Formation and Evolution of
Galaxy Clusters Across Cosmic Time

The central active galactic nucleus (AGN) of the galaxy cluster RBS 797 (z=0.35) is characterized by an unusual morphology. Previous VLA observations revealed four perpendicular lobes reaching a distance of 30 kpc from the center, and four perpendicular jets emanating from the radio core. Past X-ray studies of the intracluster medium revealed two pronounced X-ray cavities in the east-west (E-W) direction. Using a new Chandra observation (420 ks), we report the detection of two additional, radio filled X-ray cavities in the N-S direction at nearly the same radial distance as the E-W ones. We derive the dynamical and radiative ages of the four cavities from X-ray and radio data, respectively, finding that the two outbursts are approximately coeval, with an age difference of less than 10 Myr between the E-W and N-S cavities. We discuss two scenarios for the origin of the two perpendicular, equidistant cavity systems: either the presence of a binary AGN which is excavating coeval pairs of cavities in perpendicular directions, or a fast jet reorientation event which produced subsequent, misaligned outbursts.