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Dwarf galaxies and the black hole scaling relations

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journal contribution
posted on 03.03.2021, 11:37 by A King, R Nealon
The sample of dwarf galaxies with measured central black hole masses M and velocity dispersions σ has recently doubled, and gives a close fit to the extrapolation of the M-σ relation for more massive galaxies. We argue that this is difficult to reconcile with suggestions that the scaling relations between galaxies and their central black holes are simply a statistical consequence of assembly through repeated mergers. This predicts black hole masses significantly larger than those observed in dwarf galaxies unless the initial distribution of uncorrelated seed black hole and stellar masses is confined to much smaller masses than earlier assumed. It also predicts a noticeable flattening of the M-σ relation for dwarfs, to M σ2 compared with the observed M σ4. In contrast black hole feedback predicts that black hole masses tend towards a universal M σ4 relation in all galaxies, and correctly gives the properties of powerful outflows recently observed in dwarf galaxies. These considerations emphasize once again that the fundamental physical black hole-galaxy scaling relation is between M and σ. The relation of M to the bulge mass Mb is acausal, and depends on the quite independent connection between Mb and σ set by stellar feedback.

History

Citation

Monthly Notices of the Royal Astronomical Society: Letters, Volume 502, Issue 1, March 2021, Pages L1–L5, https://doi.org/10.1093/mnrasl/slaa200

Author affiliation

Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society: Letters

Volume

502

Issue

1

Pagination

L1 - L5

Publisher

Oxford University Press (OUP)

issn

1745-3925

eissn

1745-3933

Acceptance date

08/12/2020

Copyright date

2020

Available date

16/12/2020

Language

en