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The ACS LCID project. X. The star formation history of IC 1613: revisiting the over-cooling problem


Skillman, ED and Hidalgo, SL and Weisz, DR and Monelli, M and Gallart, C and Aparicio, A and Bernard, EJ and Boylan-Kolchin, M and Cassisi, S and Cole, AA and Dolphin, AE and Ferguson, HC and Mayer, L and Navarro, JF and Stetson, PB and Tolstoy, E, The ACS LCID project. X. The star formation history of IC 1613: revisiting the over-cooling problem, The Astrophysical Journal, 786, (1) Article 44. ISSN 0004-637X (2014) [Refereed Article]


Copyright Statement

Copyright 2014 The American Astronomical Society

DOI: doi:10.1088/0004-637X/786/1/44


We present an analysis of the star formation history (SFH) of a field near the half-light radius in the Local Group dwarf irregular galaxy IC 1613 based on deep Hubble Space Telescope Advanced Camera for Surveys imaging. Our observations reach the oldest main sequence turn-off, allowing a time resolution at the oldest ages of ~1 Gyr. Our analysis shows that the SFH of the observed field in IC 1613 is consistent with being constant over the entire lifetime of the galaxy. These observations rule out an early dominant episode of star formation in IC 1613. We compare the SFH of IC 1613 with expectations from cosmological models. Since most of the mass is in place at early times for low-mass halos, a naive expectation is that most of the star formation should have taken place at early times. Models in which star formation follows mass accretion result in too many stars formed early and gas mass fractions that are too low today (the "over-cooling problem"). The depth of the present photometry of IC 1613 shows that, at a resolution of ~1 Gyr, the star formation rate is consistent with being constant, at even the earliest times, which is difficult to achieve in models where star formation follows mass assembly.

Item Details

Item Type:Refereed Article
Keywords:early universe, dwarf galaxies, galaxy evolution, galaxies: structure
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cole, AA (Professor Andrew Cole)
ID Code:97401
Year Published:2014
Web of Science® Times Cited:59
Deposited By:Mathematics and Physics
Deposited On:2014-12-16
Last Modified:2017-11-06
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