The MUSE Hubble Ultra Deep Field Survey.

Star-forming galaxies have been found to follow a relatively tight relation between stellar mass (M_*) and star formation rate (SFR), dubbed the "star formation sequence". A turnover in the sequence has been observed, where galaxies with M_* <  10¹⁰ M_⊙ follow a steeper relation than their higher mass counterparts, suggesting that the low-mass slope is (nearly) linear. In this paper, we characterise the properties of the low-mass end of the star formation sequence between 7 ≤ log M_*[M_⊙]  ≤  10.5 at redshift 0.11 <  z  <   0.91. We use the deepest MUSE observations of the Hubble Ultra Deep Field and the Hubble Deep Field South to construct a sample of 179 star-forming galaxies with high signal-to-noise emission lines. Dust-corrected SFRs are determined from Hβ λ4861 and Hα λ6563. We model the star formation sequence with a Gaussian distribution around a hyperplane between logM_*, logSFR, and log(1 + z), to simultaneously constrain the slope, redshift evolution, and intrinsic scatter. We find a sub-linear slope for the low-mass regime where log SFR [M_⊙yr⁻¹] = 0.83^+0.07_−0.06 log M_*[M_⊙]+1.74^+0.66_−0.68 log(1 + z) log SFR [ M ⊙ yr − 1 ] = 0. 83 − 0.06 + 0.07 log M ∗ [ M ⊙ ] + 1. 74 − 0.68 + 0.66 log (1 + z) $ \log \text{ SFR}[M_{\odot}\,{\mathrm{yr}}^{-1}] = 0.83^{+0.07}_{-0.06}\log{M_{*}}[M_{\odot}] + {1.74^{+0.66}_{-0.68}}{\log (1+z)} $ , increasing with redshift. We recover an intrinsic scatter in the relation of σ_intr = 0.44^+0.05_−0.04 σ intr = 0. 44 − 0.04 + 0.05 $ \sigma_{\text{ intr}}={0.44^{+0.05}_{-0.04}} $ , dex, larger than typically found at higher masses. As both hydrodynamical simulations and (semi-)analytical models typically favour a steeper slope in the low-mass regime, our results provide new constraints on the feedback processes which operate preferentially in low-mass halos. [ABSTRACT FROM AUTHOR]