2021MNRAS.501.2231S

Extragalactic studies have demonstrated that there is a moderately tight (≃0.3 dex) relationship between galaxy stellar mass (M_*) and star formation rate (SFR) that holds for star-forming galaxies at M_* ∼ 3 x 10⁸-10¹¹ M_☉, i.e. the 'star formation main sequence'. However, it has yet to be determined whether such a relationship extends to even lower mass galaxies, particularly at intermediate or higher redshifts. We present new results using observations for 714 narrow-band H α-selected galaxies with stellar masses between 10⁶ and 10¹⁰ M_☉ (average of 10^8.2 M_☉) at z ≃ 0.07-0.5. These galaxies have sensitive ultraviolet (UV) to near-infrared photometric measurements and optical spectroscopy. The latter allows us to correct our H α SFRs for dust attenuation using Balmer decrements. Our study reveals that: (1) for low-SFR galaxies, our H α SFRs systematically underpredict compared to far-UV measurements, consistent with other studies; (2) at a given stellar mass (≃10⁸ M_☉), log (specific SFR) evolves as A log (1 + z) with A = 5.26 ± 0.75, and on average, specific SFR increases with decreasing stellar mass; (3) the SFR-M_* relation holds for galaxies down to ∼10⁶ M_☉ (∼1.5 dex below previous studies), and over lookback times of up to 5 Gyr, follows a redshift-dependent relation of log (SFR) ∝ α log (M_*/M_☉) + β z with α = 0.60 ± 0.01 and β = 1.86 ± 0.07; and (4) the observed dispersion in the SFR-M_* relation at low stellar masses is ≃0.3 dex. Accounting for survey selection effects using simulated galaxies, we estimate that the true dispersion is ≃0.5 dex.