Astronomy and Astrophysics – Astrophysics
Scientific paper
1999-03-31
Astronomy and Astrophysics
Astrophysics
21 pages, 9 figures, revised version to appear in ApJ
Scientific paper
10.1086/308031
SN 1998bw is an unusual Type Ic supernova that may be associated with the $\gamma$-ray burst GRB 980425. We use a synchrotron self-absorption model for its radio emission to deduce that the synchrotron-emitting gas is expanding into a circumstellar medium of approximately $r^{-2}$ density profile, at a speed comparable to the speed of light. We assume that the efficiencies of production of relativistic electrons and magnetic field are constant through the evolution. The circumstellar density is consistent with that expected around the massive star core thought to be the progenitor of SN 1998bw. The explosion energy in material moving with velocity $>0.5c$ is $\sim 10^{49}- 3\times 10^{50}$ ergs, with some preference for the high values. The rise in the radio light curves observed at days 20-40 is inferred to be the result of a rise in the energy of the blast wave by a factor $\sim 2.5$. Interaction with a jump in the ambient density is not consistent with the observed evolution. We infer that the boost in energy is from a shell of matter from the explosion that catches up with the decelerating shock front. Both the high explosion energy and the nature of the energy input to the blast wave are difficult to reconcile with energy input from the shock-accelerated high velocity ejecta from a supernova. The implication is that there is irregular energy input from a central engine, which is the type of model invoked for normal $\gamma$-ray bursts. The link between SN 1998bw and GRB 980425 is thus strengthened.
Chevalier Roger A.
Li Zhi-Yun
No associations
LandOfFree
Radio Supernova SN 1998bw and Its Relation to GRB 980425 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Radio Supernova SN 1998bw and Its Relation to GRB 980425, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radio Supernova SN 1998bw and Its Relation to GRB 980425 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-486803