Using Chandra X-ray and VLA radio data, we investigate the scaling relationship between jet power, P jet , and synchrotron luminosity, P radio . We expand the sample presented in Bîrzan et al. (2008) to lower radio power by incorporating measurements for 21 gEs to determine if the Bîrzan et al. (2008) P jet -P radio scaling relations are continuous in form and scatter from giant elliptical galaxies (gEs) up to brightest cluster galaxies (BCGs). We find a mean scaling relation of P jet ≈ 5.8 × 10 43 (P radio /10 40 ) 0.70 erg s −1 which is continuous over ∼ 6 − 8 decades in P jet and P radio with a scatter of ≈ 0.7 dex. Our mean scaling relationship is consistent with the model presented in Willott et al. (1999) if the typical fraction of lobe energy in non-radiating particles to that in relativistic electrons is > ∼ 100. We identify several gEs whose radio luminosities are unusually large for their jet powers and have radio sources which extend well beyond the densest parts of their X-ray halos. We suggest that these radio sources are unusually luminous because they were unable to entrain appreciable amounts of gas.
We present Chandra X-ray observations of the Hydra A cluster of galaxies, and we report the discovery of structure in the central 80 kpc of the cluster's X-ray-emitting gas. The most remarkable structures are depressions in the X-ray surface brightness, approximately 25-35 kpc in diameter, that are coincident with Hydra A's radio lobes. The depressions are nearly devoid of X-ray-emitting gas, and there is no evidence for shock-heated gas surrounding the radio lobes. We suggest that the gas within the surface brightness depressions was displaced as the radio lobes expanded subsonically, leaving cavities in the hot atmosphere. The gas temperature declines from 4 keV at 70 kpc to 3 keV in the inner 20 kpc of the brightest cluster galaxy (BCG), and the cooling time of the gas is approximately 600 Myr in the inner 10 kpc. These properties are consistent with the presence of an approximately 34 M middle dot in circle yr-1 cooling flow within a 70 kpc radius. Bright X-ray emission is present in the BCG surrounding a recently accreted disk of nebular emission and young stars. The star formation rate is commensurate with the cooling rate of the hot gas within the volume of the disk, although the sink for the material that may be cooling at larger radii remains elusive. A bright, unresolved X-ray source is present in the BCG's nucleus, coincident with the radio core. Its X-ray spectrum is consistent with a power law absorbed by a foreground NH approximately 4x1022 cm-2 column of hydrogen. This column is roughly consistent with the hydrogen column seen in absorption toward the less, similar24 pc diameter VLBA radio source. Apart from the point source, no evidence for excess X-ray absorption above the Galactic column is found.
We present the first results from a 500 ks Chandra ACIS-I observation of M87. At soft energies (0.5Y1.0 keV), we detect filamentary structures associated with the eastern and southwestern X-ray and radio arms. Many filaments are spatially resolved with widths of $300 pc. This filamentary structure is particularly striking in the eastern arm, where we suggest the filaments are outer edges of a series of plasma-filled, buoyant bubbles whose ages differ by $6 ; 10 6 yr. These X-ray structures may be influenced by magnetic filamentation. At hard energies (3.5Y7.5 keV), we detect a nearly circular ring of outer radius 2.8 0 (13 kpc), which provides an unambiguous signature of a weak shock, driven by an outburst from the supermassive black hole (SMBH ). The density rise in the shock is shock / 0 % 1:3 (Mach number, M % 1:2). The observed spectral hardening in the ring corresponds to a temperature rise T shock /T 0 % 1:2, or M % 1:2, in agreement with the Mach number derived independently from the gas density. Thus, for the first time, we detect gas temperature and density jumps associated with a classical shock in the atmosphere around a SMBH. We also detect two additional surface brightness edges and pressure enhancements at radii of $0.6 0 and $1 0 . The $0.6 0 feature may be overpressurized thermal gas surrounding the relativistic plasma in the radio cocoon, the ''piston,'' produced by the current episode of AGN activity. The overpressurized gas is surrounded by a cool gas shell. The $1 0 feature may be an additional weak shock from a secondary outburst. In an earlier episode, the piston was responsible for driving the 2.8 0 shock.
We present a systematic investigation of X-ray thermal coronae in 157 early-type galaxies and 22 late-type galaxies from a survey of 25 hot (kT > 3 keV), nearby (z < 0.05) clusters, based on Chandra archival data. Cool galactic coronae (kT = 0.5 -1.1 keV generally) have been found to be very common, > 60% in NIR selected galaxies that are more luminous than 2 L * , and > 40% in L * < L Ks < 2 L * galaxies. These embedded coronae in hot clusters are generally smaller (1.5-4 kpc radii), less luminous ( < ∼ 10 41 erg s −1 ), and less massive (10 6.5 -10 8 M ⊙ ) than coronae in poor environments, demonstrating the negative effects of hot cluster environments on galactic coronae. Nevertheless, these coronae still manage to survive ICM stripping, evaporation, rapid cooling, and powerful AGN outflows, making them a rich source of information about gas stripping, microscopic transport, and feedback processes in the cluster environment. Heat conduction across the boundary of the coronae has to be suppressed by a factor of > ∼ 100, which implies the X-ray gas in early-type galaxies is magnetized and the magnetic field plays an important role in energy transfer. Stripping through transport processes (viscosity or turbulence) also needs to be suppressed by at least a factor of ten at the coronal boundary. The stellar mass loss inside the corona is key to maintaining the gas balance in coronae. The luminous, embedded coronae, with high central density (0.1 -0.4 cm −3 ), are mini-versions of group and cluster cooling cores. As the prevalence of coronae of massive galaxies implies a long lifetime ( > ∼ several Gyr), there must be a heat source inside coronae to offset cooling. While we argue that AGN heating may not generally be the heat source, we conclude that SN heating can be enough as long as the kinetic energy of SNe can be efficiently dissipated. We have also observed a connection between radiative cooling and the SMBH activity of their host galaxies as many coronae are associated with powerful radio galaxies. Cooling of the coronal gas may provide fuel for the central SMBH and nuclear star formation in environments where the amount of galactic cold gas is otherwise at a minimum. Diffuse thermal coronae have also been detected in at least 8 of 22 late-type (Sb or later) galaxies in our sample. Evidence for enhanced star formation triggered by the ICM pressure has been found in four late-type galaxies. The fraction of luminous X-ray AGN (> 10 41 ergs s −1 ) is not small (∼ 5%) in our sample.
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