VLBI observations of SN2011dh: imaging of the youngest radio supernova

TL;DR

This paper presents VLBI imaging of the very young radio supernova SN2011dh at 22GHz, providing high-precision coordinates and flux measurements shortly after discovery, marking it as the youngest radio supernova imaged to date.

Contribution

It reports the first VLBI detection and imaging of SN2011dh just 14 days after explosion, with revised precise coordinates and flux comparison to EVLA data.

Findings

VLBI detected SN2011dh at 22GHz 14 days post-discovery

Revised supernova coordinates with milli-arcsecond accuracy

Flux density discrepancy suggests extended emission or calibration issues

Abstract

We report on the VLBI detection of supernova SN2011dh at 22GHz using a subset of the EVN array. The observations took place 14 days after the discovery of the supernova, thus resulting in a VLBI image of the youngest radio-loud supernova ever. We provide revised coordinates for the supernova with milli-arcsecond precision, linked to the ICRF. The recovered flux density is a factor 2 below the EVLA flux density reported by other authors at the same frequency and epoch of our observations. This discrepancy could be due to extended emission detected with the EVLA or to calibration problems in the VLBI and/or EVLA observations.