2004/02/29 by A. M. Soderberg, D. A. Frail, M. H. Wieringa · 5 citations
Engineering · Physics and Astronomy · #Astrophysical jet #Astrophysics and Cosmic Phenomena #CCD and CMOS Imaging Sensors #Gamma-ray burst #Gamma-ray bursts and supernovae #Jet (fluid) #Line (geometry) #Shock (circulatory) #Shock wave #Supernova #Type (biology) #astro-ph
paper · pdf · doi:10.1086/421722
published as Astrophys.J. 607 (2004) L13 · Revised version, as it appears in ApJL
openalex publication_date 2004/04/27 · arxiv created 2005/12/06 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
It has been suggested that the peculiar properties of the luminous Type Ic supernova SN 1998bw and its low-energy gamma-ray burst GRB 980425 may be understood if they originated in a standard gamma-ray burst explosion viewed far from the axis of the relativistic jet. In this scenario, strong radio emission is predicted from the jet on a timescale 1-10 yr after the explosion as it decelerates and spreads into our line of sight. To test this hypothesis, we have carried out late-time radio observations of SN 1998bw at t = 5.6 yr, yielding upper limits that are consistent with the continued fading of the supernova. We find these limits to be consistent with an off-axis jet only if the progenitor mass-loss rate is ≲ 4 × 10 -7 M ☉ yr -1 (for a wind velocity v w = 1000 km s -1 ) or the fraction of the shock energy in magnetic fields is B ≲ 10 -3 . These values are low relative to those inferred for cosmological gamma-ray bursts. We combine the SN 1998bw measurements with existing observations for a sample of 15 local Type Ibc supernovae to estimate that at most 6% produce collimated, relativistic outflows.