2006ApJ...647L..29Y

We report the first detection of the 5705 and 5780 Å diffuse interstellar bands (DIBs) in a moderate-redshift damped Lyα (DLA) system. We measure a rest-frame equivalent width of 63.2±8.7 mÅ for the 5705 Å feature and 216±9 mÅ for the 5780 Å feature in the z_abs=0.524 DLA toward AO 0235+164 and derive limits for the equivalent widths of the bands at 5797, 6284, and 6613 Å. The equivalent width of the 5780 Å band is lower than would be expected based on the Galactic correlation of DIB strength with N(H I) but is in good agreement with the correlation with E(B-V). The relative strengths of the 5780 and 6284 Å DIBs are inconsistent with all Galactic and extragalactic sight lines, except one Small Magellanic Cloud wing sight line toward Sk 143. However, the relative strengths of the 5705 and 5780 Å DIBs are consistent with the Galactic relation, indicating that the relative strengths of these bands may be less sensitive to environment or that they may be associated with a similar carrier. The detection of DIBs at z∼0.5 demonstrates that the organic compounds usually assumed to be the band carriers were already present in the universe some 5 Gyr ago.