We report the detection of rest–frame 6.2 and 7.7 µm emission features arising from Polycyclic Aromatic Hydrocarbons ( PAH ) in the Spitzer/IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01 .
This is currently the highest redshift galaxy where these PAH emission features have been detected .
The total infrared luminosity inferred from the MIPS 24 µm and radio flux density is 2 \times 10 ^ { 13 } L _ { \odot } , which qualifies this object as a so–called hyperluminous infrared galaxy ( HyLIRG ) .
However , unlike local HyLIRGs which are generally associated with QSO/AGNs and have weak or absent PAH emission features , this HyLIRG has very strong 6.2 and 7.7 µm PAH emission .
We argue that intense star formation dominates the infrared emission of this source , although we can not rule out the presence of a deeply obscured AGN .
This LBG appears to be a distorted system in the HST ACS F606W and F814W images , possibly indicating that a significant merger or interaction is driving the large IR luminosity .