Cosmological production of H_2 before the formation of the first galaxies

Abstract

Previous calculations of the pregalactic chemistry have found that a small amount of H_2, x[H_2]=n[H_2]/n[H] = 2.6e-6, is produced catalytically through the H^-, H_2^+, and HeH^+ mechanisms. We revisit this standard calculation taking into account the effects of the nonthermal radiation background produced by cosmic hydrogen recombination, which is particularly effective at destroying H^- via photodetachment. We also take into consideration the non-equilibrium level populations of H_2^+, which occur since transitions among the rotational-vibrational levels are slow compared to photodissociation. The new calculation predicts a final H_2 abundance of x[H_2] = 6e-7 for the standard cosmology. This production is due almost entirely to the H^- mechanism, with ~1 per cent coming from HeH^+ and ~0.004 per cent from H_2^+. We evaluate the heating of the diffuse pregalactic gas from the chemical reactions that produce H_2 and from rotational transitions in H_2, and find them to be negligible.

arXiv comment13 pages, 5 figures, MNRAS submitted

References in corpus (17)

• Cosmological parameter analysis including SDSS Ly-alpha forest and galaxy bias: constraints on the primordial spectrum of fluctuations, neutrino mass, and dark energy
• Wilkinson Microwave Anisotropy Probe (WMAP) First Year Observations: TE Polarization
• How small were the first cosmological objects?
• A measurement by BOOMERANG of multiple peaks in the angular power spectrum of the cosmic microwave background
• DASI First Results: A Measurement of the Cosmic Microwave Background Angular Power Spectrum
• A New Calculation of the Recombination Epoch
• How exactly did the Universe become neutral?
• A High Spatial Resolution Analysis of the MAXIMA-1 Cosmic Microwave Background Anisotropy Data
• Cosmological Formation of Low-Mass Objects
• Measuring the Small-Scale Power Spectrum of Cosmic Density Fluctuations Through 21 cm Tomography Prior to the Epoch of Structure Formation
• H_2 Cooling of Primordial Gas Triggered by UV Irradiation
• The Sensitivity of First Generation Epoch of Reionization Observatories and Their Potential for Differentiating Theoretical Power Spectra
• Cosmological Implications of the Uncertainty in H- Destruction Rate Coefficients
• Calculated spectra for HeH+ and its effect on the opacity of cool metal poor stars
• Spectral distortions to the Cosmic Microwave Background from the recombination of hydrogen and helium
• Ionizing radiation from hydrogen recombination strongly suppresses the lithium scattering signature in the CMB
• Cosmological Recombination of Lithium and its Effect on the Microwave Background Anisotropies

Cited by in corpus (42)

• Atomic Dark Matter
• Early Cosmological HII/HeIII Regions and Their Impact on Second-Generation Star Formation
• The Dawn of Chemistry
• Metal Cooling in Simulations of Cosmic Structure Formation
• The first generation of stars in LCDM cosmology
• Twin Higgs Asymmetric Dark Matter
• The formation of direct collapse black holes under the influence of streaming velocities
• The Influence of Streaming Velocities on the Formation of the First Stars
• Molecules in galaxies
• Effects of primordial chemistry on the cosmic microwave background
• Vibrational level population of H${}_2$ and H${}_2^{+}$ in the early Universe
• Radiative cooling functions for primordial molecules
• The role of HD cooling in primordial star formation
• Primordial magnetic fields and formation of molecular hydrogen
• Primordial helium recombination III: Thomson scattering, isotope shifts, and cumulative results
• The Habitable Epoch of the Early Universe
• Feedback from the IR Background in the Early Universe
• Cosmic rays and the primordial gas
• Non-thermal photons and H2 formation in the early Universe
• Early structure formation from primordial density fluctuations with a blue-tilted power spectrum
• Observation and calculation of the quasi-bound rovibrational levels of the electronic ground state of H${}_2^{+}$
• Role of the H${}_2^{+}$ channel in the primordial star formation under strong radiation field and the critical intensity for the supermassive star formation
• Chemistry of heavy elements in the Dark Ages
• Constraining galactic structures of mirror dark matter
• Non-equilibrium H${}_2$ formation in the early Universe: energy exchanges, rate coefficients and spectral distortions
• Molecular Chemistry for Dark Matter II: Recombination, Molecule Formation, and Halo Mass Function in Atomic Dark Matter
• State resolved data for radiative association of H and p and for photodissociation of H${}_2^{+}$
• Molecular fluorine chemistry in the early Universe
• Molecular hydrogen in the cosmic recombination epoch
• Triggering the formation of direct collapse black holes by their congeners
• Feeding plankton to whales: high-redshift supermassive black holes from tiny black hole explosions
• Thermal and Resonant Emission of Dark Ages Halos in the Rotational Lines of HeH${}^{+}$
• Molecules in the early Universe
• Halos in Dark Ages: formation and chemistry
• Effects of dust grain size distribution on the abundances of CO and H${}_2$ in galaxy evolution
• The Chemistry of the Early Universe
• Light one-electron quasi-molecular ions within the finite-basis-set method for the two-center Dirac equation
• Non-thermal photons and direct photodissociation of H2, HD and HeH+ in the chemistry of the primordial Universe
• Zero Metallicity with Zero CPU Hours: Masses of the First Stars on the Laptop
• Direct Collapse Black Hole Candidates from Decaying Dark Matter
• The first stars
• On the Habitability of Our Universe