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The most metal-poor damped Lyα systems: An insight into dwarf galaxies at high redshift

Cooke, R.J.; Pettini, M.; Jorgenson, R.A.

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Authors

M. Pettini

R.A. Jorgenson



Abstract

In this paper we analyze the kinematics, chemistry, and physical properties of a sample of the most metal-poor damped Lyα systems (DLAs), to uncover their links to modern-day galaxies. We present evidence that the DLA population as a whole exhibits a "knee" in the relative abundances of the α-capture and Fe-peak elements when the metallicity is [Fe/H] sime –2.0, assuming that Zn traces the buildup of Fe-peak elements. In this respect, the chemical evolution of DLAs is clearly different from that experienced by Milky Way halo stars, but resembles that of dwarf spheroidal galaxies in the Local Group. We also find a close correspondence between the kinematics of Local Group dwarf galaxies and of high-redshift metal-poor DLAs, which further strengthens this connection. On the basis of such similarities, we propose that the most metal-poor DLAs provide us with a unique opportunity to directly study the dwarf galaxy population more than ten billion years in the past, at a time when many dwarf galaxies were forming the bulk of their stars. To this end, we have measured some of the key physical properties of the DLA gas, including their neutral gas mass, size, kinetic temperature, density, and turbulence. We find that metal-poor DLAs contain a warm neutral medium with T gas sime 9600 K predominantly held up by thermal pressure. Furthermore, all of the DLAs in our sample exhibit a subsonic turbulent Mach number, implying that the gas distribution is largely smooth. These results are among the first empirical descriptions of the environments where the first few generations of stars may have formed in the universe.

Citation

Cooke, R., Pettini, M., & Jorgenson, R. (2015). The most metal-poor damped Lyα systems: An insight into dwarf galaxies at high redshift. Astrophysical Journal, 800(1), Article 12. https://doi.org/10.1088/0004-637x/800/1/12

Journal Article Type Article
Publication Date Feb 1, 2015
Deposit Date Feb 20, 2017
Publicly Available Date Mar 29, 2024
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 800
Issue 1
Article Number 12
DOI https://doi.org/10.1088/0004-637x/800/1/12
Related Public URLs https://arxiv.org/abs/1406.7003

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Copyright Statement
© 2015. The American Astronomical Society. All rights reserved.





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