GOODS-HERSCHEL: star formation, dust attenuation and the FIR-radio correlation on the Main Sequence of star-forming galaxies up to z~4

Sargent, M T, Panella, M, Elbaz, D, Schreiber, C, Bethermin, M, Inami, H, Dickinson, M, Magnelli, B, Wang, T, Aussel, H, Daddi, E, Juneau, S, Shu, X, Buat, V, Faber, S M, Ferguson, H C, Giavalisco, M, Koekemoer, A M, Magdis, G, Morrison, G E, Papovich, C, Santini, P and Scott, D (2015) GOODS-HERSCHEL: star formation, dust attenuation and the FIR-radio correlation on the Main Sequence of star-forming galaxies up to z~4. The Astrophysical Journal, 807 (2).

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We use the deep panchromatic dataset available in the GOODS-N field, spanning all the way from GALEX ultra-violet to VLA radio continuum data, to select a star-forming galaxy sample at z~[0.5-4] and robustly measure galaxy photometric redshifts, star formation rates, stellar masses and UV rest-frame properties. We quantitatively explore, using mass-complete samples, the evolution of the star formation activity and dust attenuation properties of star-forming galaxies up to z~4. Our main results can be summarized as follows: i) we find that the slope of the SFR-M correlation is consistent with being constant, and equal to ~0.8 at least up to z~1.5, while the normalization keeps increasing to the highest redshift, z~4, we are able to explore; ii) for the first time in this work, we are able to explore the FIR-radio correlation for a mass-selected sample of star-forming galaxies: the correlation does not evolve up to z~4; iii) we confirm that galaxy stellar mass is a robust proxy for UV dust attenuation in star-forming galaxies, with more massive galaxies being more dust attenuated; iv) strikingly, we find that this attenuation relation evolves very weakly with redshift, the amount of dust attenuation increasing by less than 0.3 magnitudes over the redshift range [0.5-4] for a fixed stellar mass, as opposed to a tenfold increase of star formation rate; v) this finding explains the evolution of the SFR-Auv relation reported in literature: the same amount of star formation is less attenuated at higher redshift because it is hosted in less massive, and less metal rich, galaxies; vi) the correlation between dust attenuation and the UV spectral slope evolves in redshift, with the median UV spectral slope of star-forming galaxies becoming bluer with redshift. By z~3, typical UV slopes are inconsistent, given the measured dust attenuation, with the predictions of commonly used empirical laws: this means that the present cosmic star formation rate density
estimates at redshift z > 3 need to be increased by a factor of around 2. Finally, building on the measured AUV–logM correlation and on existing results, we find evidence that line reddening is marginally larger (by a factor of around 1.3) than continuum reddening at all redshifts probed, and also that the amount of dust attenuation at a fixed ISM metallicity increases with redshift. We speculate that our results point toward an evolution of the ISM conditions of the median star-forming galaxy, such that at z >1.5, Main Sequence galaxies have ISM properties more similar to those found in local starbursts.

Item Type: Article
Additional Information: Article number 141
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Mark Sargent
Date Deposited: 24 Aug 2015 11:19
Last Modified: 08 Mar 2017 08:09

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