Discovery of a Relativistic Supernova Without a Gamma-ray Trigger
2009 (English)Other (Other (popular science, discussion, etc.))
Type Ibc supernovae (SNe Ibc) mark the gravitational collapse of some massive stars (M > 20 Msun) propelling several solar masses of material to typical velocities of ~10,000 km/s. The closely-related but exceedingly rare class of long-duration gamma-ray bursts (GRBs) produce, in addition, a relativistic outflow powered by a central engine (accreting black hole or neutron star) and have been found exclusively through their gamma-ray signal. Here we report the discovery of luminous radio emission from the seemingly ordinary Type Ibc SN 2009bb which outshines that of all other SNe Ibc observed on a comparable timescale. These observations require a substantial mildly-relativistic outflow and indicate that the explosion was powered by a central engine, thus representing the first such event discovered without the aid of a gamma-ray trigger. A comparison with our extensive radio survey of SNe Ibc reveals that the fraction of such events is low (roughly 1 percent), measured independently from, and yet consistent with, the inferred rate of nearby GRBs. This discovery marks the observational realization that long-wavelength surveys will soon rival gamma-ray satellites in pinpointing nearby engine-driven explosions.
Place, publisher, year, edition, pages
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
IdentifiersURN: urn:nbn:se:su:diva-36303OAI: oai:DiVA.org:su-36303DiVA: diva2:289178