Spatially-Offset AGN Candidates in the CLASS Survey
  Prompted by a recent claim by Barrows et al. that X-ray AGN are often found
significantly offset from the centres of their host galaxies, we have looked
for examples of compact radio sources which are offset from the optical
centroids of nearby (z < 0.2) galaxies. We have selected a sample of 345
galaxies from the Sloan Digital Sky Survey (SDSS) galaxy catalog which have
nearby compact radio sources listed in the Cosmic-Lens All Sky Survey (CLASS)
catalog. We find only three matches (0.87 per cent of the sample) with offsets
greater than 600 milliarcsec (mas), which is considerably fewer than we would
have expected from the Barrows et al. X-ray survey. We fit our histogram of
offsets with a Rayleigh distribution with {\sigma} = 60.5 mas, but find that
there is an excess of objects with separations greater than approximately 150
mas. Assuming that this excess represents AGN with real offsets, we place an
upper limit of approximately 17 per cent on the fraction of offset AGN in our
radio-selected sample. We select 38 objects with offsets greater than 150 mas,
and find they have some diverse properties: some are well known, such as Mrk
273 and Arp 220, and others have dust lanes which may have affected the optical
astrometry, while a few are strong new candidates for offset AGN.
