Black Hole Mass Scaling Relations for Early-type Galaxies. I. M BH-M ∗, sph and M BH-M ∗,gal

Nandini Sahu, Alister W. Graham, Benjamin L. Davis

    Research output: Contribution to journalArticlepeer-review


    Analyzing a sample of 84 early-type galaxies (ETGs) with directly measured supermassive black hole masses-nearly doubling the sample size of such galaxies with multicomponent decompositions-a symmetric linear regression on the reduced (merger-free) sample of 76 galaxies reveals MBH ∝ M1.27 ±;0.07∗,sph with a total scatter of Δrms = 0.52 dex in the log(MBH) direction. Importantly, however, we discover that the ES/S0-type galaxies with disks are offset from the E-type galaxies by more than a factor of ten in their MBH/M∗,sph ratio, with ramifications for formation theories, simulations, and some virial factor measurements used to convert AGN virial masses into MBH. Separately, each population follows a steeper relation with slopes of 1.86 ±; 0.20 and 1.90 ±; 0.20, respectively. The offset mass ratio is mainly due to the exclusion of the disk mass, with the two populations offset by only a factor of two in their MBH/M∗,gal ratio in the MBH-M∗,gal diagram where MBH ∝ M∗,gal 1.8±; 0.2and Δrms = 0.6 ±; 0.1 dex depending on the sample. For MBH ≳107Mo, we detect no significant bend nor offset in either the MBH-M∗,sph or MBH-M∗,gal relations due to barred versus non-barred, or core-Sersic versus Sersic, ETGs. For reference, the ensemble of late-type galaxies (which invariably are Sersic galaxies) follow MBH-M∗,sph and MBH-M∗,gall relations with slopes equal to 2.16±;0.32 and 3.05±;00.70, respectively. Finally, we provide some useful conversion coefficients, ν, accounting for the different stellar mass-to-light ratios used in the literature, and we report the discovery of a local, compact massive spheroid in NGC 5252.

    Original languageEnglish (US)
    Article number155
    JournalAstrophysical Journal
    Issue number2
    StatePublished - May 10 2019


    • black hole physics
    • galaxies: bulges
    • galaxies: elliptical and lenticular, cD
    • galaxies: evolution
    • galaxies: photometry
    • galaxies: structure

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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