Disappearance of the Progenitor of Supernova iPTF13bvn

TL;DR

This study confirms the disappearance of the supernova progenitor in pre-explosion images through deep UV and optical observations, refining models of its binary nature and highlighting the need for further data.

Contribution

The paper provides direct observational evidence of the progenitor's disappearance and refines progenitor models by incorporating deep UV and optical data.

Findings

The progenitor candidate has faded significantly, confirming its association with the supernova.

Binary progenitor models are favored but require refinement to match UV constraints.

Further observations are needed to fully characterize the progenitor and its environment.

Abstract

Supernova (SN) iPTF13bvn in NGC 5806 was the first Type Ib SN to have been tentatively associated with a progenitor candidate in pre-explosion images. We performed deep ultraviolet (UV) and optical Hubble Space Telescope (HST) observations of the SN site 740 days after explosion. We detect an object in the optical bands that is fainter than the pre-explosion object. This dimming is likely not produced by dust absorption in the ejecta; thus, our finding confirms the connection of the progenitor candidate with the SN. The object in our data is likely dominated by the fading SN, which implies that the pre-SN flux is mostly due to the progenitor. We compare our revised pre-SN photometry with previously proposed progenitor models. Although binary progenitors are favored, models need to be refined. In particular, to comply with our deep UV detection limit, any companion star must be less luminous than a late-O star or substantially obscured by newly formed dust. A definitive progenitor characterization will require further observations to disentangle the contribution of a much fainter SN and its environment.