U-BAND POLARIMETRY OF THE RADIO-ALIGNED OPTICAL CONTINUUM IN THE ABELL-1795 CLUSTER CENTRAL GALAXY

We have obtained U-band polarimetry of the lobes of blue optical conti nuum located along the z = 0.063 F-R I radio source in the Abell 1795 cluster central galaxy. We find an upper limit to the degree of polari zation of the light emitted from the lobes of less than 7%. The accura cy of this measurement is limited by the presence of diluting backgrou nd starlight. This limit is inconsistent with the lobes being scattere d light that originated in an obscured, anisotropically radiating nucl eus, unless the radiation is beamed and is viewed at an angle less tha n or similar to 22 degrees to the line of sight, which is unlikely. Th e absence of a polarized signal and detailed correspondence between th e radio lobes and optical lobes is inconsistent with synchrotron light . The blue optical lobes are probably regions of recent star formation . If a burst of star formation were triggered by the expanding radio l obes, the age of the burst population should be similar to 10(7) yr. T hen, the star formation rate in both lobes, assuming the local IMF, is similar to 20 M(circle dot)yr(-1), and the stellar mass of the lobes is similar to 10(8) M(circle dot). The material fueling the star forma tion and the radio source may have originated from the cooling how or accretion from one or more gaseous cluster galaxies.