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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660602.0, MPI für Astronomie / Publikationen_mpia
A stellar dynamical mass measurement of the black hole in NGC 3998 from Keck adaptive optics observations
Authors:Walsh, Jonelle L.; van den Bosch, Remco C. E.; Barth, Aaron J.; Sarzi, Marc
Date of Publication (YYYY-MM-DD):2012
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Issue / Number:1
Start Page:id. 79
Review Status:not specified
Audience:Experts Only
Abstract / Description:We present a new stellar dynamical mass measurement of the black hole in the nearby, S0 galaxy NGC 3998. By combining laser guide star adaptive optics observations obtained with the OH-Suppressing Infrared Imaging Spectrograph on the Keck II telescope with long-slit spectroscopy from the Hubble Space Telescope and the Keck I telescope, we map out the stellar kinematics on both small spatial scales, well within the black hole sphere of influence, and large scales. We find that the galaxy is rapidly rotating and exhibits a sharp central peak in the velocity dispersion. Using the kinematics and the stellar luminosity density derived from imaging observations, we construct three-integral, orbit-based, triaxial stellar dynamical models. We find the black hole has a mass of M BH = (8.1+2.0 -1.9) × 108 M &sun;, with an I-band stellar mass-to-light ratio of M/L = 5.0+0.3 -0.4 M &sun;/L &sun; (3σ uncertainties), and that the intrinsic shape of the galaxy is very round, but oblate. With the work presented here, NGC 3998 is now one of a very small number of galaxies for which both stellar and gas dynamical modeling have been used to measure the mass of the black hole. The stellar dynamical mass is nearly a factor of four larger than the previous gas dynamical black hole mass measurement. Given that this cross-check has so far only been attempted on a few galaxies with mixed results, carrying out similar studies in other objects is essential for quantifying the magnitude and distribution of the cosmic scatter in the black hole mass-host galaxy relations.
Free Keywords:galaxies: active; galaxies: individual: NGC 3998; galaxies: kinematics and dynamics; galaxies: nuclei
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://cdsads.u-strasbg.fr/abs/2012ApJ...753...79W [ID No:1]
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