Toward Precision Measurement of Central Black Hole Masses

TL;DR

This paper reviews methods for measuring supermassive black hole masses, emphasizing reverberation mapping results, their precision, and potential systematic uncertainties in calibration.

Contribution

It provides a comprehensive review of direct and indirect black hole mass measurement techniques, highlighting the small intrinsic scatter in key relationships and discussing calibration challenges.

Findings

Intrinsic scatter in AGN luminosity and BLR size is ~0.11 dex.

Reverberation-based black hole masses correlate tightly with host galaxy bulge luminosities (~0.17 dex scatter).

Potential systematics could affect mass calibration by a factor of a few.

Abstract

We review briefly direct and indirect methods of measuring the masses of black holes in galactic nuclei, and then focus attention on supermassive black holes in active nuclei, with special attention to results from reverberation mapping and their limitations. We find that the intrinsic scatter in the relationship between the AGN luminosity and the broad-line region size is very small, ~0.11 dex, comparable to the uncertainties in the better reverberation measurements. We also find that the relationship between reverberation-based black hole masses and host-galaxy bulge luminosities also seems to have surprisingly little intrinsic scatter, ~0.17 dex. We note, however, that there are still potential systematics that could affect the overall mass calibration at the level of a factor of a few.