The Low-mass, Highly Accreting Black Hole Associated with the Active Galactic Nucleus 2XMM J123103.2+110648
Abstract
Optical spectra and images taken with the Baade 6.5 m Magellan telescope confirm that 2XMM J123103.2+110648, a highly variable X-ray source with an unusually soft spectrum, is indeed associated with a type 2 (narrow-line) active nucleus at a redshift of z = 0.11871. The absence of broad Hα or Hβ emission in an otherwise X-ray unabsorbed source suggests that it intrinsically lacks a broad-line region. If, as in other active galaxies, the ionized gas and stars in J1231+1106 are in approximate virial equilibrium, and the M BH - σ* relation holds, the exceptionally small velocity dispersion of σ = 33.5 km s-1 for [O III] λ5007 implies that M BH ≈ 105 M ⊙, among the lowest ever detected. Such a low black hole mass is consistent with the general characteristics of the host, a small, low-luminosity, low-mass disk galaxy. We estimate the Eddington ratio of the black hole to be gsim0.5, in good agreement with expectations based on the X-ray properties of the source.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2012
- DOI:
- 10.1088/2041-8205/759/1/L16
- arXiv:
- arXiv:1210.0440
- Bibcode:
- 2012ApJ...759L..16H
- Keywords:
-
- black hole physics;
- galaxies: active;
- galaxies: nuclei;
- galaxies: Seyfert;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- To appear in The Astrophysical Journal Letters