The metamorphosis of Supernova SN2008D/XRF080109: a link between Supernovae and GRBs/Hypernovae

TL;DR

SN 2008D exhibits unique features linking supernovae and gamma-ray bursts, showing that even weaker explosions can produce relativistic jets during black hole formation in massive star collapses.

Contribution

This paper presents detailed analysis of SN 2008D, revealing it as an intermediate case between normal supernovae and hypernovae, and suggests a connection between black hole formation and jet production.

Findings

SN 2008D had an explosion energy of ~6*10^{51} erg.

It originated from a ~30Msun star collapsing into a black hole.

A weak, mildly relativistic jet caused the observed XRF.

Abstract

The only supernovae (SNe) to have shown early gamma-ray or X-ray emission thus far are overenergetic, broad-lined Type Ic SNe (Hypernovae - HNe). Recently, SN 2008D shows several novel features: (i) weak XRF, (ii) an early, narrow optical peak, (iii) disappearance of the broad lines typical of SNIc HNe, (iv) development of He lines as in SNeIb. Detailed analysis shows that SN 2008D was not a normal SN: its explosion energy (KE ~ 6*10^{51} erg) and ejected mass (~7 Msun) are intermediate between normal SNeIbc and HNe. We derive that SN 2008D was originally a ~30Msun star. When it collapsed a black hole formed and a weak, mildly relativistic jet was produced, which caused the XRF. SN 2008D is probably among the weakest explosions that produce relativistic jets. Inner engine activity appears to be present whenever massive stars collapse to black holes.