The Spectroscopic Classification and Explosion Properties of SN2009nz Associated with GRB091127 at z=0.490

Understand

We present spectroscopic observations of GRB091127 (z=0.490) at the peak of the putative associated supernova, SN2009nz.

• Subtracting a late-time spectrum of the host galaxy, we isolate the contribution of SN2009nz and uncover broad features typical of nearby GRB-SNe.
• This establishes unambiguously that GRB091127 was accompanied by a broad-lined Type Ic SN, and links a cosmological long burst with a standard energy release (E_gamma,iso ~ 1.1e52 erg) to a massive star progenitor.
• The spectrum of SN2009nz closely resembles that of SN2006aj, with SN2003dh also providing an acceptable match, but has significantly narrower features than SNe 1998bw and 2010bh, indicative of a lower expansion velocity.