Primordial molecular emission in population III galaxies

Hiromi Mizusawa, Kazuyuki Omukai, Ryoichi Nishi

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


We consider the formation of molecules in primordial prestellar clumps and evaluate the line luminosities to assess detectability by next-generation observational facilities. If the initial H2 fraction is sufficiently high, HD becomes an important coolant in the clumps. The luminosity from such HD cooling clumps is lower than that from H2 cooling ones because of the lower temperature (< 100K). As for Li reactions, we include the three-body LiH formation approximately. The Li molecular fraction remains very low (< 10-3) throughout the evolution, owing to the high dissociative reaction rate of LiH + H → Li + H2. LiH does not become an important coolant in any density range. The luminous emission lines from the prestellar cores include H2 rovibrational lines [1-0 Q(1), 1-0 O(3), 1-0 O(5)] and pure rotational lines [0-0 S(3), 0-0 S(4), 0-0 S(5)]. The next-generation facilities SPICA and JWST are able to detect H2 emission in a large pre-galactic cloud that forms metal-free stars at a high rate of ∼ 103 M yr-1 at a redshift of z < 10. We also derive an analytical expression for the luminosity that reproduces the numerical results.

Original languageEnglish
Pages (from-to)951-967
Number of pages17
JournalPublications of the Astronomical Society of Japan
Issue number6
Publication statusPublished - 2005
Externally publishedYes


  • Cosmology: early universe
  • Galaxies: high-redshift
  • Infrared: galaxies
  • Molecular processes
  • Stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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