THE MEGAMASER COSMOLOGY PROJECT. III. ACCURATE MASSES OF SEVEN SUPERMASSIVE BLACK HOLES IN ACTIVE GALAXIES WITH CIRCUMNUCLEAR MEGAMASER DISKS

By C. Kuo, J. Braatz, Jim Condon, C. Impellizzeri, K. Lo, I. Zaw, M. Schenker, Christian Henkel, M. Reid, Jenny E. Greene. 2010

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Observations of H2O masers from circumnuclear disks in active galaxies for the Megamaser Cosmology Project (MCP) allow accurate measurement of the mass of supermassive black holes (BH) in these galaxies. We present the Very Long Baseline Interferometry images and kinematics of water maser emission in six active galaxies: NGC 1194, NGC 2273, NGC 2960 (Mrk 1419), NGC 4388, NGC 6264 and NGC 6323. We use the Keplerian rotation curves of these six megamaser galaxies, plus a seventh previously published, to determine accurate enclosed masses within the central ∼0.3 pc of these galaxies, smaller than the radius of the sphere of influence of the central mass in all cases. We also set lower limits to the central mass densities of between 0.12 × 1010 and 61 × 1010 M☉ pc−3. For six of the seven disks, the high central densities rule out clusters of stars or stellar remnants as the central objects, and this result further supports our assumption that the enclosed mass can be attributed predominantly to a supermassive BH. The seven BHs have masses ranging between 0.75 × 107 and 6.5 × 107 M☉, with the mass errors dominated by the uncertainty of the Hubble constant. We compare the megamaser BH mass determination with BH mass measured from the virial estimation method. The virial estimation BH mass in four galaxies is consistent with the megamaser BH mass, but the virial mass uncertainty is much greater. Circumnuclear megamaser disks allow the best mass determination of the central BH mass in external galaxies and significantly improve the observational basis at the low-mass end of the M–σ⋆ relation. The M–σ⋆ relation may not be a single, low-scatter power law as originally proposed. MCP observations continue and we expect to obtain more maser BH masses in the future.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2aecc28dfee73225698051504130f5a3b81fac17

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Citations in the corpus

Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies (2013, methodology): “NGC 2960: The BH discovery paper is Henkel et al. (2002); a reliable BH mass was determined by Kuo et al. (2011).”
Doing Science with eLISA: Astrophysics and Cosmology in the Millihertz Regime (2012, background): “…in low mass spiral galaxies and dwarfs with and without a bulge (Barth et al., 2004, Greene and Ho, 2004, Greene et al., 2008, Jiang et al., 2011a,b, Kuo et al., 2011, Xiao et al., 2011) and evidence exists that some of these low mass black holes of M 105 M cohabit nuclear star clusters (Barth…”
Stellar Dynamics and Stellar Phenomena Near a Massive Black Hole (2017, background): “Circumnuclear maser disks are typically found around MBHs with M• ∼ 107 M and display warps of a few degrees (Kuo et al. 2011).”
REVISITING THE SCALING RELATIONS OF BLACK HOLE MASSES AND HOST GALAXY PROPERTIES (2012, methodology): “…(6 = Verolme et al. 2002) ; (7 = Bender et al. 2005) ; (8 = Krajnović et al. 2009) ; (9 = Schulze & Gebhardt 2011) ; (10 = Bower et al. 2001) ; (11 = Kuo et al. 2011) ; (12 = Atkinson et al. 2005) ; (13 = Nowak et al. 2008) ; (14 = Rusli et al. 2011) ; (15 = Rusli 2012) ; (16 = Gebhardt et al.…”
The Megamaser Cosmology Project. XIII. Combined Hubble Constant Constraints (2020, methodology): “NGC 6264 A VLBI map for the maser system in NGC 6264 was first presented in Kuo et al. (2011), and Kuo et al. 2 Disk maser spectra are typically characterized by three groups of maser features arranged roughly symmetrically about the systemic velocity of the galaxy (see, e.g., Nakai et al. 1993;…”