The Mass of the Central Black Hole in the Nearby Seyfert Galaxy NGC5273

TL;DR

This study measures the mass of the central black hole in NGC5273 using reverberation mapping, providing a key comparison point for different black hole mass estimation techniques in a nearby galaxy.

Contribution

First reverberation-mapping based black hole mass measurement in NGC5273, enabling comparison with stellar dynamical methods in an early-type galaxy.

Findings

Black hole mass estimated at (4.7 ± 1.6) × 10^6 solar masses

NGC5273's black hole sphere of influence is at the resolution limit of current telescopes

Highlights NGC5273 as a prime target for future dynamical mass measurements

Abstract

We present the results of a reverberation-mapping program targeting NGC5273, a nearby early-type galaxy with a broad-lined active galactic nucleus. Over the course of the monitoring program, NGC5273 showed strong variability that allowed us to measure time delays in the responses of the broad optical recombination lines to changes in the continuum flux. A weighted average of these measurements results in a black hole mass determination of $M_{\rm BH} = (4.7 \pm 1.6) \times 10^6$ M$_{\odot}$. An estimate of the size of the black hole sphere of influence in NGC5273 puts it just at the limit of the resolution achievable with current ground-based large aperture telescopes. NGC5273 is therefore an important future target for a black hole mass determination from stellar dynamical modeling, especially because it is the only nearby early-type galaxy hosting an AGN with a reverberation-based mass, allowing the best comparison for the masses determined from these two techniques.