Kavli Affiliate: John Silverman
| First 5 Authors: Mengyuan Xiao, David Elbaz, Carlos Gómez-Guijarro, Lucas Leroy, Longji Bing
| Summary:
Our current understanding of the cosmic star formation history at z>3 is
primarily based on UV-selected galaxies (i.e., LBGs). Recent studies of
H-dropouts revealed that we may be missing a large amount of star formation
taking place in massive galaxies at z>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>
26.5 mag & [4.5] < 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 identify 27 OFGs at z_phot > 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 are neglected by previous LBGs and
H-dropout selection techniques. After performing stacking analysis, 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 = $8pm1$, 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>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.
| Search Query: ArXiv Query: search_query=au:”John Silverman”&id_list=&start=0&max_results=10