TY - JOUR
T1 - Dust attenuation in 2<z<3 star-forming galaxies from deep ALMA observations of the Hubble Ultra Deep Field
AU - McLure, R. J.
AU - Dunlop, J. S.
AU - Cullen, F.
AU - Bourne, N.
AU - Best, P. N.
AU - Khochfar, S.
AU - Bowler, R. A. A.
AU - Biggs, A. D.
AU - Geach, J. E.
AU - Scott, D.
AU - Michalowski, M. J.
AU - Rujopakarn, W.
AU - Kampen, E. van
AU - Kirkpatrick, A.
AU - Pope, A.
N1 - 17 pages, 7 figures, accepted version to be published in MNRAS
PY - 2018/5/21
Y1 - 2018/5/21
N2 - We present the results of a new study of the relationship between infrared excess (IRX ≡ L
IR/L
UV), ultraviolet (UV) spectral slope (β) and stellar mass at redshifts 2 < z < 3, based on a deep Atacama Large Millimeter Array (ALMA) 1.3-mm continuum mosaic of the Hubble Ultra Deep Field. Excluding the most heavily obscured sources, we use a stacking analysis to show that z ≃ 2.5 star-forming galaxies in the mass range 9.25 ≤ log(M*/M
⊙) ≤ 10.75 are fully consistent with the IRX-β relation expected for a relatively grey attenuation curve, similar to the commonly adopted Calzetti law. Based on a large, mass-complete sample of 2 ≤ z ≤ 3 star-forming galaxies drawn frommultiple surveys, we proceed to derive a new empirical relationship between β and stellar mass, making it possible to predict UV attenuation (A1600) and IRX as a function of stellar mass, for any assumed attenuation law. Once again, we find that z ≃ 2.5 star-forming galaxies follow A1600-M* and IRX-M* relations consistent with a relatively grey attenuation law, and find no compelling evidence that star-forming galaxies at this epoch follow a reddening law as steep as the Small Magellanic Cloud (SMC) extinction curve. In fact, we use a simple simulation to demonstrate that previous determinations of the IRX-β relation may have been biased towards low values of IRX at red values of β, mimicking the signature expected for an SMC-like dust law. We show that this provides a plausible mechanism for reconciling apparently contradictory results in the literature and that, based on typical measurement uncertainties, stellar mass provides a cleaner prediction of UV attenuation than β. Although the situation at lower stellar masses remains uncertain, we conclude that for 2 < z < 3 star-forming galaxies with log(M*/M
⊙) ≥ 9.75, both the IRX-β and IRX-M* relations are well described by a Calzetti-like attenuation law.
AB - We present the results of a new study of the relationship between infrared excess (IRX ≡ L
IR/L
UV), ultraviolet (UV) spectral slope (β) and stellar mass at redshifts 2 < z < 3, based on a deep Atacama Large Millimeter Array (ALMA) 1.3-mm continuum mosaic of the Hubble Ultra Deep Field. Excluding the most heavily obscured sources, we use a stacking analysis to show that z ≃ 2.5 star-forming galaxies in the mass range 9.25 ≤ log(M*/M
⊙) ≤ 10.75 are fully consistent with the IRX-β relation expected for a relatively grey attenuation curve, similar to the commonly adopted Calzetti law. Based on a large, mass-complete sample of 2 ≤ z ≤ 3 star-forming galaxies drawn frommultiple surveys, we proceed to derive a new empirical relationship between β and stellar mass, making it possible to predict UV attenuation (A1600) and IRX as a function of stellar mass, for any assumed attenuation law. Once again, we find that z ≃ 2.5 star-forming galaxies follow A1600-M* and IRX-M* relations consistent with a relatively grey attenuation law, and find no compelling evidence that star-forming galaxies at this epoch follow a reddening law as steep as the Small Magellanic Cloud (SMC) extinction curve. In fact, we use a simple simulation to demonstrate that previous determinations of the IRX-β relation may have been biased towards low values of IRX at red values of β, mimicking the signature expected for an SMC-like dust law. We show that this provides a plausible mechanism for reconciling apparently contradictory results in the literature and that, based on typical measurement uncertainties, stellar mass provides a cleaner prediction of UV attenuation than β. Although the situation at lower stellar masses remains uncertain, we conclude that for 2 < z < 3 star-forming galaxies with log(M*/M
⊙) ≥ 9.75, both the IRX-β and IRX-M* relations are well described by a Calzetti-like attenuation law.
KW - Galaxies: evolution
KW - Galaxies: high-redshift
KW - Galaxies: star formation
KW - Galaxies: starburst
KW - Submillimetre: galaxies
UR - http://www.scopus.com/inward/record.url?scp=85047996106&partnerID=8YFLogxK
U2 - 10.1093/mnras/sty522
DO - 10.1093/mnras/sty522
M3 - Article
SN - 0035-8711
VL - 476
SP - 3991
EP - 4006
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -