The small scatter in BH-host correlations and the case for self-regulated BH growth
Abstract
Supermassive black holes (BHs) obey tight scaling relations between their mass and host galaxy properties such as total stellar mass, velocity dispersion and potential well depth. This has led to the development of self-regulated models for BH growth, in which feedback from the central BH halts its own growth upon reaching a critical threshold. However, models have also been proposed in which feedback plays no role: so long as a fixed fraction of the host gas supply is accreted, relations like those observed can be reproduced. Here, we argue that the scatter in the observed BH–host correlations presents a demanding constraint on any model for these correlations, and that it favours self-regulated models of BH growth. We show that the scatter in the stellar mass fraction within a radius R in observed ellipticals and spheroids increases strongly at small R. At a fixed total stellar mass (or host velocity dispersion), on very small scales near the BH radius of influence, there is an order-of-magnitude scatter in the amount of gas that must have entered and formed stars. In short, the BH appears to 'know more' about the global host galaxy potential on large scales than the stars and gas supply on small scales. This is predicted in self-regulated models; however, models where there is no feedback would generically predict order-of-magnitude scatter in the BH–host correlations. Likewise, models in which the BH feedback in the 'bright' mode does not regulate the growth of the BH itself, but sets the stellar mass of the galaxy by inducing star formation or blowing out a mass in gas much larger than the galaxy stellar mass, are difficult to reconcile with the scatter on small scales.
Additional Information
© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 May 22. Received 2009 May 20; in original form 2009 March 17. We thank Eliot Quataert, Carlos Frenk and Lars Hernquist for helpful discussions. We also appreciate the hospitality of the Aspen Center for Physics, where this paper was partially developed. Support for PFH was provided by the Miller Institute for Basic Research in Science, University of California Berkeley.Attached Files
Published - mnras0398-0303.pdf
Accepted Version - 0903.3949.pdf
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Additional details
- Eprint ID
- 103544
- Resolver ID
- CaltechAUTHORS:20200529-093431825
- Miller Institute for Basic Research in Science
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2020-06-01Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field