In Search Of The Largest Velocity Dispersion Galaxies

Abstract

We present Hobby-Eberly Telescope (HET) observations for galaxies at redshift z < 0:3 from the Sloan Digital Sky Survey (SDSS) showing large velocity dispersions while appearing to be single galaxies in HSTimages. The high signal-to-noise HET spectra provide more definitive velocity dispersions. The maximum velocity dispersion we find is sigma(*) = 444 km s(-1). Emission-line widths in QSOs indicate that black holes can exist with masses M-center dot exceeding 5 billion M-circle dot, implying sigma(*) > 500 km s(-1) by the local M-center dot sigma(*) relationship. This suggests either that QSO black hole masses are overestimated or that the black hole-bulge relationship changes at high black hole mass. The latter option is consistent with evidence that the increase in sigma(*) with luminosity levels off for the brightest elliptical galaxies.