BLUE LOBE GALAXIES IN THE COOLING FLOW CLUSTER ABELL-1795 AND ABELL-2597

We present CCD color imagery for the centrally dominant galaxies in the clusters A1795 and A2597. These objects, which reside at the centers of large cluster cooling flows, have unusually blue central colors, spatially extended emission-line structures, and strong radio sources. Using difference images formed by modeling and subtracting the background galaxy from our U-band and Stromgren b-band images, we find prominent lobelike continuum structures in their central 10-20 kpc. In addition, we find absorption features which can be plausibly attributed to dust. Using U-I color maps, we show that the continuum lobes are very blue and occur on or near bright radio-source structures. If the blue lobes are due to young stars, this spatial correlation suggests that an interaction between the radio sources and the ambient gaseous intracluster medium may have induced the star formation. If this is a common phenomenon in cluster cooling flows, it could help to explain the scatter in the correlations between color and mass-accretion rate. It may also help explain why blue color anomalies in cluster cooling flows occur preferentially in the inner 5-20 kpc, similar to the size scales of their radio-source structures. Other interpretations for the color structure include the blue debris from recent mergers or scattered nonthermal radiation from an active nucleus. The color and radio properties of these objects are qualitatively similar but smaller in luminosity and spatial extent to those found in high redshift radio galaxies. The physical mechanism(s) responsible for the lobe structures in A1795 and A2597 may be relevant to understanding ''the alignment effect'' found in high redshift radio galaxies.