SN 2007it on the RISE -- a radio detection of an interacting supernova 18 years post-explosion

TL;DR

This paper reports the first radio detection of supernova SN 2007it 18 years post-explosion, revealing late-time interaction with circumstellar material and highlighting the importance of long-term monitoring.

Contribution

It presents the first radio detection of SN 2007it after 18 years, demonstrating late-time emission and encouraging multi-wavelength follow-up observations.

Findings

Detected radio emission at 5.5 and 9.0 GHz 18 years after explosion.

Non-detection at 0.88 GHz suggests possible rapid emission rise or absorption.

Highlights potential for late-time radio observations of supernovae.

Abstract

We report the first detection of radio emission from the Type II supernova SN 2007it, located at a distance of 12.2 Mpc in NGC 5530. The observations were obtained with the Australian Telescope Compact Array (ATCA) more than 18 yr after the explosion as part of the Rebrightening in Interacting Supernova Emission (RISE) program, which monitors nearby core-collapse supernovae for late-time interaction with dense circumstellar material. SN 2007it was detected on 2026 April 8 (08:00-12:00 UTC) at 5.5 GHz with a flux density of $3.30 \pm 0.13$ mJy and at 9.0 GHz with $3.54 \pm 0.24$ mJy. Its non-detection in publicly available 0.88 GHz ASKAP data from 2026 January 11 suggests either rapidly rising emission or significant internal absorption at lower frequencies. We assess the prospects for detection at other wavelengths and encourage coordinated follow-up observations across the radio, optical, X-ray, and $\gamma$-ray band