SDSS-RM project: velocity dispersions of QSOs

High signal-to-noise ratio coadded spectra (average S/N~30 per 69km/s pixel) from SDSS-RM allowed for the decomposition of the host and quasar spectra and for measurements of the host stellar velocity dispersions and black hole (BH) masses using the single-epoch (SE) virial method.

The large sample size and dynamic range in luminosity (L_5100_=10^43.2-44.7^erg/s) lead to the first clear detection of a correlation between SE virial BH mass and host stellar velocity dispersion far beyond the local universe. However, the observed correlation is significantly flatter than the local relation, suggesting that there are selection biases in high-z luminosity-threshold quasar samples for such studies. Our uniform sample and analysis enable an investigation of the redshift evolution of the M_{dot}_-{sigma}_*_ relation relatively free of caveats by comparing different samples/analyses at disjoint redshifts.