The M87 Black Hole Mass from Gas-dynamical Models of Space Telescope Imaging Spectrograph Observations
Abstract
The supermassive black hole of M87 is one of the most massive black holes known and has been the subject of several stellar and gas-dynamical mass measurements; however, the most recent revision to the stellar-dynamical black hole mass measurement is a factor of about two larger than the previous gas-dynamical determinations. Here, we apply comprehensive gas-dynamical models that include the propagation of emission-line profiles through the telescope and spectrograph optics to new Space Telescope Imaging Spectrograph observations from the Hubble Space Telescope. Unlike the previous gas-dynamical studies of M87, we map out the complete kinematic structure of the emission-line disk within ~40 pc from the nucleus, and find that a small amount of velocity dispersion internal to the gas disk is required to match the observed line widths. We examine a scenario in which the intrinsic velocity dispersion provides dynamical support to the disk, and determine that the inferred black hole mass increases by only 6%. Incorporating this effect into the error budget, we ultimately measure a mass of M_{BH} = (3.5^{+0.9}_{-0.7}) \times 10^9\, M_\odot (68% confidence). Our gas-dynamical black hole mass continues to differ from the most recent stellar-dynamical mass by a factor of two, underscoring the need for carrying out more cross-checks between the two main black hole mass measurement methods.
Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-12162.- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2013
- DOI:
- 10.1088/0004-637X/770/2/86
- arXiv:
- arXiv:1304.7273
- Bibcode:
- 2013ApJ...770...86W
- Keywords:
-
- galaxies: active;
- galaxies: individual: M87 NGC 4486;
- galaxies: kinematics and dynamics;
- galaxies: nuclei;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 11 pages, 7 figures, accepted for publication in ApJ