The birth of intermediate-mass black holes in primordial galaxies

Muhammad A. Latif, Sadegh Khochfar, Dominik Schleicher, Daniel J. Whalen

Research output: Contribution to journalArticlepeer-review


The discovery of quasars at z ≳ 7 poses serious challenges because it is not known how109 M black holes formed by this epoch. The leading candidates for the seeds of these quasars are 105 M direct-collapse black holes forming in atomically cooled haloes at z ∼ 15 - 20. However, the Lyman-Werner (LW) UV backgrounds required to form such objects are extreme, ≳ 10J21, and may have been rare in the early universe. Here, we model the formation of Population III stars in moderate LW backgrounds of 100 and 500 J21 that were much more common at early times. We find that these backgrounds allow haloes to grow to a few 106- 107M and virial temperatures of nearly 104 K before collapsing but do not completely sterilize them of H2. At the onset of collapse, Lyα cooling dominates in the outer regions of the halo but H2 cooling regulates the collapse of the core, at rates that are 10 - 50 times those in minihaloes because of higher virial temperatures. Supercharged H2 cooling leads to the formation of 1800- 2800 M primordial stars, with radiative feedback from the star halting accretion and setting its upper limit in mass. Such stars may lead to a population of less-massive, lower luminosity quasars that could be discovered by the James Webb Space Telescope, Euclid and the Roman Space Telescope in the coming decade.
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Publication statusAccepted for publication - 16 Sept 2021


  • quasars: general
  • black hole physics
  • early universe
  • dark ages, reionization, first stars
  • galaxies: formation
  • galaxies: high-redshift


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