Near-infrared Observations of a Redshift 5.34 Galaxy: Further Evidence for Dust Absorption in the Early Universe

Imaging at 1.25 and 2.20 mm has been obtained of the field containing the galaxy (RD1) found at redshift by Dey et al. This galaxy has been detected at 1.25 mm, while the lower redshift ( ) galaxy z 5 5.34 z 5 4.02 also found in the same field by Dey et al. was detected at both 1.25 and 2.20 mm. Comparison to stellar population synthesis models indicates that if RD1 is a young ( yr) galaxy, significant reddening ( mag) is 8 t ! 10 A 1 0.5 V indicated. Combined with observations of other high-redshift systems, these data show that dust is likely to be an important component of young galaxies even at redshifts of . The extinction-corrected monochromatic z 1 5 luminosity of RD1 at 1500 Å is then a factor of about 3 larger than as determined by Dickinson for ∗ L z ∼ 1500 starburst galaxies. The implied star formation rate in RD1, corrected for extinction, is ∼50–100 M, yr. 22 3 h50 Subject headings: dust, extinction — galaxies: evolution