The X-ray ribs within the cocoon shock of Cygnus A

R. T. Duffy; D. M. Worrall; M. Birkinshaw; P. E. J. Nulsen; M. W. Wise; M.N. de Vries; B. Snios; W. G. Mathews; R. A. Perley; M. J. Hardcastle; D. A. Rafferty; B. R. McNamara; A. C. Edge; J.P. McKean; C. L. Carilli; J. H. Croston; L. E. H. Godfrey; R. A. Laing

doi:10.1093/mnras/sty549

The X-ray ribs within the cocoon shock of Cygnus A

R. T. Duffy, D. M. Worrall, M. Birkinshaw, P. E. J. Nulsen, M. W. Wise, M.N. de Vries, B. Snios, W. G. Mathews, R. A. Perley, M. J. Hardcastle, D. A. Rafferty, B. R. McNamara, A. C. Edge, J.P. McKean, C. L. Carilli, J. H. Croston, L. E. H. Godfrey, R. A. Laing

Astronomy

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Abstract

We use new and archival Chandra observations of Cygnus A, totalling ∼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 × 1010 M⊙. 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.

Original language	English
Pages (from-to)	4848-4860
Number of pages	13
Journal	Monthly Notices of the Royal Astronomical Society
Volume	476
Issue number	4
DOIs	https://doi.org/10.1093/mnras/sty549
Publication status	Published - 1-Jun-2018

Keywords

galaxies: active, galaxies: individual: Cygnus A, radio continuum: galaxies, X-rays: galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies

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Duffy, R. T., Worrall, D. M., Birkinshaw, M., Nulsen, P. E. J., Wise, M. W., de Vries, M. N., Snios, B., Mathews, W. G., Perley, R. A., Hardcastle, M. J., Rafferty, D. A., McNamara, B. R., Edge, A. C., McKean, J. P., Carilli, C. L., Croston, J. H., Godfrey, L. E. H., & Laing, R. A. (2018). The X-ray ribs within the cocoon shock of Cygnus A. Monthly Notices of the Royal Astronomical Society, 476(4), 4848-4860. https://doi.org/10.1093/mnras/sty549

@article{d07cb9a8c6d64512a36ab2d6420193b1,

title = "The X-ray ribs within the cocoon shock of Cygnus A",

abstract = "We use new and archival Chandra observations of Cygnus A, totalling ∼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 × 1010 M⊙. 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.",

keywords = "galaxies: active, galaxies: individual: Cygnus A, radio continuum: galaxies, X-rays: galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies",

author = "Duffy, {R. T.} and Worrall, {D. M.} and M. Birkinshaw and Nulsen, {P. E. J.} and Wise, {M. W.} and {de Vries}, M.N. and B. Snios and Mathews, {W. G.} and Perley, {R. A.} and Hardcastle, {M. J.} and Rafferty, {D. A.} and McNamara, {B. R.} and Edge, {A. C.} and J.P. McKean and Carilli, {C. L.} and Croston, {J. H.} and Godfrey, {L. E. H.} and Laing, {R. A.}",

year = "2018",

month = jun,

day = "1",

doi = "10.1093/mnras/sty549",

language = "English",

volume = "476",

pages = "4848--4860",

journal = "Monthly Notices of the Royal Astronomical Society",

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Duffy, RT, Worrall, DM, Birkinshaw, M, Nulsen, PEJ, Wise, MW, de Vries, MN, Snios, B, Mathews, WG, Perley, RA, Hardcastle, MJ, Rafferty, DA, McNamara, BR, Edge, AC, McKean, JP, Carilli, CL, Croston, JH, Godfrey, LEH & Laing, RA 2018, 'The X-ray ribs within the cocoon shock of Cygnus A', Monthly Notices of the Royal Astronomical Society, vol. 476, no. 4, pp. 4848-4860. https://doi.org/10.1093/mnras/sty549

TY - JOUR

T1 - The X-ray ribs within the cocoon shock of Cygnus A

AU - Duffy, R. T.

AU - Worrall, D. M.

AU - Birkinshaw, M.

AU - Nulsen, P. E. J.

AU - Wise, M. W.

AU - de Vries, M.N.

AU - Snios, B.

AU - Mathews, W. G.

AU - Perley, R. A.

AU - Hardcastle, M. J.

AU - Rafferty, D. A.

AU - McNamara, B. R.

AU - Edge, A. C.

AU - McKean, J.P.

AU - Carilli, C. L.

AU - Croston, J. H.

AU - Godfrey, L. E. H.

AU - Laing, R. A.

PY - 2018/6/1

Y1 - 2018/6/1

N2 - We use new and archival Chandra observations of Cygnus A, totalling ∼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 × 1010 M⊙. 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.

AB - We use new and archival Chandra observations of Cygnus A, totalling ∼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 × 1010 M⊙. 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.

KW - galaxies: active, galaxies: individual: Cygnus A, radio continuum: galaxies, X-rays: galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies

U2 - 10.1093/mnras/sty549

DO - 10.1093/mnras/sty549

M3 - Article

SN - 0035-8711

VL - 476

SP - 4848

EP - 4860

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

The X-ray ribs within the cocoon shock of Cygnus A

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