A resolved map of the infrared excess in a Lyman Break Galaxy at z= 3
Journal article, 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.
dust
submillimeter: ISM
galaxies: ISM
extinction
submillimeter: galaxies
galaxies: high-redshift
Author
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, Earth and Space Sciences, Radio Astronomy and Astrophysics
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
Leiden University
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 L21Subject Categories
Astronomy, Astrophysics and Cosmology
Roots
Basic sciences
DOI
10.3847/2041-8205/828/2/l21