The Multi-Epoch Jet Outbursts in Abell 496: synchrotron ageing and buoyant X-ray cavities draped by warm gas filaments

Abstract

The galaxy cluster Abell 496 has been extensively studied in the past for the clear sloshing motion of the hot gas on large scales, but the interplay between the central radio galaxy and the surrounding cluster atmosphere is mostly unexplored. We present a dedicated radio, X-ray, and optical study of Abell 496 aimed at investigating this connection. We use deep radio images obtained with the Giant Metrewave Radio Telescope at 150, 330 and 617 MHz, Very Large Array at 1.4 and 4.8 GHz, and VLA Low Band Ionosphere and Transient Experiment at 340 MHz, with angular resolutions ranging from 0.''5 to 25''. Additionally, we use archival Chandra and Very Large Telescope MUSE observations. The radio images reveal three distinct periods of jet activity: an ongoing episode on sub-kpc scales with an inverted radio spectrum; an older episode that produced lobes on scales $\sim$20 kpc which now have a steep spectral index ($\alpha =2.0\pm 0.1$); and an oldest episode that produced lobes on scales of $\sim$50 - 100 kpc with an ultra-steep spectrum ($\alpha =2.7\pm 0.2$). Archival Chandra X-ray observations show that the older and oldest episodes have excavated two generations of cavities in the hot gas of the cluster. The outermost X-ray cavity has a clear mushroom-head shape, likely caused by its buoyant rise in the cluster's potential. Cooling of the hot gas is ongoing in the innermost 20 kpc, where H$\alpha$-bright warm filaments are visible in VLT-MUSE data. The H$\alpha$-filaments are stretched towards the mushroom-head cavity, which may have stimulated ICM cooling in its wake. We conclude by commenting on the non-detection of a radio mini-halo in this vigorously sloshing, but low-mass, galaxy cluster.

Accepted for publication in Astronomy & Astrophysics

References in corpus (25)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Heating Hot Atmospheres with Active Galactic Nuclei
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• DiFX: A software correlator for very long baseline interferometry using multi-processor computing environments
• The origin of cold fronts in the cores of relaxed galaxy clusters
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• The Rapid ASKAP Continuum Survey I: Design and First Results
• Radio galaxies and feedback from AGN jets
• The Very Large Array Low-frequency Sky Survey Redux (VLSSr)
• Compact steep-spectrum and peaked-spectrum radio sources
• The Rapid ASKAP Continuum Survey Paper II: First Stokes I Source Catalogue Data Release
• Cooling Time, Freefall Time, and Precipitation in the Cores of ACCEPT Galaxy Clusters
• Physical viscosity in smoothed particle hydrodynamics simulations of galaxy clusters
• Hot gaseous atmospheres in galaxy groups and clusters are both heated and cooled by X-ray cavities
• Recent Progress in Modeling the Macro- and Micro-Physics of Radio Jet Feedback in Galaxy Clusters
• On the relation between mini-halos and AGN feedback in clusters of galaxies
• Metal distribution in sloshing galaxy clusters: the case of A496
• Different Methods of Forming Cold Fronts in Non-Merging Clusters
• The deepest $Chandra$ view of RBS 797: evidence for two pairs of equidistant X-ray cavities
• Bubble-driven Gas Uplift in Galaxy Clusters and its Velocity Features
• Buoyant Bubbles in a Cooling Intracluster Medium I. Hydrodynamic Bubbles
• Selecting and Modelling Remnant AGNs with Limited Spectral Coverage
• High-Spectral Resolution Observations of the Optical Filamentary Nebula in NGC 1275

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