April
2026
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2026ApJ..1000..225S
Authors
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Sattari, Zahra
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Kelson, Daniel D.
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Mobasher, Bahram
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Chartab, Nima
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Mehta, Vihang
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Teplitz, Harry I.
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Patel, Shannon G.
Abstract
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We present a spectroscopic study of low-mass galaxies (LMGs;108 ≤ M*/M⊙ ≤ 109) at z ∼ 0.15 in the Cosmic Evolution Survey field, and compare it to a control sample of intermediate-mass galaxies (IMGs; 109 ≤ M*/M⊙ ≤ 1010) at z ∼ 0.35. We examine their star formation rates (SFRs), dust attenuation properties, and the relationship between nebular and stellar reddening. For both samples, SFRs derived from Hα are strongly correlated with SFRs from fitting simple star formation histories (SFHs) to the galaxies' spectral energy distributions. In fitting a joint SFR─M* relation, we obtain a slope of ∆log(SFRHα)/∆log(M*/M⊙)=1.01±0.03 , indicating that fair ensembles of SFHs for galaxies at these stellar masses are well described by scale-free, self-similar forms. We also examine their dust attenuation properties and the relationship between nebular and stellar reddening, exploring how these quantities vary with stellar mass and specific star formation rate (sSFR). Nebular attenuation increases with stellar mass for IMGs but is lower and less mass dependent in LMGs, consistent with their reduced dust content. In all cases, stellar continuum attenuation is lower than nebular attenuation, as expected from the two-component dust model. The nebular-to-stellar color excess ratio in both samples is consistent with the canonical factor of 2.27. The ratio is mass independent, but rises with sSFR in IMGs and remains constant in LMGs. These results suggest that in LMGs, efficient dispersal of birth clouds keeps the differential attenuation approximately constant across sSFR. Thus, although LMGs follow the same global SFR─M* scaling as massive galaxies, their lower dust content and feedback-maintained ISM produce distinct attenuation behavior relative to IMGs.
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