Wandering of the central black hole in a galactic nucleus and correlation of the black hole mass with the bulge mass

Abstract

We investigate a mechanism for a super-massive black hole at the center of a galaxy to wander in the nucleus region. A situation is supposed in which the central black hole tends to move by the gravitational attractions from the nearby molecular clouds in a nuclear bulge but is braked via the dynamical frictions by the ambient stars there. We estimate the approximate kinetic energy of the black hole in an equilibrium between the energy gain rate through the gravitational attractions and the energy loss rate through the dynamical frictions, in a nuclear bulge composed of a nuclear stellar disk and a nuclear stellar cluster as observed from our Galaxy. The wandering distance of the black hole in the gravitational potential of the nuclear bulge is evaluated to get as large as several 10 pc, when the black hole mass is relatively small. The distance, however, shrinks as the black hole mass increases and the equilibrium solution between the energy gain and loss disappears when the black hole mass exceeds an upper limit. As a result, we can expect the following scenario for the evolution of the black hole mass: When the black hole mass is smaller than the upper limit, mass accretion of the interstellar matter in the circum-nuclear region, causing the AGN activities, makes the black hole mass larger. However, when the mass gets to the upper limit, the black hole loses the balancing force against the dynamical friction and starts spiraling downward to the gravity center. From simple parameter scaling, the upper mass limit of the black hole is found to be proportional to the bulge mass and this could explain the observed correlation of the black hole mass with the bulge mass.

References in corpus (14)

• A Fundamental Relation Between Supermassive Black Holes and Their Host Galaxies
• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
• A Relationship Between Nuclear Black Hole Mass and Galaxy Velocity Dispersion
• Observational Evidence of AGN Feedback
• The Relation between Black Hole Mass, Bulge Mass, and Near-Infrared Luminosity
• The Co-Evolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe
• What Drives the Growth of Black Holes?
• The Nuclear Bulge of the Galaxy. III. Large-Scale Physical Characteristics of Stars and Interstellar Matter
• A Fundamental Relation Between Compact Stellar Nuclei, Supermassive Black Holes, and Their Host Galaxies
• Black Hole Demographics from the M(BH)-sigma Relation
• The Mass Spectra of Giant Molecular Clouds in the Local Group
• Cold gas properties of the Herschel Reference Survey. II. Molecular and total gas scaling relations
• ALMA observations of molecular tori around massive black holes
• The Fueling and Evolution of AGN: Internal and External Triggers

Cited by in corpus (1)

• Accretion environments of active galactic nuclei