Detection of a Compact Nuclear Radio Source in the Local Group Elliptical Galaxy M32

TL;DR

This study reports the first detection of a compact radio source at the nucleus of galaxy M32, likely originating from its central supermassive black hole, supported by radio and X-ray observations.

Contribution

First detection of a compact radio source in M32's nucleus, suggesting emission from its supermassive black hole, combining VLA, Chandra, and XMM-Newton data.

Findings

Detected a 47.3 μJy radio source at 6.6 GHz in M32's nucleus.

Identified radio emission from three planetary nebulae in M32.

Revised X-ray properties of the SMBH candidate in M32.

Abstract

The Local Group compact elliptical galaxy M32 hosts one of the nearest candidate super-massive black holes (SMBHs), which has a previously suggested X-ray counterpart. Based on sensitive observations taken with the {\it Karl G. Jansky} Very Large Array (VLA), we detect for the first time a compact radio source coincident with the nucleus of M32, which exhibits an integrated flux density of $\sim$$47.3\pm6.1$ $\mu$Jy at 6.6 GHz. We discuss several possibilities for the nature of this source, favoring an origin of the long-sought radio emission from the central SMBH, for which we also revisit the X-ray properties based on recently acquired {\sl Chandra} and {\sl XMM-Newton} data. Our VLA observations also discover radio emission from three previously known optical planetary nebulae in the inner region of M32.