Significant Dust-obscured Star Formation in Luminous Lyman-break Galaxies at z ∼7-8
Authors
Publication Date
2022Journal Title
Astrophysical Journal
ISSN
0004-637X
Publisher
American Astronomical Society
Volume
928
Issue
1
Language
en
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Schouws, S., Stefanon, M., Bouwens, R., Smit, R., Hodge, J., Labbé, I., Algera, H., et al. (2022). Significant Dust-obscured Star Formation in Luminous Lyman-break Galaxies at z ∼7-8. Astrophysical Journal, 928 (1) https://doi.org/10.3847/1538-4357/ac4605
Abstract
We make use of ALMA continuum observations of $15$ luminous Lyman-break
galaxies at $z$$\sim$$7$$-$$8$ to probe their dust-obscured star-formation.
These observations are sensitive enough to probe to obscured SFRs of $20$
$M_{\odot}$$/$$yr$ ($3\sigma$). Six of the targeted galaxies show significant
($\geq$$3$$\sigma$) dust continuum detections, more than doubling the number of
known dust-detected galaxies at $z$$>$$6.5$. Their IR luminosities range from
$2.7$$\times$$10^{11}$ $L_{\odot}$ to $1.1$$\times$$10^{12}$ $L_{\odot}$,
equivalent to obscured SFRs of $20$ to $105$ $M_{\odot}$$/$$yr$. We use our
results to quantify the correlation of the infrared excess IRX on the
UV-continuum slope $\beta_{UV}$ and stellar mass. Our results are most
consistent with an SMC attenuation curve for intrinsic $UV$-slopes
$\beta_{UV,intr}$ of $-2.63$ and most consistent with an attenuation curve
in-between SMC and Calzetti for $\beta_{UV,intr}$ slopes of $-2.23$, assuming a
dust temperature $T_d$ of $50$ K. Our fiducial IRX-stellar mass results at
$z$$\sim$$7$$-$$8$ are consistent with marginal evolution from $z$$\sim$$0$. We
then show how both results depend on $T_d$. For our six dust-detected sources,
we estimate their dust masses and find that they are consistent with dust
production from SNe if the dust destruction is low ($<$$90$%). Finally we
determine the contribution of dust-obscured star formation to the star
formation rate density for $UV$ luminous ($<$$-$$21.5$ mag:
$\gtrsim$$1.7$$L_{UV} ^*$) $z$$\sim$$7$$-$$8$ galaxies, finding that the total
SFR density at $z$$\sim$$7$ and $z$$\sim$$8$ from bright galaxies is
$0.18_{-0.10}^{+0.08}$ dex and $0.20_{-0.09}^{+0.05}$ dex higher, respectively,
i.e. $\sim$$\frac{1}{3}$ of the star formation in $\gtrsim$$1.7$$L_{UV} ^*$
galaxies at $z$$\sim$$7$$-$$8$ is obscured by dust.
Keywords
310, Galaxies and Cosmology
Sponsorship
ERC
STFC
Funder references
Science and Technology Facilities Council (ST/M001172/1)
European Research Council (695671)
Identifiers
apjac4605, ac4605, aas32389
External DOI: https://doi.org/10.3847/1538-4357/ac4605
This record's URL: https://www.repository.cam.ac.uk/handle/1810/335396
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
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