Abstract
We measure the correlation between black-hole mass $M_BH$ and host
stellar mass $M_*$ for a sample of 38 broad-line quasars at $0.2łesssim
z0.8$ (median redshift $z_med=0.5$). The black-hole masses are
derived from a dedicated reverberation mapping program for distant quasars, and
the stellar masses are estimated from two-band optical+IR HST imaging. Most of
these quasars are well centered within $1$kpc from the host galaxy
centroid, with only a few cases in merging/disturbed systems showing larger
spatial offsets. Our sample spans two orders of magnitude in stellar mass
($10^9-10^11\,M_ødot$) and black-hole mass ($10^7-10^9\,M_ødot$),
and reveals a significant correlation between the two quantities. We find a
best-fit intrinsic (i.e., selection effects corrected) $M_BH-M_\rm
*,host$ relation of $(M_BH/M_ødot)=7.01_-0.33^+0.23 +
1.74_-0.64^+0.64(M_*,host/10^10M_ødot)$, with an
intrinsic scatter of $0.47_-0.17^+0.24$dex. Decomposing our quasar hosts
into bulges and disks, there is a similar $M_BH-M_*,bulge$ relation
with a slightly larger scatter, likely caused by systematic uncertainties in
the bulge-disk decomposition. The $M_BH-M_*,host$ relation at
$z_med=0.5$ is similar to that in local quiescent galaxies, with
negligible evolution over the redshift range probed by our sample. With direct
black-hole masses from reverberation mapping and a large dynamical range of the
sample, selection biases do not appear to affect our conclusions significantly.
Our results, along with other samples in the literature, suggest that the
locally-measured black-hole mass$-$host stellar mass relation is already in
place at $z1$.
Description
The Sloan Digital Sky Survey Reverberation Mapping Project: The Black Hole Mass$-$Stellar Mass Relations at $0.2\lesssim z\lesssim 0.8$
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