---
abstract: 'It has been established that virial masses for black holes in low-redshift active galaxies can be estimated from measurements of the optical continuum strength and the width of the broad [H$\beta$]{} line. Under various circumstances, however, both of these quantities can be challenging to measure or can be subject to large systematic uncertainties. To mitigate these difficulties, we present a new method for estimating black hole masses. From analysis of a new sample of broad-line active galactic nuclei, we find that [H$\alpha$]{} luminosity scales almost linearly with optical continuum luminosity and that a strong correlation exists between [H$\alpha$]{} and [H$\beta$]{} line widths. These two empirical correlations allow us to translate the standard virial mass system to a new one based solely on observations of the broad [H$\alpha$]{} emission line.'
author:
- 'Jenny E. Greene'
- 'Luis C. Ho'
title: 'Estimating Black Hole Masses in Active Galaxies Using the [H$\alpha$]{} Emission Line'
---

Introduction
============

The recent discovery of a tight correlation between black hole (BH) mass and the stellar velocity dispersion of the bulge of the host galaxy (the [$M_{\mathrm{BH}}-{\ensuremath{\sigma_{\ast}}}$]{} relation; Gebhardt [et al.]{} 2000a; Ferrarese & Merritt 2000) has sparked renewed interest in deriving BH masses in 