# Investigating the Candidate Displaced Active Galactic Nucleus in NGC 3115

## TL;DR

This study uses high-sensitivity radio imaging to investigate a candidate displaced AGN in NGC 3115, finding no evidence for a secondary active nucleus and suggesting the radio source is centrally located.

## Contribution

The paper provides new sensitive radio observations that challenge previous claims of an offset AGN in NGC 3115, clarifying the nuclear structure of the galaxy.

## Key findings

- Only one AGN detected in radio imaging.
- Stringent upper limit on secondary black hole radio luminosity.
- Radio source is consistent with being at the galaxy's center.

## Abstract

The nearby galaxy NGC 3115 contains a known radio-emitting, low-luminosity active galactic nucleus (AGN), and was recently claimed to host a candidate AGN displaced 14.3 pc from the galaxy's optical photocenter. Our goal is to understand whether this represents a single offset AGN, an AGN in orbit around a central black hole, or something else. We present a new, sensitive (RMS = 4.4 $\mu$Jy beam$^{-1}$) 10 GHz image, which finds evidence for only one AGN. We place a stringent limit on the radio luminosity of any secondary supermassive black hole of $L_{10~\rm{GHz}}<5.8\times10^{33}$ ergs/s. An analysis of the relative positioning of the radio core, X-ray nucleus, and stellar bulge in this galaxy indicate that the radio source is centrally located, and not offset from the galactic bulge. This provides an argument against a single offset AGN in NGC 3115, however does not provide conclusive evidence against the purported offset AGN as an in-spiralling secondary black hole.