Experimental Results for H2 Formation from H− and H and Implications for First Star Formation
Kreckel H.; Bruhns H.; Čížek M.; Glover S. C. O.; Miller K. A.; Urbain X.; Savin D. W.
During the epoch of first star formation, molecular hydrogen (H2) generated via associative detachment
(AD) of H− and H is believed to have been the main coolant of primordial gas for temperatures below
104 kelvin. The uncertainty in the cross section for this reaction has limited our understanding of
protogalaxy formation during this epoch and of the characteristic masses and cooling times for the first
stars. We report precise energy-resolved measurements of the AD reaction, made with the use of a
specially constructed merged-beams apparatus. Our results agreed well with the most recent theoretically
calculated cross section, which we then used in cosmological simulations to demonstrate how the reduced
AD uncertainty improves constraints of the predicted masses for Population III stars.
| type: | article |
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| journal: | Science |
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| volume: | 329 |
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| nr: | 69 |
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| year: | 2010 |
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