Disky elliptical galaxies and the allegedly over-massive black hole in the compact massive `ES' galaxy NGC 1271 (1608.00711v2)

Abstract: While spiral and lenticular galaxies have large-scale disks extending beyond their bulges, and most local early-type galaxies with 10^{10} < M_/M_Sun < 2x10^{11} contain a disk (e.g., ATLAS^3D), the early-type galaxies do possess a range of disk sizes. The edge-on, intermediate-scale' disk in thedisky elliptical' galaxy NGC 1271 has led to some uncertainty as to what its spheroidal component is. Walsh et al. reported a directly measured black hole mass of 3x10^9 M_Sun for this galaxy; which they remarked was an order of magnitude greater than what they expected based on their derivation of the host spheroid's luminosity. Our near-infrared image analysis supports a small embedded disk within a massive spheroidal component with M_{sph,} = (0.9+/-0.2)x10^{11} M_Sun (using M_/L_H = 1.4 from Walsh et al.). This places NGC 1271 just 1.6-sigma above the near-linear M_bh-M_{sph,} relation for early-type galaxies. Therefore, past speculation that there may be a systematic difference in the black hole scaling relations between compact massive early-type galaxies with intermediate-scale disks, i.e. ES galaxies such as NGC 1271, and early-type galaxies with either no substantial disk (E) or a large-scale disk (S0) is not strongly supported by NGC 1271. We additionally (i) show how ES galaxies fit naturally in the (`bulge'-to-total)-(morphological type) diagram, while noting a complication with recent revisions to the Hubble-Jeans tuning-fork diagram, (ii) caution about claims of over-massive black holes in other ES galaxies if incorrectly modelled as S0 galaxies, and (iii) reveal that the compact massive spheroid in NGC 1271 has properties similar to bright bulges in other galaxies which have grown larger-scale disks.