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The Voit et al. black hole feedback valve model predicts relationships between stellar velocity dispersion and atmospheric structure among massive early-type galaxies. In this work, we test that model using the Chandra archival sample of 49 early-type galaxies from Lakhchaura et al. We consider relationships between stellar velocity dispersion and entropy profile slope, multiphase gas extent, and the ratio of cooling time to freefall time. We also define subsamples based on data quality and entropy profile properties that clarify those relationships and enable more specific tests of the model predictions. We find that the atmospheric properties of early-type galaxies generally align with the predictions of the Voit et al. model, in that galaxies with a greater stellar velocity dispersion tend to have radial profiles of pressure, gas density, and entropy with steeper slopes and less extended multiphase gas. Quantitative agreement with the model predictions improves when the sample is restricted to have low central entropy and a stellar velocity dispersion of between 220 and 300 km s−1. [ABSTRACT FROM AUTHOR]

We present an archival analysis of Chandra X-ray observations for 12 nearby early-type galaxies hosting radio sources with radio power >1023 W Hz−1 at 1.4 GHz, similar to the radio power of the radio source in NGC 4261. Previously, in a similar analysis of eight nearby X-ray and optically bright elliptical galaxies, Werner et al. found that NGC 4261 exhibited unusually low central gas entropy compared to the full sample. In the central 0.3 kpc of NGC 4261, the ratio of cooling time to freefall time (tcool/tff) is less than 10, indicating that cold clouds may be precipitating out of the hot ambient medium and providing fuel for accretion in the central region. NGC 4261 also hosts the most powerful radio source in the original sample. Because NGC 4261 may represent an important phase during which powerful feedback from a central active galactic nucleus (AGN) is fueled by multiphase condensation in the central kiloparsec, we searched the Chandra archive for analogs to NGC 4261. We present entropy profiles of those galaxies, as well as profiles of tcool/tff. We find that one of them, IC 4296, exhibits properties similar to NGC 4261, including the presence of only single-phase gas outside of r ∼ 2 kpc and a similar central velocity dispersion. We compare the properties of NGC 4261 and IC 4296 to hydrodynamic simulations of AGN feedback fueled by precipitation. Over the course of those simulations, the single-phase galaxy has an entropy gradient that remains similar to the entropy profiles inferred from our observations. [ABSTRACT FROM AUTHOR]

We present a detailed study of a close pair of clusters of galaxies, A3532 and A3530, and their environments. The Chandra X-ray image of A3532 reveals the presence of substructures on scales of ~20" in its core. XMM-Newton maps of the clusters show excess X-ray emission from an overlapping region between them. Spectrally determined projected temperature and entropy maps do not show any signs of cluster scale mergers either in the overlapping region or in any of the clusters. In A3532, however, some signs of the presence of galaxy scale mergers are visible, e.g., anisotropic temperature variations in the projected thermodynamic maps, a wide-angle-tailed (WAT) radio source in the brighter nucleus of its dumbbell brightest cluster galaxy, and a candidate X-ray cavity coincident with the northwestern extension of theWAT source in the low-frequency radio observations. The northwestern extension in A3532 seems either a part of theWAT or an unrelated diffuse source in A3532 or in the background. There is an indication that the cool core in A3532 has been disrupted by the central activity of the galactic nucleus. A reanalysis of the redshift data reinforces the close proximity of the clusters. The excess emission in the overlapping region appears to be a result of tidal interactions as the two clusters approach each other for the first time. However, we cannot rule out the possibility of the excess being due to the chance superposition of their X-ray halos. [ABSTRACT FROM AUTHOR]

We present a detailed imaging and spectral analysis of the merging environment of the bimodal cluster A3395 using X-ray and radio observations. X-ray images of the cluster show five main constituents of diffuse emission: A3395 NE, A3395 SW, A3395 NW, A3395 W, and a filament connecting NE to W. X-ray surface brightness profiles of the cluster did not show any shock fronts in the cluster. Temperature and entropy maps show high-temperature and high-entropy regions in the W, the NW, the filament, and between the NE and SW subclusters. The NE, SW, and W components have X-ray bolometric luminosities similar to those of rich clusters of galaxies but have relatively higher temperatures. Similarly, the NW component has X-ray bolometric luminosity similar to that of isolated groups but with much higher temperature. It is, therefore, possible that all the components of the cluster have been heated by the ongoing mergers. The NE subcluster is the most massive and luminous constituent and other subclusters are found to be gravitationally bound to it. The W component is most probably either a clump of gas stripped off the SW due to ram pressure or a separate subcluster that has merged or is merging with the SW. No X-ray cavities are seen associated with the wide-angle-tailed (WAT) radio source neat the center of the SW subcluster. Minimum energy pressure in the radio emission peaks of the WAT galaxy is comparable with the external thermal pressure. The radio spectrum of the WAT suggests a spectral age of ~ 10 Myr. [ABSTRACT FROM AUTHOR]