CCD SURFACE PHOTOMETRY OF THE LOW-LUMINOSITY RADIO GALAXIES CONTAINING RADIO JETS B-2-0034+25 AND B-2-0206+35

We present broad-band CCD imaging of the radio galaxies B2 0034+25 and B2 0206+36. Both galaxies are of low radio power and contain radio jets at the arcsec scale. The galaxies have close companions and the optical morphology suggests that they are interacting. The surface photometry method and its application to interacting galaxies is described. It involves the following steps: 1) isophotal ellipse fitting of the main galaxy after semi-automatic deletion of interfering images, 2) construction of a quasi-elliptical model of the main galaxy from the best-fit parameters, 3) subtraction of the model from the original image. These steps are applied consecutively to each companion galaxy. An estimate of the photometric accuracy is obtained by applying this method to realistic simulations of galaxy pairs. This technique is found to be a powerful tool for studying galaxy interactions allowing the detection of photometric effects of the interaction such as non-concentric isophotes and deviations of the galaxy surface brightness profiles in the outer parts from the extrapolation of a de Vaucouleurs law fitted to the inner parts of the galaxy. In particular the two objects discussed in this paper appear to be strongly interacting with nearby companions. We estimate lower limits for the radio-to-optical spectral indices of the jets and conclude that the optical emission from the inner parts of the jets lies below a power-law extrapolated from radio wavelengths. The role of hot gas around elliptical galaxies on the collimation of the radio jets is briefly discussed.