We have observed the radio source 3C 317 in the X-ray cooling flow cluster A2052 using the VLA at wavelengths 90, 20, 6, and 3.6 cm. Unlike most moderate-power extragalactic radio sources, 3C 317 is characterized by a compact core and an amorphous halo with an angular size of 75" × 45". The spectrum of the halo emission is unusually steep (α20/90cm ∼ -1.5 and α6/20cm ∼ -1.9). Surrounding the compact radio core at the center of the galaxy, a bipolar structure has been observed indicating that an outflow may have been initially collimated to some degree. However, no well-collimated jets have been detected with a resolution of 0".3. The lack of strong collimation could be due to jet disruption in the cooling flow on scales unresolved by the VLA observations. An observed gradient of spectral index from flat (α ∼ -0.05) at the nucleus to steep in the halo (α ∼ -1.9) also favors the hypothesis that relativistic electrons originated within the active nucleus and "aged" as they move outward. The radio morphology, the curved spectrum of the integrated flux density, and the gradient within the spectral index distribution suggest that diffusion, synchrotron losses and electron reacceleration likely play important roles in the transport of the relativistic electrons from the nucleus to the radio halo. In addition, our new observations reveal that the halo was a wealth of substructures: a loop (25 kpc × 1.5 kpc) and large-scale filaments which connect to the bipolar structure. Linear analysis suggests that these filamentary structures could form by either magnetic field reconnection or Rayleigh-Taylor instabilities. The details of this peculiar radio source provide evidence that radio plasma interacts with X-ray cooling flows in the centers of clusters.
No takes yet. Share an insight, caveat, or question.
Zhao et al. (1993) studied this question.