Search for free-free absorption cutoffs from tori in three type 2 active galactic nuclei

We have observed three type 2 radio-loud active galactic nuclei using the Very Large Baseline Array at five frequencies between 1.6 and 15 GHz in a search for the free-free absorption cutoff predicted by some models for optically obscuring dusty molecular tori. We find no evidence for sharp cutoffs toward low frequencies in any of the sources. However, one source, OW 637, has VLBI components that fall steeply toward high frequencies (S-nu proportional to nu(-2)).