Kavli Affiliate: Alexander P. Ji
| First 5 Authors: Yuan-Sen Ting, Alexander P. Ji, , ,
| Summary:
Dwarf galaxy star formation histories are theoretically expected to be
bursty, potentially leaving distinct imprints on their chemical evolution. We
propose that episodic starbursts with quiescent periods longer than $sim$100
Myr should lead to discontinuous tracks in a dwarf galaxy’s
[$alpha$/Fe]-[Fe/H] chemical abundance plane, with metallicity gaps as large
as 0.3-0.5 dex at [Fe/H] = -2. This occurs due to continued Fe production by
Type Ia supernovae during quiescent periods. We demonstrate that Gaussian
mixture models can statistically distinguish discontinuous and continuous
tracks based on the Akaike Information Criterion. Applying this method to
APOGEE observations of the Sculptor dSph galaxy suggests an episodic star
formation history with $sim$300 Myr quiescent periods. While current dwarf
galaxy datasets are limited by small spectroscopic sample sizes, future surveys
and extremely large telescopes will enable determining large numbers of precise
chemical abundances, opening up the investigation of very short timescales in
early dwarf galaxy formation. This unprecedentedly high time resolution of
dwarf galaxy formation in the early Universe has important implications for
understanding both reionization in the early Universe and the episodic star
formation cycle of dwarf galaxies.
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