2010/07/16 by Jenny E. Greene, J. E. Greene, C. Y. Peng +12 · 257 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics #Black hole (networking) #Bulge #Elliptical galaxy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Galaxy rotation curve #Megamaser #Milky Way #Physics #Star formation #Stellar kinematics #Stellar mass #Velocity dispersion #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/721/1/26
published in The Astrophysical Journal 721(1), 26-45 (IOP Publishing) · 21 pages, 14 figures, accepted for publication in the Astrophysical Journal
arxiv created 2010/07/16 · openalex publication_date 2010/08/26 · arxiv updated 2015/05/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/08
The black hole (BH)–bulge correlations have greatly influenced the last decade of efforts to understand galaxy evolution. Current knowledge of these correlations is limited predominantly to high BH masses ( M BH ≳10 8 M ☉ ) that can be measured using direct stellar, gas, and maser kinematics. These objects, however, do not represent the demographics of more typical L < L * galaxies. This study transcends prior limitations to probe BHs that are an order of magnitude lower in mass, using BH mass measurements derived from the dynamics of H 2 O megamasers in circumnuclear disks. The masers trace the Keplerian rotation of circumnuclear molecular disks starting at radii of a few tenths of a pc from the central BH. Modeling of the rotation curves, presented by Kuo et al., yields BH masses with exquisite precision. We present stellar velocity dispersion measurements for a sample of nine megamaser disk galaxies based on long-slit observations using the B&C spectrograph on the Dupont telescope and the Dual Imaging Spectrograph on the 3.5 m telescope at Apache Point. We also perform bulge-to-disk decomposition of a subset of five of these galaxies with Sloan Digital Sky Survey imaging. The maser galaxies as a group fall below the M BH –σ * relation defined by elliptical galaxies. We show, now with very precise BH mass measurements, that the low-scatter power-law relation between M BH and σ * seen in elliptical galaxies is not universal. The elliptical galaxy M BH –σ * relation cannot be used to derive the BH mass function at low mass or the zero point for active BH masses. The processes (perhaps BH self-regulation or minor merging) that operate at higher mass have not effectively established an M BH –σ * relation in this low-mass regime.