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Full-Text Articles in Physical Sciences and Mathematics
A Cosmic Milestone: Constraints From Metal-Poor Halo Stars On The Cosmological Reionization Epoch, Aparna Venkatesan
A Cosmic Milestone: Constraints From Metal-Poor Halo Stars On The Cosmological Reionization Epoch, Aparna Venkatesan
Physics and Astronomy
Theoretical studies and current observations of the high-redshift intergalactic medium (IGM) indicate that at least two cosmic transitions occur by the time the universe reaches gas metallicities of about 10-3 Z☉. One is the cosmological reionization of the IGM, and the second is the transition from a primordial to present-day mode of star formation. We quantify this relation through new calculations of the ionizing radiation produced in association with the elements carbon, oxygen, and silicon observed in Galactic metal-poor halo stars, which are likely second-generation objects formed in the wake of primordial supernovae. We demonstrate that sufficient …
The Radiative Transport Of Dust In Primordial Galaxies And Second-Generation Star Formation, Aparna Venkatesan, Biman B. Nath, J Shull
The Radiative Transport Of Dust In Primordial Galaxies And Second-Generation Star Formation, Aparna Venkatesan, Biman B. Nath, J Shull
Physics and Astronomy
We investigate the radiativetransport of dust inprimordial galaxies in thepresence of the UVradiation field from thefirst metal-free stars. Wefind that dust createdin the first supernova(SN) explosions can bedriven through the interiorof the SN remnantto accumulate in theSN shells, where second-generationstars may form fromcompressed cooling gas. Thisscenario requires metal-free starsto form continuously overtimescales of up to10 Myr, consistent withrecent estimates. Silicate andgraphite grains, as wellas iron-bearing magnetites, aretransported to the shellsfor reasonable parameter assumptions,but their relative yieldsfrom primordial SNe isan important factor inthe resulting abundance ratios.We compare the resultsof segregated grain transportwith the current nucleosyntheticdata on extremely metal-poorGalactic halo stars. Fossilsignatures …