Black-Hole-Spheroid Mass Relation

arXiv:1102.1975 [pdf, ps, other]

The Relation between Black Hole Mass and Host Spheroid Stellar Mass out to z~2

Vardha Nicola Bennert (1), Matthew W. Auger (1), Tommaso Treu (1), Jong-Hak Woo (2), Matthew A. Malkan (3) ((1) UCSB, (2) Seoul National University, (3) UCLA)

Comments: 7 pages, 3 figures. Submitted to the Astrophysical Journal Letters

Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)

We combine Hubble Space Telescope images from the Great Observatories Origins Deep Survey with archival Very Large Telescope and Keck spectra of a sample of 11 X-ray selected broad-line active galactic nuclei in the redshift range 1<z<2 to study the black hole mass - stellar mass relation out to a lookback time of 10 Gyrs. Stellar masses of the spheroidal component are derived from multi-filter surface photometry. Black hole masses are estimated from the width of the broad MgII emission line and the 3000A nuclear luminosity. We find evolution in the form M_BH/M_spheroid ~ (1+z)^(2.1+/-0.3), in agreement with our earlier studies based on spheroid luminosity. However, this result is more accurate because it does not require a correction for luminosity evolution and therefore avoids the related and dominant systematic uncertainty. We also measure total stellar masses. Combining our sample with data from the literature, we find M_BH/M_host ~ (1+z)^(1.41+/-0.12), consistent with the hypothesis that black holes (in the range M_BH ~ 10^8-9 M_sun) predate the formation of their host galaxies. Roughly one third of our objects reside in spiral galaxies with the majority showing no evidence of a bulge component; none of the host galaxies reveal signs of interaction or merger activity. Combined, our results indicate that secular evolution plays a non-negligible role in growing spheroids.