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Cold gas dynamics in Hydra-A: evidence for a rotating disc

Hamer, S.L.; Edge, A.C.; Swinbank, A.M.; Oonk, J.B.R.; Mittal, R.; McNamara, B.R.; Russell, H.R.; Bremer, M.N.; Combes, F.; Fabian, A.C.; Nesvadba, N.P.H.; O'Dea, C.P.; Baum, S.A.; Salomé, P.; Tremblay, G.; Donahue, M.; Ferland, G.J.; Sarazin, C.L.

Cold gas dynamics in Hydra-A: evidence for a rotating disc Thumbnail


S.L. Hamer

J.B.R. Oonk

R. Mittal

B.R. McNamara

H.R. Russell

M.N. Bremer

F. Combes

A.C. Fabian

N.P.H. Nesvadba

C.P. O'Dea

S.A. Baum

P. Salomé

G. Tremblay

M. Donahue

G.J. Ferland

C.L. Sarazin


We present multifrequency observations of the radio galaxy Hydra-A (3C218) located in the core of a massive, X-ray luminous galaxy cluster. Integral field unit spectroscopy is used to trace the kinematics of the ionized and warm molecular hydrogen which are consistent with an ∼5 kpc rotating disc. Broad, double-peaked lines of CO(2–1), [C II] 157 μm and [O I] 63 μm are detected. We estimate the mass of the cold gas within the disc to be Mgas = 2.3 ± 0.3 × 109 M⊙. These observations demonstrate that the complex line profiles found in the cold atomic and molecular gas are related to the rotating disc or ring of gas. Finally, a Hubble Space Telescope image of the galaxy shows that this gas disc contains a substantial mass of dust. The large gas mass, star formation rate and kinematics are consistent with the levels of gas cooling from the intracluster medium (ICM). We conclude that the cold gas originates from the continual quiescent accumulation of cooled ICM gas. The rotation is in a plane perpendicular to the projected orientation of the radio jets and ICM cavities hinting at a possible connection between the kpc-scale cooling gas and the accretion of material on to the black hole. We discuss the implications of these observations for models of cold accretion, AGN feedback and cooling flows.

Journal Article Type Article
Publication Date Jan 1, 2014
Deposit Date Apr 3, 2014
Publicly Available Date Jun 19, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 437
Issue 1
Pages 862-878
Keywords Galaxies: clusters: individual: Hydra-A, Galaxies: clusters: intracluster medium, Galaxies: elliptical and lenticular, cD
Public URL


Published Journal Article (3.5 Mb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2014 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.

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