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Effects of reionization on dwarf galaxy formation

Published online by Cambridge University Press:  01 June 2008

Massimo Ricotti
Massimo Ricotti*
Affiliation:
Department of Astronomy, University of Maryland at College Park, College Park, MD 20742 email: ricotti@astro.umd.edu
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Abstract

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In this talk I revisit the problem of gas accretion onto minihalos after reionization. I show that primordial minihalos with vcir < 20 km s−1 stop accreting gas after reionization, as is usually assumed, but in virtue of their increasing concentration and the decreasing temperature of the intergalactic medium as redshift decreases, they have a late phase (at redshift z<2) of gas accretion and possibly star formation. As a result we expect that pre-reionization fossils have a more complex star formation history than previously envisioned. A signature of this model is a bimodal star formation history. The dwarf spheroidal galaxy Leo T, that inspired the present work, fits with this scenario. Another prediction of the model is the existence of a population of gas rich minihalos that never formed stars. A subset of compact high-velocity clouds may be identified as such objects but the bulk of them may still be undiscovered.

Keywords

galaxies: dwarfgalaxies: evolutionLocal Groupearly universe
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Issue S255: Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies , June 2008 , pp. 142 - 146
Copyright
Copyright © International Astronomical Union 2008

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