The MOSDEF survey: the dependence of H α-to-UV SFR ratios on SFR and size at z 2
Abstract
We perform an aperture-matched analysis of dust-corrected H α and UV star formation rates (SFRs) using 303 star-forming galaxies with spectroscopic redshifts 1.36 < zspec < 2.66 from the MOSFIRE Deep Evolution Field survey. By combining H α and H β emission line measurements with multiwaveband resolved Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/3D-HST imaging, we directly compare dust-corrected H α and UV SFRs, inferred assuming a fixed attenuation curve shape and constant SFHs, within the spectroscopic aperture. Previous studies have found that H α and UV SFRs inferred with these assumptions generally agree for typical star-forming galaxies, but become increasingly discrepant for galaxies with higher SFRs (≳100 M⊙ yr-1), with H α-to-UV SFR ratios being larger for these galaxies. Our analysis shows that this trend persists even after carefully accounting for the apertures over which H α and UV-based SFRs (and the nebular and stellar continuum reddening) are derived. Furthermore, our results imply that H α SFRs may be higher in the centres of large galaxies (i.e. where there is coverage by the spectroscopic aperture) compared to their outskirts, which could be indicative of inside-out galaxy growth. Overall, we suggest that the persistent difference between nebular and stellar continuum reddening and high H α-to-UV SFR ratios at the centres of large galaxies may be indicative of a patchier distribution of dust in galaxies with high SFRs.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 2021
- DOI:
- 10.1093/mnras/stab2570
- arXiv:
- arXiv:2109.03843
- Bibcode:
- 2021MNRAS.508.1431F
- Keywords:
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- methods: data analysis;
- galaxies: evolution;
- galaxies: fundamental parameters;
- galaxies: high-redshift;
- galaxies: star formation;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 15 pages, 7 figures, accepted to MNRAS