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The MUSE Hubble Ultra Deep Field Survey: XI. Constraining the low-mass end of the stellar mass - Star formation rate relation at z < 1

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Boogaard, LA 
Brinchmann, J 
Bouché, N 
Paalvast, M 
Bacon, R 


jats:pStar-forming galaxies have been found to follow a relatively tight relation between stellar mass (jats:italicM</jats:italic>jats:sub</jats:sub>) and star formation rate (SFR), dubbed the “star formation sequence”. A turnover in the sequence has been observed, where galaxies with jats:italicM</jats:italic>jats:sub</jats:sub> <  10jats:sup10</jats:sup> jats:italicM</jats:italic>jats:sub⊙</jats:sub> 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 jats:italicM</jats:italic>jats:sub</jats:sub>[jats:italicM</jats:italic>jats:sub⊙</jats:sub>]  ≤  10.5 at redshift 0.11 <  jats:italicz</jats:italic>  <   0.91. We use the deepest MUSE observations of the jats:italicHubble</jats:italic> Ultra Deep Field and the jats:italicHubble</jats:italic> 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 Hjats:italicβ</jats:italic> jats:italicλ</jats:italic>4861 and Hjats:italicα</jats:italic> jats:italicλ</jats:italic>6563. We model the star formation sequence with a Gaussian distribution around a hyperplane between logjats:italicM</jats:italic>jats:sub</jats:sub>, logSFR, and log(1 + jats:italicz</jats:italic>), to simultaneously constrain the slope, redshift evolution, and intrinsic scatter. We find a sub-linear slope for the low-mass regime where log SFR [jats:italicM</jats:italic>jats:sub⊙</jats:sub>yrjats:sup−1</jats:sup>] = 0.83jats:sup+0.07</jats:sup>jats:sub−0.06</jats:sub> log jats:italicM</jats:italic>jats:sub*</jats:sub>[jats:italicM</jats:italic>jats:sub⊙</jats:sub>]+1.74jats:sup+0.66</jats:sup>jats:sub−0.68</jats:sub> log(1 + jats:italicz</jats:italic>), increasing with redshift. We recover an intrinsic scatter in the relation of jats:italicσ</jats:italic>jats:subintr</jats:sub> = 0.44jats:sup+0.05</jats:sup>jats:sub−0.04</jats:sub>, 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.</jats:p>



galaxies: star formation, galaxies: formation, galaxies: evolution, galaxies: ISM, methods: statistical

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Astronomy and Astrophysics

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EDP Sciences