Discovery Magazine

Resolving the Critical Ambiguities of the M-sigma relation

Determining the best estimates of the masses of supermassive black holes (SMBHs) and their uncertainties is crucial for constraining the slope and scatter of the SMBH mass vs. stellar velocity dispersion (m-sigma) relation and for understanding the relation between SMBHs and their host galaxies to constrain models of the evolution of galaxies and SMBHs. We are critically evaluating the values of SMBH masses in a sample of 23 galaxies using data derived from Space Telescope Imaging Spectrograph (STIS) long-slit spectroscopy.

This study is attempting to directly achieve three significant and fundamental improvements to the form of m-sigma relation so that models of the evolution of galaxies can be more tightly constrained. First, we are using all suitable STIS long-slit data to analyze SMBH masses in an entirely homogeneous fashion. Second, we are substantially increasing the SMBH sample size with new mass estimates. Finally, we are using our state-of-the-art Schwarzschild code, which will, for the first time and independently of the modelling parameters, explore the full range of SMBH masses that give statistically acceptable fits to a given data set.

This work will result in the most accurate and reliable estimate of the form slope and scatter of the m-sigma relation; improvements to-date have only been somewhat incremental. Such a study will place important constraints on some of the most fundamental problems remaining in contemporary astrophysics, i.e., understanding the evolution of galaxies.