A normal supermassive black hole in NGC 1277
Graham, Alister W
Savorgnan, Giulia A. D
Medling, Anne M.
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The identification of galaxies with “overly massive” black holes requires two measurements: a black hole mass (Mbh) and a host spheroid mass (Msph,*). Here we provideOur new multi-Gaussian expansion (MGE) models and Jeans Anisotropic MGE analysis struggled to match 2 (70 pc) plus eleva 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 Re,major = 2.1 kpc, and a stellar mass of 2.7 1011 Mʘ (using M LV 11.65 * = , Martín-Navarro et al.). This mass is an order of magnitude greater than originally reported. Using the latest Mbh–n, Mbh–Msph,*, and Mbh–σ relations, the expected black hole mass is, respectively, (0.57 + 1.29-0.40) x 10⁹ Mʘ and (2.27 + 4.04-1.44) x 10⁹ Mʘ (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 √₀² + v² across the inner (±3". 8) x (±0".6) region of the galaxy. Our new multi-Gaussian expansion (MGE) models and Jeans Anisotropic MGE analysis struggled to match his extended component. Our optimal black hole mass, albeit a probable upper limit because of the disk is 1.2 × 10⁹ Mʘ (M / LV = 12.3). This is an order of magnitude smaller than originally reported and 4 times smaller than recently reported. It gives an Mbh/Msph,* 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.