Abstract
We present the results of a new study of dust attenuation at redshifts $3 < z
< 4$ based on a sample of $236$ star-forming galaxies from the VANDELS
spectroscopic survey. Motivated by results from the FiBY simulation project, we
argue that the intrinsic SEDs of star-forming galaxies at these redshifts have
a self-similar shape across the mass range $8.2 łeq$ log$(M_\star/M_ødot)
10.6$ probed by our sample. Using FiBY data, we construct a set of
intrinsic SED templates which incorporate both detailed star formation and
chemical abundance histories, and a variety of SPS model assumptions. With this
set of physically-motivated intrinsic SED templates, we present a novel
approach for directly recovering the shape and normalization of the dust
attenuation curve using the ratio of the intrinsic and observed SEDs. We find,
across all of the intrinsic templates considered, that the average attenuation
curve for star-forming galaxies at $z\simeq3.5$ is similar in shape to the
commonly-adopted Calzetti starburst law, with an average total-to-selective
attenuation ratio of $R_V=4.18\pm0.29$. In contrast, we find that an average
attenuation curve as steep as the SMC extinction law is strongly disfavoured.
We show that the optical attenuation ($A_V$) versus stellar mass ($M_\star$)
relation predicted using our method is consistent with recent ALMA observations
of galaxies at $2<z<3$ in the HUDF, as well as empirical $A_V - M_\star$
relations predicted by a Calzetti-like law. In fact, our results, combined with
other literature data, suggest that the $A_V - M_\star$ relation does not
evolve over the redshift range $0<z<5$, at least for galaxies with
log$(M_\star/M_ødot) 9.5$. Finally, we present tentative evidence
which suggests that the attenuation curve may become steeper at lower masses
log$(M_\star/M_ødot) 9.0$.
Description
[1712.01292] The VANDELS survey: Dust attenuation in star-forming galaxies at $\mathbf{z=3-4}$
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