The hidden side of cosmic star formation at z &gt; 3: Bridging optically-dark and Lyman break galaxies with GOODS-ALMA
Creators: name: Xiao, Mengyuan
name: Elbaz, David
name: Gómez-Guijarro, Carlos
name: Leroy, Lucas
name: Bing, Longji
name: Daddi, Emanuele
name: Magnelli, Benjamin
name: Franco, Maximilien
name: Zhou, Luwenjia
name: Dickinson, Mark
name: Wang, Tao
name: Rujopakarn, Wiphu
name: Magdis, Georgios E.
name: Treister, Ezequiel
name: Inami, Hanae
name: Demarco, Ricardo
name: Sargent, Mark T.
name: Shu, Xinwen
name: Kartaltepe, Jeyhan S.
name: Alexander, David M.
name: Béthermin, Matthieu
name: Bournaud, Frederic
name: Ciesla, Laure
name: Ferguson, Henry C.
name: Finkelstein, Steven L.
name: Giavalisco, Mauro
name: Gu, Qiusheng
name: Iono, Daisuke
name: Juneau, Stephanie
name: Lagache, Guilaine
name: Leiton, Roger
name: Messias, Hugo
name: Motohara, Kentaro
name: Mullaney, James
name: Nagar, Neil
name: Pannella, Maurilio
name: Papovich, Casey
name: Pope, Alexandra
name: Schreiber, Corentin
name: Silverman, John
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Our current understanding of the cosmic star formation history at z&gt;3 is primarily based on UV-selected galaxies (i.e., LBGs). Recent studies of H-dropouts have revealed that we may be missing a large proportion of star formation that is taking place in massive galaxies at z&gt;3. In this work, we extend the H-dropout criterion to lower masses to select optically dark/faint galaxies (OFGs), in order to complete the census between LBGs and H-dropouts. Our criterion (H&gt; 26.5 mag &amp; [4.5] &lt; 25 mag) combined with a de-blending technique is designed to select not only extremely dust-obscured massive galaxies but also normal star-forming galaxies. In total, we identified 27 OFGs at z_phot &gt; 3 (z_med=4.1) in the GOODS-ALMA field, covering a wide distribution of stellar masses with log($M_{\star}$/$M_{\odot}$) = 9.4-11.1. We find that up to 75% of the OFGs with log($M_{\star}$/$M_{\odot}$) = 9.5-10.5 were neglected by previous LBGs and H-dropout selection techniques. After performing stacking analyses, the OFGs exhibit shorter gas depletion timescales, slightly lower gas fractions, and lower dust temperatures than typical star-forming galaxies. Their SFR_tot (SFR_ IR+SFR_UV) is much larger than SFR_UVcorr (corrected for dust extinction), with SFR_tot/SFR_UVcorr = $8\pm1$, suggesting the presence of hidden dust regions in the OFGs that absorb all UV photons. The average dust size measured by a circular Gaussian model fit is R_e(1.13 mm)=1.01$\pm$0.05 kpc. We find that the cosmic SFRD at z&gt;3 contributed by massive OFGs is at least two orders of magnitude higher than the one contributed by equivalently massive LBGs. Finally, we calculate the combined contribution of OFGs and LBGs to the cosmic SFRD at z=4-5 to be 4 $\times$ 10$^{-2}$ $M_{\odot}$ yr$^{-1}$Mpc$^{-3}$, which is about 0.15 dex (43%) higher than the SFRD derived from UV-selected samples alone at the same redshift.
description: 26 pages, 14 figures, 8 tables. Accepted for publication in A&amp;A