Primordial Molecular Emission in Population III Galaxies

Abstract

We study formation of molecules in primordial prestellar clumps and evaluate the line luminosities to assess detectability by next-generation facilities. If the initial H_2 fraction is sufficiently high, HD becomes an important coolant in the clumps. The luminosity from such HD cooling clumps is lower than that from H_2 cooling ones because of 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 + H_2. LiH does not become an important coolant in any density range. The luminous emission lines from the prestellar cores include H_2 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 H_2 emission in a large pre-galactic cloud that forms metal-free stars at a high rate of \sim 10^3 M_s/yr at redshift z<10. We also derive an analytical expression for the luminosity that reproduces the numerical results.

32 pages, 13 figures, 3 tables, accepted PASJ

References in corpus (7)

• Thermal and Fragmentation Properties of Star-forming Clouds in Low-metallicity Environments
• A Subaru Search for Ly-alpha Blobs in and around the Proto-cluster Region at Redshift z=3.1
• Detecting Population III stars through observations of near-IR cosmic infrared background anisotropies
• The Nature of Lya Blobs: Supernova-Dominated Primordial Galaxies
• Embedded Star Clusters in the W51 Giant Molecular Cloud
• Observing H2 Emission in Forming Galaxies
• H_2 Line Emission Associated with the Formation of the First Stars

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• The Dawn of Chemistry
• Molecules in galaxies
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• The First Stars
• Origins Space Telescope Mission Concept Study Report
• Galaxy evolution studies with the SPace IR telescope for Cosmology and Astrophysics (SPICA): the power of IR spectroscopy
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• ROBO: a Model and a Code for the Study of the Interstellar Medium
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• Global radiation signature from early structure formation
• Probing the High-Redshift Universe with SPICA: Toward the Epoch of Reionization and Beyond
• Effect of lithium hydride on the cooling of primordial gas
• The first molecules in the intergalactic medium and halos of the Dark Ages and Cosmic Dawn
• Hydrogen Molecules in the Dark Ages Halos: Thermal Emission vs. Resonant Scattering
• The Minimum Stellar Mass in Early Galaxies
• Open questions in the study of population III star formation
• The Effects of Dark Matter Annihilation and Dark Matter-Baryon Velocity Offsets at Cosmic Dawn
• Sensitivity of the redshifted 21 cm signal from the Dark Ages to parameters of primordial magnetic fields