3.1.3. Near-IR

Strong emission lines such as Pa and Pa as well as high-excitation lines such as [Si VI] can potentially be used to distinguish starbursts from AGN. Even if the extinction is still two large along the line of sight to observe emission lines from the central source, there is the potential for observing scattered emission in polarized light. Two of the four ULIGs for which sensitive near-infrared spectra exist (IRAS 05189-2524, Mrk 231) show clear evidence for polarized Seyfert 1 emission lines and [Si VI] emission, further suggesting the presence of a strong AGN.