IS THE BL-LACERTAE OBJECT AO-0235-II ABSORBER(164 BEING LENSED BY ITSINTERVENING MG)

We report the results of deep CFHT imaging of the BL Lac object AO 023 5 + 164. This object exhibits Mg II absorption features and has been c onsidered to be the best candidate for a microlensed BL Lac on the bas is of its multiple redshift systems, decentered host, and extreme appa rent superluminal motion. We test the microlensing hypothesis by model ing our images with a two-dimensional image fitting routine. The resul ting best-fit models allow us to put strong constraints on lensing sce narios for this object, and to put limits on the mass-to-light ratio o f the foreground Mg II absorbing galaxy. We conclude that while AO 023 5 + 164 is almost certainly being weakly amplified by macrolensing, mi crolensing by stars in the foreground lens is unnecessary in order to explain the observed properties of AO 0235 + 164. These results are co mbined with the work of previous authors to suggest that the (probably lensing) Mg II absorbing galaxy in the foreground of AO 0235 + 164 is embedded in a cooling flow.