The cooling of shock-compressed primordial gas

2005/05/31 by Jarrett L. Johnson, Volker Bromm · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Cosmic microwave background #Cosmology and Gravitation Theories #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Radiative cooling #Redshift #Stars #astro-ph

paper · pdf · doi:10.1111/j.1365-2966.2005.09846.x

published as Mon.Not.Roy.Astron.Soc.366:247-256,2006 · 10 pages, 10 figures, accepted for publication in MNRAS with minor revisions, new table added

arxiv created 2005/11/10 · openalex publication_date 2006/01/09 · arxiv updated 2014/10/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We find that at redshifts z > 10, HD line cooling allows strongly-shocked primordial gas to cool to the temperature of the cosmic microwave background (CMB). This temperature is the minimum value attainable via radiative cooling. Provided that the abundance of HD, normalized to the total number density, exceeds a critical level of ~ 10^-8, the CMB temperature floor is reached in a time which is short compared to the Hubble time. We estimate the characteristic masses of stars formed out of shocked primordial gas in the wake of the first supernovae, and resulting from the mergers of dark matter haloes during hierarchical structure formation to be ~ 10 M_solar. In addition, we show that cooling by HD enables the primordial gas in relic H II regions to cool to temperatures considerably lower than those reached via H₂ cooling alone. We confirm that HD cooling is unimportant in cases where the primordial gas does not go through an ionized phase, as in the formation process of the very first stars in z ~ 20 minihaloes of mass ~ 10⁶ M_solar.

Citations

• The First Supernova Explosions in the Universe
• The formation of globular clusters in merging and interacting galaxies
• Induced formation of primordial low-mass stars
• Massive star formation in 100,000 years from turbulent and pressurized molecular clouds
• Nucleosynthetic signatures of the first stars
• Infrared Space ObservatorySpectra of R Coronae Borealis Stars. I. Emission Features in the Interval 3–25 Microns
• The Formation of the First Stars. I. The Primordial Star‐forming Cloud
• Accretion onto a primordial protostar
• In the Beginning: The First Sources of Light and the Reionization of the Universe
• The characteristic stellar mass as a function of redshift

Cited by

• Enhanced direct collapse due to Lyman α feedback
• The Impact of HD Cooling on the Formation of the First Stars