USA
2. Tata Institute of Fundamental Research, Mumbai 400 005, India
3. Departamento de Astronomi'a, Universidad de Chile, Casilla 36-D, Santiago, Chile
4. University of Virginia, Department of Astronomy, PO Box 400325, Charlottesville, Virginia 22904, USA
5. Royal Military College of Canada, Kingston, Ontario, Canada K7K 7B4
6. Australia Telescope National Facility, CSIRO, Epping 2121, Australia
7. University of Alabama, Huntsville, Alabama 35899, USA
8. NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
9. Department of Physics and Astronomy, York University, Toronto, Ontario, Canada M3J 1P3
10. Hartebeestehoek Radio Observatory, PO Box 443, Krugersdorp, 1740, South Africa
11. Institute of Astronomy, RAS, Pyatnitskaya 48, Moscow 119017, Russia
12. Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena, Chile
13. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Copenhagen, Denmark
14. Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
15. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA
16. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, Arizona 85721, USA

Long duration Gamma-ray bursts (GRBs) mark the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. They are distinguished by the production of an energetic and collimated relativistic outflow powered by a central engine (an accreting black hole or neutron star). Observationally, this outflow is manifested in the pulse of Gamma-rays and a long-lived radio afterglow. Until now, central-engine-driven supernovae have been discovered exclusively through their Gamma-ray emission, yet it is expected that a larger population goes undetected because of limited satellite sensitivity or beaming of the collimated emission away from our line of sight. In this framework, the recovery of undetected GRBs may be possible through radio searches for type Ibc supernovae with relativistic outflows. Here we report the discovery of luminous radio emission from the seemingly ordinary type Ibc SN 2009bb, which requires a substantial relativistic outflow powered by a central engine. A comparison with our radio survey of type Ibc supernovae reveals that the fraction harbouring central engines is low, about one per cent, measured independently from, but consistent with, the inferred rate of nearby GRBs. Independently, a second mildly relativistic supernova has been reported.

Reference: Nature, Volume 463, Issue 7280, pp. 513-515 (2010).
Status: Manuscript has been accepted

Weblink: http://www.nature.com/nature/journal/v463/n7280/abs/nature08714.html


Email: sayan@tifr.res.in