Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei and the First Black Hole Determination for NGC 205

• Published in: The Astrophysical journal Vol. 872; no. 1; pp. 104 - 129
• Main Authors: Nguyen, Dieu D., Seth, Anil C., Neumayer, Nadine, Iguchi, Satoru, Cappellari, Michelle, Strader, Jay, Chomiuk, Laura, Tremou, Evangelia, Pacucci, Fabio, Nakanishi, Kouichiro, Bahramian, Arash, Nguyen, Phuong M., den Brok, Mark, Ahn, Christopher C., Voggel, Karina T., Kacharov, Nikolay, Tsukui, Takafumi, Ly, Cuc K., Dumont, Antoine, Pechetti, Renuka
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 10.02.2019; IOP Publishing
• Subjects: Accretion; Adaptive optics; Astrophysics; Black holes; Color; Deposition; Galactic nuclei; Galaxies; galaxies: individual (NGC 205, NGC 5102, and NGC 5206); galaxies: kinematics and dynamics; galaxies: nuclei; Hubble Space Telescope; Kinematics; Optics; quasars: supermassive black holes; Radio emission; Space telescopes; Spectroscopy; Star & galaxy formation; Star formation; Stars & galaxies; Stellar populations; Systematic errors
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aafe7a

We improve the dynamical black hole (BH) mass estimates in three nearby low-mass early-type galaxies: NGC 205, NGC 5102, and NGC 5206. We use new Hubble Space Telescope (HST)/STIS spectroscopy to fit the star formation histories of the nuclei in these galaxies, and use these measurements to create local color-mass-to-light ratio (M/L) relations. We then create new mass models from HST imaging and combined with adaptive optics kinematics, we use Jeans dynamical models to constrain their BH masses. The masses of the central BHs in NGC 5102 and NGC 5206 are both below one million solar masses and are consistent with our previous estimates, M and M (3 errors), respectively. However, for NGC 205, the improved models suggest the presence of a BH for the first time, with a best-fit mass of M (3 errors). This is the least massive central BH mass in a galaxy detected using any method. We discuss the possible systematic errors of this measurement in detail. Using this BH mass, the existing upper limits of both X-ray, and radio emissions in the nucleus of NGC 205 suggest an accretion rate 10−5 of the Eddington rate. We also discuss the color-M/Leff relations in our nuclei and find that the slopes of these vary significantly between nuclei. Nuclei with significant young stellar populations have steeper color-M/Leff relations than some previously published galaxy color-M/Leff relations.