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Star Formation Conditions in Low-Mass Galaxies: Probing the z ~ 0.6 Dwarf Population with Deep Spectroscopy from HALO7D

Presentation #324.05 in the session “Galaxy Evolution”.

Published onJun 18, 2021
Star Formation Conditions in Low-Mass Galaxies: Probing the z ~ 0.6 Dwarf Population with Deep Spectroscopy from HALO7D

Low-mass galaxies (with stellar mass M < 109 MSun), or “dwarf” galaxies, are a useful probe of the mechanisms that affect and regulate gas properties and star formation. Because gas can more easily be heated and expelled from the shallow gravitational well of a low-mass galaxy, models suggest these galaxies may occupy more distinctive positions within common empirical relations, including the mass-metallicity relation and star forming main sequence. They are also thought to exhibit more bursty star formation (SF), with SF beginning and quenching on shorter timescales compared to more massive counterparts. This effect is observed among dwarf galaxies in the local Universe, but the properties of low-mass galaxies are much less well understood at intermediate redshift, where their faintness makes observation difficult. Here we present some results from a galaxy redshift catalog derived from deep optical DEIMOS spectra taken as part of the HALO7D survey, a Keck program targeting 4 CANDELS fields. Through the identification of emission and absorption lines, we fit redshifts for >1000 galaxies, spanning a redshift range of 0.4 < z < 1.5. We also find a sample of ~250 low-mass galaxies with at least two significant spectral features securing the redshift fit, primarily in the range 0.4 < z < 0.8. This sample at intermediate redshift will extend our understanding of the SF and gas properties of low-mass galaxies beyond our local universe toward the epoch of peak star formation. We measure star formation rate and gas-phase metallicity via the O/H ratio, and we show their relations with other properties of galaxies, such as stellar mass and local environment.


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