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titleAbsorption Measurement of Hydrogen Molecules in the Early Universe
Author(eng)Hiroshi, SHIBAI
Author Affiliation(eng)Nagoya University, Graduate School of Science
Issue Date2000-12
PublisherInstitute of Space and Astronautical Science
Publication titleThe Institute of Space and Astronautical Science repot. S.P.
Start page69
End page74
Publication date2000-12
AbstractThe observability of Hydrogen molecules in absorption is investigated. For solarabundances, such as in the Galaxy, the absorption measurement is very difficult because the ab-sorption efficiency of the Hydrogen molecular absorption lines is significantly smaller than that ofdust grains. On the other hand, in the metal-poor condition as expected in the early Universe,the absorption efficiency of the Hydrogen molecules become comparable with or larger than thatof the dust grains. If we could use bright infrared sources behind the molecular gas clouds, theabsorption measurement of the Hydrogen molecules would be an important technique to analyzethe primordial gas clouds that are contracting into first-generation objects. The SPICA (SpaceInfrared Telescope for Cosmology and Astrophysics) will be sensitive enough to detect a moleculargas could of 1024 cm-2 against an infrared source of 10 mJy flux. These observations would beable to reveal the distribution of the primordial molecular gas clouds in the early Universe.
Document TypeDepartmental Bulletin Paper
JAXA Category宇宙科学研究所

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