SECULAR EVOLUTION AND A NON-EVOLVING BLACK-HOLE-TO-GALAXY MASS RATIO IN THE LAST 7 Gyr

Journal Article · Tue Nov 01 04:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/741/1/L11· OSTI ID:21565348

Cisternas, Mauricio; Jahnke, Knud; Inskip, Katherine J ^[1]; Bongiorno, Angela; Merloni, Andrea ^[2]; Impey, Chris D ^[3]; Koekemoer, Anton M ^[4]; Salvato, Mara ^[5]

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1. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
2. Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei Muenchen (Germany)
3. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
5. Max-Planck-Institut fuer Plasmaphysik, Boltzmanstrasse 2, D-85741 Garching (Germany)

We present new constraints on the ratio of black hole (BH) mass to total galaxy stellar mass at 0.3 < z < 0.9 for a sample of 32 type-1 active galactic nuclei (AGNs) from the XMM-COSMOS survey covering the range M{sub BH} {approx} 10{sup 7.2-8.7} M{sub sun}. Virial M{sub BH} estimates based on H{beta} are available from the COSMOS Magellan/IMACS survey. We use high-resolution Hubble Space Telescope (HST) imaging to decompose the light of each type-1 AGN and host galaxy, and employ a specially built mass-to-light ratio to estimate the stellar masses (M{sub *}). The M{sub BH}-M{sub *} ratio shows a zero offset with respect to the local relation for galactic bulge masses, and we also find no evolution in the mass ratio M{sub BH}/M{sub *}{proportional_to}(1 + z){sup 0.02{+-}0.34} up to z {approx} 0.9. Interestingly, at the high-M{sub BH} end there is a positive offset from the z = 0 relation, which can be fully explained by a mass function bias with a cosmic scatter of {sigma}{sub {mu}} = 0.3, reaffirming that the intrinsic distribution is consistent with zero evolution. From our results we conclude that since z {approx} 0.9 no substantial addition of stellar mass is required: the decline in star formation rates and merger activity at z < 1 support this scenario. Nevertheless, given that a significant fraction of these galaxies show a disk component, their bulges are indeed undermassive. This is a direct indication that for the last 7 Gyr the only essential mechanism required for these galaxies to obey the z = 0 relation is a redistribution of stellar mass to the bulge, likely driven by secular processes, i.e., internal instabilities and minor merging.

• OSTI ID: 21565348
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 741; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
GALAXY NUCLEI
MASS
STARS