Black Hole Growth in Disk Galaxies Mediated by the Secular Evolution of Short Bars
- Key Laboratory of Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)
- Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)
- Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
- Max-Planck-Insitut für extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany)
The growth of black holes (BHs) in disk galaxies lacking classical bulges, which implies an absence of significant mergers, appears to be driven by secular processes. Short bars of sub-kiloparsec radius have been hypothesized to be an important mechanism for driving gas inflows to small scale, feeding central BHs. In order to quantify the maximum BH mass allowed by this mechanism, we examine the robustness of short bars to the dynamical influence of BHs. Large-scale bars are expected to be robust, long-lived structures; extremely massive BHs, which are rare, are needed to completely destroy such bars. However, we find that short bars, which are generally embedded in large-scale outer bars, can be destroyed quickly when BHs of mass M{sub bh}∼0.05%--0.2% of the total stellar mass (M{sub ⋆}) are present. In agreement with this prediction, all galaxies observed to host short bars have BHs with a mass fraction less than 0.2% M{sub ⋆}. Thus, the dissolution of short inner bars is possible, perhaps even frequent, in the universe. An important implication of this result is that inner-bar-driven gas inflows may be terminated when BHs grow to ∼0.1% M{sub ⋆}. We predict that 0.2% M{sub ⋆} is the maximum mass of BHs allowed if they are fed predominately via inner bars. This value matches well the maximum ratio of BH-to-host-galaxy stellar mass observed in galaxies with pseudo-bulges and most nearby active galactic nucleus host galaxies. This hypothesis provides a novel explanation for the lower M{sub bh}/M{sub ⋆} in galaxies that have avoided significant mergers compared with galaxies with classical bulges.
- OSTI ID:
- 22872580
- Journal Information:
- Astrophysical Journal Letters, Vol. 844, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United Kingdom
- Language:
- English
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