University Of Tasmania
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The ACS LCID Project. XI. On the early time resolution of SFHs of local group dwarf galaxies: comparing the effects of reionization in models with observations

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journal contribution
posted on 2023-05-18, 23:57 authored by Aparicio, A, Hidalgo, SL, Skillman, E, Cassisi, S, Mayer, L, Navarro, J, Andrew ColeAndrew Cole, Gallart, C, Monelli, M, Weisz, D, Bernard, E, Dolphin, A, Stetson, P
The analysis of the early star formation history (SFH) of nearby galaxies, obtained from their resolved stellar populations, is relevant as a test for cosmological models. However, the early time resolution of observationally derived SFHs is limited by several factors. Thus, direct comparison of observationally derived SFHs with those derived from theoretical models of galaxy formation is potentially biased. Here we investigate and quantify this effect. For this purpose, we analyze the duration of the early star formation activity in a sample of four Local Group dwarf galaxies and test whether they are consistent with being true fossils of the pre-reionization era; i.e., if the quenching of their star formation occurred before cosmic reionization by UV photons was completed. Two classical dSph (Cetus and Tucana) and two dTrans (LGS-3 and Phoenix) isolated galaxies with total stellar masses between 1.3 x 106 and 7.2 x 106 M have been studied. Accounting for time resolution effects, the SFHs peak as much as 1.25 Gyr earlier than the optimal solutions. Thus, this effect is important for a proper comparison of model and observed SFHs. It is also shown that none of the analyzed galaxies can be considered a true fossil of the pre-reionization era, although it is possible that the outer regions of Cetus and Tucana are consistent with quenching by reionization.


Publication title

The Astrophysical Journal



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School of Natural Sciences


American Astronomical Society

Place of publication

Chicago, USA

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Copyright 2016 The American Astronomical Society

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  • Open

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Expanding knowledge in the physical sciences