How black holes stop their host galaxy from growing without AGN feedback

Daniel S. Eastwood*, Sadegh Khochfar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Supermassive black holes (SMBHs) withM• ~ 109 M atz > 6 likely originate from massive seed black holes (BHs). We investigate the consequences of seeding SMBHs with direct collapse BHs (DCBHs) (M• = 104-6M) on proto-galactic disc growth. We show that even in the absence of direct feedback effects, the growth of seed BHs reduces the development of gravitational instabilities in host galaxy discs, suppressing star formation and confining stars to a narrow ring in the disc and leading to galaxies at z ~6 which lie above the local BH-stellar mass relation. The relative magnitude of cosmic and BH accretion rates governs the evolution of the BH-stellar mass relation. For typical DCBH formation epochs, zi ~ 10, we find that star formation is inhibited in haloes growing at the average rate predicted by Λcold dark matter that host BHs capable of reaching M• ~ 109M by z ≳ 6. Slower growing BHs cause a delay in the onset of star formation; anM• ~ 106 M seed growing at 0.25 times the Eddington limit will delay star formation by ~100 Myr. This delay is reduced by a factor of ~10 if the halo growth rate is increased by ~0.6 σ. Our results suggest that SMBHs seeded by DCBHs and their host galaxies form in separate progenitor haloes. In the absence of subsequent mergers, higher than average cosmic accretion or earlier seed formation (zi ~ 20) are required to place the evolving BH on the local BH-stellar mass relation by z = 6.

Original languageEnglish
Pages (from-to)5673-5688
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date18 Aug 2018
Publication statusPublished - 1 Nov 2018


  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift


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