Outliers from the mainstream: how a massive star can produce a gamma-ray burst

Abstract

It is now recognized that long-duration Gamma-Ray Bursts (GRBs) are linked to the collapse of massive stars, based on the association between (low-redshift) GRBs and (type Ic) core-collapse supernovae (SNe). The census of massive stars and GRBs reveals, however, that not all massive stars do produce a GRB. Only ~1% of core collapse SNe are able to produce a highly relativistic collimated outflow, and hence a GRB. The extra crucial parameter has long been suspected to be metallicity and/or rotation. We find observational evidence strongly supporting that both ingredients are necessary in order to make a GRB out of a core-collapsing star. A detailed study of the absorption pattern in the X-ray spectrum of GRB060218 reveals evidence of material highly enriched in low atomic number metals ejected before the SN/GRB explosion. We find that, within the current scenarios of stellar evolution, only a progenitor star characterized by a fast stellar rotation and sub-solar initial metallicity could produce such a metal enrichment in its close surrounding.

ApJL in press 4 pages 2 figures

References in corpus (11)

• The Supernova -- Gamma-Ray Burst Connection
• Long gamma-ray bursts and core-collapse supernovae have different environments
• An optical supernova associated with the X-ray flash XRF 060218
• A giant outburst two years before the core-collapse of a massive star
• A neutron-star-driven X-ray flash associated with supernova SN 2006aj
• GRB 060218/SN 2006aj: A Gamma-Ray Burst and Prompt Supernova at z=0.0335
• Supernova 2006aj and the associated X-Ray Flash 060218
• SN 2006aj and the nature of low-luminosity gamma-ray bursts
• Very different X-ray to optical column density ratios in gamma-ray burst afterglows: ionisation in GRB environments
• Long Term Radio Monitoring of SN 1993J
• The nature of the dwarf starforming galaxy associated with GRB 060218 / SN2006aj

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• Gamma-Ray Bursts as a Threat to Life on Earth
• Time domain astrophysics with transient sources. Delay estimate via Cross Correlation Function techniques
• XIAO: a soft X-ray telescope for the SVOM Mission