A RESOLVED MAP OF THE INFRARED EXCESS IN A LYMAN BREAK GALAXY AT z = 3
- Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom)
- H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4R2 (Canada)
- ICRAR, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)
- Research Center for Neutrino Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578 (Japan)
- Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden)
- National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)
- Department of Physics, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701 (United States)
- Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, 252-5210 Sagamihara, Kanagawa 252-5210 (Japan)
We have observed the dust continuum of 10 z = 3.1 Lyman break galaxies with the Atacama Large Millimeter/submillimeter Array at ∼450 mas resolution in Band 7. We detect and resolve the 870 μ m emission in one of the targets with a flux density of S {sub 870} = 192 ± 57 μ Jy, and measure a stacked 3 σ signal of S {sub 870} = 67 ± 23 μ Jy for the remaining nine. The total infrared luminosities are L {sub 8–1000} = (8.4 ± 2.3) × 10{sup 10} L {sub ⊙} for the detection and L {sub 8–1000} = (2.9 ± 0.9) × 10{sup 10} L {sub ⊙} 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 {sub FIR}/ L {sub 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 β = −1.25 ± 0.03. This puts the galaxy a factor of ∼10 below the IRX– β 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– β 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.
- OSTI ID:
- 22654225
- Journal Information:
- Astrophysical Journal Letters, Vol. 828, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
ALMA spectroscopic survey in the Hubble Ultra Deep Field: the infrared excess of UV-selected z = 2–10 galaxies as a function of UV-continuum slope and stellar mass
Dust Properties of C ii Detected z ∼ 5.5 Galaxies: New HST/WFC3 Near-IR Observations