2021/01/10 by Michael D. Smith andJustin Donohoe, Donohoe, Michael D. Smith andJustin
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2101.03517
openalex publication_date 2021/01/10 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
Vast cavities in the intergalactic medium are excavated by radio galaxies.\nThe cavities appear as such in X-ray images because the external medium has\nbeen swept up, leaving a hot but low density bubble surrounding the radio\nlobes. We explore here the predicted thermal X-ray emission from a large set of\nhigh-resolution three dimensional simulations of radio galaxies driven by\nsupersonic jets. We assume adiabatic non-relativistic hydrodynamics with\ninjected straight and precessing jets of supersonic gas emitted from nozzles.\nImages of X-ray Bremsstrahlung emission tend to generate oval cavities in the\nsoft keV bands and leading arcuate structures in hard X-rays. However, the\ncavity shape is sensitive to the jet-ambient density contrast, varying from\nconcave-shaped at \η = 0.1 to convex for \η = 0.0001 where \η is\nthe jet/ambient density ratio.\n We find lateral ribs in the soft X-rays in certain cases and propose this as\nan explanation for those detected in the vicinity of Cygnus ,A. In bi-lobed or\nX-shaped sources and in curved or deflected jets, the strongest X-ray emission\nis not associated with the hotspot but with the relic lobe or deflection\nlocation. This is because the hot high-pressure and dense high-compression\nregions do not coincide. Directed toward the observer, the cavity becomes a\ndeep round hole surrounded by circular ripples. With short radio-mode outbursts\nwith a duty cycle of 10 % , the intracluster medium simmers with low Mach\nnumber shocks widely dissipating the jet energy in between active jet episodes.\n