Book contents
- Frontmatter
- Contents
- Preface
- Conference participants
- Conference photograph / poster
- 1 Physics of H2 and HD
- 2 Formation - Destruction
- 3 Observations and Models
- 4 Extragalactic and Cosmology
- The Role of H2 Molecules in Cosmological Structure Formation
- The Role of H2 Molecules in Primordial Star Formation
- Evolution of Primordial H2 for Different Cosmological Models
- Dynamics of H2 Cool Fronts in the Primordial Gas
- Is Reionization Regulated by H2 in the Early Universe?
- H2 in Galaxies
- Transformation of Galaxies within the Hubble Sequence
- Extragalactic H2 and its Variable Relation to CO
- The Galactic Dark Matter Halo: Is it H2?
- Observations of H2 in Quasar Absorbers
- H2 Emission as a Diagnostic of Physical Processes in Starforming Galaxies
- 5 Outlook
- Author index
The Role of H2 Molecules in Primordial Star Formation
from 4 - Extragalactic and Cosmology
Published online by Cambridge University Press: 04 August 2010
- Frontmatter
- Contents
- Preface
- Conference participants
- Conference photograph / poster
- 1 Physics of H2 and HD
- 2 Formation - Destruction
- 3 Observations and Models
- 4 Extragalactic and Cosmology
- The Role of H2 Molecules in Cosmological Structure Formation
- The Role of H2 Molecules in Primordial Star Formation
- Evolution of Primordial H2 for Different Cosmological Models
- Dynamics of H2 Cool Fronts in the Primordial Gas
- Is Reionization Regulated by H2 in the Early Universe?
- H2 in Galaxies
- Transformation of Galaxies within the Hubble Sequence
- Extragalactic H2 and its Variable Relation to CO
- The Galactic Dark Matter Halo: Is it H2?
- Observations of H2 in Quasar Absorbers
- H2 Emission as a Diagnostic of Physical Processes in Starforming Galaxies
- 5 Outlook
- Author index
Summary
H2 and HD molecules provide the cooling needed for the fragmentation and collapse of the first structures in the universe. In this review, we describe the main chemical and physical processes occurring in the primordial gas after the recombination epoch. We also highlight the areas where improvements in the determination of reaction rates and excitation coefficients are necessary to reduce the remaining uncertainties in the predictions of the numerical models. The interaction of primordial molecules with the CBR and the role of H2 and HD cooling in the early universe are discussed. Finally, we comment on the results of recent simulations of the fragmentation and collapse of primordial clouds, with an emphasis on the typical mass scale of the first objects.
Introduction
The formation of the first stellar objects in the universe is a fascinating, yet little understood process. Although we have now observational data on bright quasars and galaxies out to redshifts of about 5 (corresponding to 109 yr after the Big Bang) and on the density fluctuations at redshifts about 1000 (or an age of ∼ 106 yr), there is no direct evidence as to when and how the first structures formed. This unique epoch and the nature of the primordial objects define what has been called the end of the “Dark Ages” (Rees 1999).
According to Big Bang cosmology, there must have been an epoch in the history of the universe during which the original gas mixture was altered by the manufacture of heavy elements inside stars.
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- Molecular Hydrogen in Space , pp. 247 - 258Publisher: Cambridge University PressPrint publication year: 2000