A Normal Supermassive Black Hole in NGC 1277
Abstract
The identification of galaxies with “overly massive” black holes requires two measurements: a black hole mass (Mbh) and a host spheroid mass ({M}{{sph,\ast }}). Here we provide our measurements for NGC 1277. Our structural decomposition reveals that NGC 1277 is dominated by a “classical” spheroid with a Sérsic index n = 5.3, a half-light radius {R}{{e,major}}=2.1 {{kpc}}, and a stellar mass of 2.7× {10}11\quad {M}⊙ (using {M}*/{L}V=11.65, Martín-Navarro et al.). This mass is an order of magnitude greater than originally reported. Using the latest Mbh-n, Mbh-{M}{{sph,\ast }}, and Mbh-σ relations, the expected black hole mass is, respectively, ({0.57}-0.40+1.29)× {10}9\quad {M}⊙ , ({1.58}-1.13+4.04)× {10}9\quad {M}⊙ , and ({2.27}-1.44+4.04)× {10}9\quad {M}⊙ (using σ = 300 km s-1) for which the “sphere-of-influence” is 0.″31. Our new kinematical maps obtained from laser guide star assisted, adaptive optics on the Keck I Telescope dramatically reaffirm the presence of the inner, nearly edge-on, disk seen in the galaxy image. We also report that this produces a large velocity shear (∼400 km s-1) across the inner 0.″2 (70 pc) plus elevated values of \sqrt{{σ }2+{V}2} across the inner (+/- 3\buildrel{\prime\prime}\over{.} 8)× (+/- 0\buildrel{\prime\prime}\over{.} 6) region of the galaxy. Our new multi-Gaussian expansion (MGE) models and Jeans Anisotropic MGE analysis struggled to match this extended component. Our optimal black hole mass, albeit a probable upper limit because of the disk is 1.2 × 109 M⊙ (M/{L}V=12.3). This is an order of magnitude smaller than originally reported and 4 times smaller than recently reported. It gives an {M}{{bh}}/{M}{{sph,\ast }} ratio of 0.45% in agreement with the median (≈0.5%) and range (0.1%-5.0%) observed in non-dwarf, early-type galaxies. This result highlights the need for caution with inner disks.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2016
- DOI:
- 10.3847/0004-637X/819/1/43
- arXiv:
- arXiv:1601.05151
- Bibcode:
- 2016ApJ...819...43G
- Keywords:
-
- black hole physics;
- galaxies: individual: NGC 1277;
- galaxies: kinematics and dynamics;
- galaxies: nuclei;
- galaxies: photometry;
- galaxies: structure;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted to appear in ApJ (originally submitted 19 August, 2015). 15 pages (including 11 figures and 1 page of references)