Radio Emission from SN 1994I in NGC 5194 (M 51) - The Best Studied Type Ib/c Radio Supernova

TL;DR

This paper provides the most comprehensive multi-frequency radio observations of the Type Ic supernova SN 1994I over eight years, demonstrating that its radio emission is primarily influenced by synchrotron self-absorption at early times.

Contribution

It offers the first detailed, long-term radio data set for a Type Ib/c supernova, confirming the dominance of synchrotron self-absorption in early radio emission.

Findings

Radio emission evolves predictably over time and frequency.

Synchrotron self-absorption dominates early radio emission.

Data set is the most complete for a Type Ib/c supernova.

Abstract

We present the results of detailed monitoring of the radio emission from the Type Ic supernova SN 1994I from 3 days after optical discovery on 1994 March 31 until eight years later at age 2927 days on 2002 April 05. The data were mainly obtained using the Very Large Array at the five wavelengths, 1.3, 2.0, 3.6, 6.2, and 21 cm, and from the Cambridge 5 km Ryle Telescope at 2.0 cm. Two additional measurements were obtained at millimeter wavelengths. This data set represents the most complete, multifrequency radio observations ever obtained for a Type Ib/c supernova. The radio emission evolves regularly in both time and frequency and is well described by established SN emission/absorption models. It is the first radio supernova with sufficient data to show that it is clearly dominated by the effects of synchrotron self-absorption at early times.