The formation of pregalactic objects from white-noise density perturbations

Robert J. Scherrer, Tanmay Vachaspati

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We investigate the general case of baryonic collapse in a universe dominated by cold dark matter with a white-noise fluctuation spectrum δρ/ρ = (M/M0)-1/2. For Ω = 1 and Ωbh2 = 0.02, baryonic collapse from molecular cooling requires a minimum fluctuation mass of M0 = 0.12h-4.4 M ; below this mass, baryons can collapse out of the Hubble flow and virialize, but the formation of compact objects is impossible. This requirement produces a minimum redshift for the formation of pregalactic objects from white-noise perturbations: 1 + z > 16. The minimum baryonic mass which can cool and collapse into bound objects is M = 4000 M h-2.4. As a specific example, we examine white-noise fluctuations in the axion field.

Original languageEnglish (US)
Pages (from-to)338-342
Number of pages5
JournalAstrophysical Journal
Issue number2
StatePublished - Oct 1 1990
Externally publishedYes


  • Cosmology
  • Elementary particles

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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