1. The X-ray ribs within the cocoon shock of Cygnus A
- Author
-
Alastair C. Edge, Bradford Snios, Michael W. Wise, William G. Mathews, Robert Laing, Martin J. Hardcastle, Paul Nulsen, Ryan T. Duffy, M. N. de Vries, Leith Godfrey, Chris Carilli, D. Rafferty, Mark Birkinshaw, Judith H. Croston, Richard A. Perley, Brian R. McNamara, John McKean, Diana M Worrall, High Energy Astrophys. & Astropart. Phys (API, FNWI), and Sterrenkunde
- Subjects
active [Galaxies] ,Astrophysics::High Energy Astrophysical Phenomena ,galaxies: active ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,galaxies: individual: Cygnus A ,0103 physical sciences ,Cluster (physics) ,Cygnus A ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,radio continuum: galaxies ,Jet (fluid) ,Shock (fluid dynamics) ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Debris ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,galaxies [X-rays] ,Core (optical fiber) ,Temperature gradient ,X-rays: galaxies ,galaxies: active, galaxies: individual: Cygnus A, radio continuum: galaxies, X-rays: galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,individual: Cygnus A- radio continuum: galaxies [Galaxies] ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We use new and archival Chandra observations of Cygnus A, totalling $\sim$1.9 Ms, to investigate the distribution and temperature structure of gas lying within the projected extent of the cocoon shock and exhibiting a rib-like structure. We confirm that the X-rays are dominated by thermal emission with an average temperature of around 4 keV, and have discovered an asymmetry in the temperature gradient, with the southwestern part of the gas cooler than the rest by up to 2 keV. Pressure estimates suggest that the gas is a coherent structure of single origin located inside the cocoon, with a mass of roughly $2\times10^{10} M_{\odot}$. We conclude that the gas is debris resulting from disintegration of the cool core of the Cygnus A cluster after the passage of the jet during the early stages of the current epoch of activity. The 4 keV gas now lies on the central inside surface of the hotter cocoon rim. The temperature gradient could result from an offset between the centre of the cluster core and the Cygnus A host galaxy at the switch-on of current radio activity., 15 pages, 12 figures, accepted by MNRAS
- Published
- 2018