The X-ray environment of the dumbbell radio galaxy NGC 326

We report the first detailed X-ray observations of the dumbbell radio galaxy NGC 326. The region containing the source was imaged for 5.8 hr in soft X-rays with the ROSAT PSPC as part of a program to measure the X-ray emission in low-power radio galaxies not known to be in rich clusters.

Unlike other radio galaxies measured as part of this program, NGC 326 is discovered to be embedded in bright asymmetrical X-ray-emitting cluster gas of temperature kT similar to 2 keV and 0.1-2.4 keV luminosity 3.5 x 10(36) W (H-0 = 50 km s(-1) Mpc(-1)). There is a peak in the X-ray emission consistent with the location of the radio galaxy core. Five of the 10 brightest galaxies in the region are the brightest optical objects in error circles of excess X-ray emission. In the same observation, ROSAT also detected the unrelated, more distant, cluster Abell 115 and provided its first spectral measurement: kT = 7.2(-1.9)(+9) keV.

It has been suggested previously that galaxy kinematics are responsible for the apparent change in direction over time of the twin jets of the large-scale radio emission of NGC 326. This was thought to be due either to a misalignnent between the radio beam and galaxy axes or to interaction between the two galaxies which form the dumbell nucleus of NGC 326 and which are known to be passing at about 16 kpc projected separation. Our X-ray results support a different explanation: that buoyancy forces have bent the outer radio structure.