Discovery of a very highly extinguished supernova in a luminous infrared galaxy

TL;DR

This paper reports the discovery of a highly obscured supernova in a luminous infrared galaxy using advanced adaptive optics and space telescope imaging, revealing the highest measured extinction for a supernova and confirming its core-collapse nature through radio observations.

Contribution

First supernova discovered with laser guide star adaptive optics in a luminous infrared galaxy, demonstrating the ability to detect highly obscured supernovae in nuclear regions.

Findings

Supernova 2008cs has the highest measured extinction for a supernova.

The supernova's properties are consistent with a core-collapse event.

Radio detection confirms the supernova's core-collapse nature.

Abstract

We report the discovery of a confirmed supernova (SN) and a supernova-candidate in near-infrared images from the ALTAIR/NIRI adaptive optics system on the Gemini-North Telescope and NICMOS on the Hubble Space Telescope. The Gemini images were obtained as part of a near-infrared K-band search for highly-obscured SNe in the nuclear regions of luminous infrared galaxies. SN 2008cs apparent in the Gemini images is the first SN discovered using laser guide star adaptive optics. It is located at 1500 pc projected distance from the nucleus of the luminous infrared galaxy IRAS 17138-1017. The SN luminosity, JHK colors and light curve are consistent with a core-collapse event suffering from a very high host galaxy extinction of 15.7 +- 0.8 magnitudes in V-band which is to our knowledge the highest yet measured for a SN. The core-collapse nature of SN 2008cs is confirmed by its radio detection at 22.4 GHz using our Very Large Array observations 28 days after the SN discovery, indicating a prominent interaction of the SN ejecta with the circumstellar medium. An unconfirmed SN apparent in the NICMOS images from 2004 is located in the same galaxy at 660 pc projected distance from the nucleus and has a lower extinction.