A resolved map of the infrared excess in a Lyman Break Galaxy at z= 3
Artikel i vetenskaplig tidskrift, 2016

We have observed the dust continuum of 10 z = 3.1 Lyman break galaxies with the Atacama Large Millimeter/submillimeter Array at similar to 450 mas resolution in Band 7. We detect and resolve the 870 mu m emission in one of the targets with a flux density of S-870 = 192 +/- 57 mu Jy, and measure a stacked 3 sigma signal of S-870 = 67 +/- 23 mu Jy for the remaining nine. The total infrared luminosities are L8-1000 = (8.4 +/- 2.3) x 10(10) L-circle dot for the detection and L8-1000 = (2.9 +/- 0.9) x 10(10) L-circle dot for the stack. With Hubble Space Telescope Advanced Camera for Surveys I-band imaging we map the rest-frame UV emission on the same scale as the dust, effectively resolving the "infrared excess" (IRX = L-FIR/L-UV) in a normal galaxy at z = 3. Integrated over the galaxy we measure IRX = 0.56 +/- 0.15, and the galaxy-averaged UV slope is beta = -1.25 +/- 0.03. This puts the galaxy a factor of similar to 10 below the IRX-beta relation for local starburst nuclei of Meurer et al. However, IRX varies by more than a factor of 3 across the galaxy, and we conclude that the complex relative morphology of the dust relative to UV emission is largely responsible for the scatter in the IRX-beta relation at high-z. A naive application of a Meurer-like dust correction based on the UV slope would dramatically overestimate the total star formation rate, and our results support growing evidence that when integrated over the galaxy, the typical conditions in high-z star-forming galaxies are not analogous to those in the local starburst nuclei used to establish the Meurer relation.


submillimeter: ISM

galaxies: ISM


submillimeter: galaxies

galaxies: high-redshift


M. P. Koprowski

University of Hertfordshire

K. E. K. Coppin

University of Hertfordshire

J.E. Geach

University of Hertfordshire

N. K. Hine

University of Hertfordshire

M. Bremer

University of Bristol

S. C. Chapman

Dalhousie University

L. J. M. Davies

University of Western Australia

T. Hayashino

Tohoku University

Kirsten Kraiberg Knudsen

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

M. Kubo

National Astronomical Observatory of Japan

B. D. Lehmer

University of Arkansas - Fayetteville

Y. Matsuda

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

D. J. B. Smith

University of Hertfordshire

P.P. van der Werf

Universiteit Leiden

G. Violino

University of Hertfordshire

T. Yamada

JAXA Institute of Space and Astronautical Science

Astrophysical Journal Letters

2041-8205 (ISSN) 2041-8213 (eISSN)

Vol. 828 2 L21


Astronomi, astrofysik och kosmologi


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