The Onset of the Cold H i Phase in Disks of Protogalaxies
1995; IOP Publishing; Volume: 450; Linguagem: Inglês
10.1086/176116
ISSN1538-4357
Autores Tópico(s)Superconducting and THz Device Technology
Resumoview Abstract Citations (7) References (58) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Onset of the Cold H i Phase in Disks of Protogalaxies Corbelli, Edvige ; Salpeter, Edwin E. Abstract We discuss a possible delay experienced by protogalaxies with low gas column densities in forming stars over large scales. After the hydrogen has recombined, as the external ionizing UV flux decreases and the metal abundance Z increases, the H I, initially in the warm phase (T ≳ 5000 K), makes a transition to the cool phase (T ≲ 100 K). The minimum abundance Zmin for which this phase transition takes place in a small fraction of the Hubble time decreases rapidly with increasing gas column density. Therefore, in "anemic" disk galaxies where NH I is up to 10 times smaller than for normal large spirals, the onset of the cool H I phase is delayed. The onset of gravitational instability is also delayed since these objects are more likely to be gravitationally stable in the warm phase than progenitors of today's large spiral galaxies. The first substantial burst of star formation may occur only as late as redshift z ∼ 0.5 and may give a temporary high peak luminosity, possibly related to the "faint blue objects." Galaxy disks of lower column density tend to have lower escape velocities and a starburst/galactic fountain instability that decreases the gas content of the inner disk drastically. Publication: The Astrophysical Journal Pub Date: September 1995 DOI: 10.1086/176116 arXiv: arXiv:astro-ph/9503079 Bibcode: 1995ApJ...450...32C Keywords: GALAXIES: EVOLUTION; GALAXIES: FORMATION; GALAXIES: ISM; STARS: FORMATION; Astrophysics E-Print: TeX file, 24 pages, 4 figures available upon request from edvige@arcetri.astro.it, to appear in The Astrophysical J. (Sept. 1) full text sources arXiv | ADS |
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