Is There a Black Hole in NGC 4382?
Abstract
We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the galaxy NGC 4382 (M85) and axisymmetric models of the galaxy to determine mass-to-light ratio (Upsilon V ) and central black hole mass (M BH). We find Upsilon V = 3.74 ± 0.1 M sun/L sun and M BH = 1.3+5.2 - 1.2 × 107 M sun at an assumed distance of 17.9 Mpc, consistent with no black hole. The upper limit, M BH < 9.6 × 107 M sun(2σ) or M BH < 1.4 × 108(3σ), is consistent with the current M-σ relation, which predicts M BH = 8.8 × 107 M sun at σ e = 182 km s-1, but low for the current M - L relation, which predicts M BH = 7.8 × 108 M sun at LV = 8.9 × 1010 L sun, V . HST images show the nucleus to be double, suggesting the presence of a nuclear eccentric stellar disk, analogous to the Tremaine disk in M31. This conclusion is supported by the HST velocity dispersion profile. Despite the presence of this non-axisymmetric feature and evidence of a recent merger, we conclude that the reliability of our black hole mass determination is not hindered. The inferred low black hole mass may explain the lack of nuclear activity.
Based on observations made with the 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 GO proposals 5999, 6587, 6633, 7468, and 9107.- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2011
- DOI:
- 10.1088/0004-637X/741/1/38
- arXiv:
- arXiv:1108.1808
- Bibcode:
- 2011ApJ...741...38G
- Keywords:
-
- black hole physics;
- galaxies: individual: NGC 4382 M85;
- galaxies: kinematics and dynamics;
- galaxies: nuclei;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 10 pages, 8 figures, accepted by ApJ