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ABSTRACT We present new Chandra X-ray observations of the brightest cluster galaxy (BCG) in the cool-core cluster Abell 2597 ( z= 0.0821). The data reveal an extensive kpc-scale X-ray cavity network as well as a 15-kpc filament of soft-excess gas exhibiting strong spatial correlation with archival Very Large Array radio data. In addition to several possible scenarios, multiwavelength evidence may suggest that the filament is associated with multiphase (103-107 K) gas that has been entrained and dredged-up by the propagating radio source. Stemming from a full spectral analysis, we also present profiles and 2D spectral maps of modelled X-ray temperature, entropy, pressure and metal abundance. The maps reveal an arc of hot gas which in projection borders the inner edge of a large X-ray cavity. Although limited by strong caveats, we suggest that the hot arc may be (a) due to a compressed rim of cold gas pushed outwards by the radio bubble or (b) morphologically and energetically consistent with cavity-driven active galactic nucleus heating models invoked to quench cooling flows, in which the enthalpy of a buoyant X-ray cavity is locally thermalized as ambient gas rushes to refill its wake. If confirmed, this would be the first observational evidence for this model. [ABSTRACT FROM AUTHOR]

ABSTRACT New Chandra X-ray and Herschel Far-Infrared (FIR) observations enable a multiwavelength study of active galactic nucleus (AGN) heating and intracluster medium (ICM) cooling in the brightest cluster galaxy (BCG) of Abell 2597 ( z= 0.0821). The new Chandra observations reveal the central ≲30 kpc X-ray cavity network to be more extensive than previously thought, and associated with enough enthalpy to theoretically inhibit the inferred classical cooling flow. Nevertheless, we present new evidence, consistent with previous results, that a moderately strong residual cooling flow is persisting at 4-8 per cent of the classically predicted rates in a spatially structured manner amid the feedback-driven excavation of the X-ray cavity network. New Herschel observations are used to estimate warm and cold dust masses, a lower limit gas-to-dust ratio and a star formation rate consistent with previous measurements. [O i] and CO(2−1) line profiles are used to constrain the kinematics of the ∼109 M⊙ reservoir of cold molecular gas. The cooling time profile of the ambient X-ray atmosphere is used to map the locations of the observational star formation entropy threshold as well as the theoretical thermal instability threshold. Both lie just outside the ≲30-kpc central region permeated by X-ray cavities, and star formation as well as ionized and molecular gas lie interior to both. The young stars are distributed in an elongated region that is aligned with the radio lobes, and their estimated ages are both younger and older than the X-ray cavity network, suggesting both jet-triggered as well as persistent star formation over the current AGN feedback episode. Bright X-ray knots that are coincident with extended Lyα and far-ultraviolet continuum filaments motivate a discussion of structured cooling from the ambient hot atmosphere along a projected axis that is perpendicular to X-ray cavity and radio axis. We conclude that the cooling ICM is the dominant contributor of the cold gas reservoir fuelling star formation and AGN activity in the Abell 2597 BCG. [ABSTRACT FROM AUTHOR]

We exploit the gravitational potential of a massive, rich cluster at to study the internal properties of a gravitationally lensed galaxy at . Using high-resolution Hubble Space Telescope imaging together with optical (VIMOS) and near-infrared (SINFONI) integral field spectroscopy, we have studied the rest-frame ultraviolet and optical properties of the lensed galaxy seen through the cluster RCS0224−002. Using a detailed gravitational lens model of the cluster, we reconstruct the source-frame morphology on 200 pc scales and find an Lyman-break galaxy with an intrinsic size of only , a velocity gradient of and an implied dynamical mass of within 2 kpc. We infer an integrated star formation rate of just from the intrinsic [O ii]λ3727 emission-line flux. The Lyα emission appears redshifted by with respect to the [O ii] emission. The Lyα is also significantly more extended than the nebular emission, extending over 11.9 × 2.4 kpc. Over this area, the Lyα centroid varies by less than . We model the asymmetric Lyα emission with an underlying Gaussian profile with an absorber in the blue wing and find that the underlying Lyα emission-line centroid is in excellent agreement with the [O ii] emission-line redshift. By examining the spatially resolved structure of the [O ii] and Lyα emission lines, we investigate the nature of this system. The model for local starburst galaxies suggested by Mas-Hesse et al. provides a good description of our data, and suggests that the galaxy is surrounded by a galactic-scale bipolar outflow which has recently bursted out of the system. The outflow, which appears to be currently located ≳30 kpc from the galaxy, is escaping at a speed of upto . Although the mass of the outflow is uncertain, the geometry and velocity of the outflow suggests that the ejected material is travelling far faster than escape velocity and will travel more than 1 Mpc (comoving) before eventually stalling. [ABSTRACT FROM AUTHOR]