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 mu m has been obtained of the field containing the galaxy (RD1) found at redshift z = 5.34 by Dey et al. This galaxy has been detected at 1.25 mu m, while the lower redshift (z = 4.02) galaxy also found in the same field by Dey et al. was detected at both 1.25 and 2.20 mu m. Comparison to stellar population synthesis models indicates that if RD1 is a young (t < 10(8) yr) galaxy, significant reddening (A(V) > 0.5 mag) is 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 z > 5. The extinction-corrected monochromatic luminosity of RD1 at 1500 Angstrom is then a factor of about 3 larger than L*(1500) as determined by Dickinson for z similar to 3 starburst galaxies. The implied star formation rate in RD1, corrected for extinction, is similar to 50-100 h(50)(-2) M(circle dot) yr(-1).