Using Chandra imaging spectroscopy and VLA L-band maps, we have identified radio galaxies at P(1.4 GHz) >= 3x10^{23} W Hz^{-1} and X-ray point sources (XPSs) at L(0.3-8 keV) >= 10^{42} ergs s^{-1} in 11 moderate redshift (0.2<z<0.4) clusters of galaxies. Each cluster is uniquely chosen to have a total mass similar to predicted progenitors of the present-day Coma Cluster. Within a projected radius of 1 Mpc we detect 20 radio galaxies and 8 XPSs confirmed to be cluster members above these limits. 75% of these are detected within 500 kpc of the cluster center. This result is inconsistent with a random selection from bright, red sequence ellipticals at the > 99.999% level. All but one of the XPSs are hosted by luminous ellipticals which otherwise show no other evidence for AGN activity. These objects are unlikely to be highly obscured AGN since there is no evidence for large amounts of X-ray or optical absorption. The most viable model for these sources are low luminosity BL Lac Objects. The expected numbers of lower luminosity FR 1 radio galaxies and BL Lacs in our sample converge to suggest that very deep radio and X-ray images of rich clusters will detect AGN in a large fraction of bright elliptical galaxies in the inner 500 kpc. Because both the radio galaxies and the XPSs possess relativistic jets, they can inject heat into the ICM. Using the most recent scalings of P_jet ~ L_radio^{0.5} from Birzan et al. (2008), radio sources weaker than our luminosity limit probably contribute the majority of the heat to the ICM. If a majority of ICM heating is due to large numbers of low power radio sources, triggered into activity by the increasing ICM density as they move inward, this may be the feedback mechanism necessary to stabilize cooling in cluster cores.
We present radio observations of ultraluminous infrared galaxies (ULIRGs) using the Giant Metrewave Radio Telescope (GMRT) and combine them with archival multi-frequency observations to understand whether ULIRGs are the progenitors of the powerful radio loud galaxies in the local Universe. ULIRGs are characterized by large infrared luminosities ($L_{IR}>$10$^{12}$L$\odot$), large dust masses ($\sim10^{8}M_{\odot}$) and vigorous star formation (star formation rates $\sim$10-100 $M_{\odot}~$yr$^{-1}$). Studies show that they represent the end stages of mergers of gas-rich spiral galaxies. Their …
{We simulate the evolution of relativistic electrons injected into the intracluster medium by five radio galaxies. We study the spatial transport and the emission properties of the injected radio plasma over a $\sim 5$ Gyr period, and the sequence of cooling and re-acceleration events experienced by electrons, using a Lagrangian approach joint with a numerical method to model the evolution of momentum spectra of relativistic electrons. When compared with electrons injected by shock waves, electrons injected by radio galaxies (here limited to a single injection event) in our tests are unable to…
Many massive early-type galaxies host central radio sources and hot X-ray atmospheres indicating the presence of radio-mechanical active galactic nucleus (AGN) feedback. The duty cycle and detailed physics of the radio-mode AGN feedback is still a matter of debate. To address these questions, we present 1-2 GHz Karl G. Jansky Very Large Array (VLA) radio observations of a sample of the 42 nearest optically and X-ray brightest early-type galaxies. We detect radio emission in 41/42 galaxies. However, the galaxy without a radio source, NGC 499, has recently been detected at lower frequencies by t…
