- 3C84: radio outburst and jet outflow from the SMBH in the cooling flow cluster Abell 426 (Perseus cluster)
Located at the center of the Perseus cluster, 3C84 is a strong radio source. With the SMA and CARMA, we are monitoring the radio variations of 3C84 at submm/mm wavelengths. The radio source currently shows an increase in flux density, suggesting that 3C 84 is in a pre-flare state. The fluctuation of the flux-density curve indicates that the radio source is bubbling. As soon as the source reaching a flare state, we will ask VLBA target of opportunity (ToO) observations of the sources to study the process of jet ejection from the SMBH. Located in the center of the cooling flow cluster, 3C84 is an excellent astrophysical laboratory for testing jet formation theory. The X-ray cooling inflow appears to provide not only strong ram pressure to confine the radio plasma outflow but also a fueling mechanism for powering the central engine. The mm/submm radiation
flux monitoring and VLBA imaging along with X-ray, optical and IR observations
are the critical means to understand the ecological cycle of a SMBH at the center of a cooling flow cluster.
- 3C 317: an Amorphous Radio Source in the Cooling Flow Cluster Abell 2052
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" x 45". The spectrum of the halo emission is unusually
steep (alpha20/90cm ~ -1.5 and alpha6/20cm ~ -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 (alpha ~ -0.05) at the nucleus to steep in the halo (alpha ~ -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 x 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.
A 20 CM VLA survey of Abell clusters of galaxies. I - Distance class of not greater than 3 clusters
Nearby Abell clusters of distance class of not greater than 3 are studied based on 20-cm
VLA observations, Westerbork Synthesis Radio Telescope results, and Einstein Observatory
X-ray data. No significant correlation is found between the 20-cm radio power and X-ray
luminosity, and no evidence is found that regular-type clusters are statistically more
likely to be radio loud than irregular-type clusters. A weak correlation is noted between
X-ray-cooling mass-accretion rates and radio powers for central dominant galaxies in
cooling-flow clusters, suggesting that either cooling accretion directly fuels the central
engine and/or cooling flows strongly interact with the radio plasma.