Supermassive Black Holes and Their Host Spheroids. II. The Red and Blue Sequence in the MBH-M*,sph Diagram

Journal
Date Issued
2016
Author(s)
Savorgnan, Giulia A. D.
•
Graham, Alister W.
•
•
Sani, Eleonora
DOI
Abstract
In our first paper, we performed a detailed (I.e., bulge, disks, bars, spiral arms, rings, halo, nucleus, etc.) decomposition of 66 galaxies, with directly measured black hole masses, MBH, imaged at 3.6 μ {{m}} with Spitzer. Our sample is the largest to date and, for the first time, the decompositions were checked for consistency with the galaxy kinematics. We present correlations between MBH and the host spheroid (and galaxy) luminosity, Lsph (and Lgal), and also stellar mass, {M}*,{sph}. While most previous studies have used galaxy samples that were overwhelmingly dominated by high-mass, early-type galaxies, our sample includes 17 spiral galaxies, half of which have {M}{BH}\lt {10}7 {M}☉ , and allows us to better investigate the poorly studied low-mass end of the {M}{BH}{--}{M}*,{sph} correlation. The bulges of early-type galaxies follow {M}{BH} \propto \{M}*,{sph}1.04+/- 0.10 and define a tight red sequence with intrinsic scatter {∊ }({M{BH}| {M}*,{sph})}\quad =\quad 0.43\quad +/- \quad 0.06 {dex} and a median {M}{BH}/{M}*,{sph} ratio of 0.68 ± 0.04%, I.e., a +/- 2σ range of 0.1%-5%. At the low-mass end, the bulges of late-type galaxies define a much steeper blue sequence, with {M}{BH} \propto {M}*,{sph}2-3 and {M}{BH}/{M}*,{sph} equal to 0.02% at {M}{BH} ≈ {10}6 {M}☉ . We additionally report that (1) our Sérsic galaxy sample follows {M}{BH} \propto \{M}*,{sph}1.48+/- 0.20, a less steep sequence than previously reported; (2) bulges with Sérsic index {n}{sph}\lt 2, argued by some to be pseudo-bulges, are not offset to lower MBH from the correlation defined by the current bulge sample with {n}{sph}\gt 2; and (3) Lsph and Lgal correlate equally well with MBH, in terms of intrinsic scatter, only for early-type galaxies—once reasonable numbers of spiral galaxies are included, the correlation with Lsph is better than that with Lgal.
Volume
817
Issue
1
Start page
21
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...817...21S
Rights
open.access
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