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

S. L. Hamer, A. C. Edge, A. M. Swinbank, 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

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


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 μmare detected. We estimate the mass of the cold gas within the disc to be Mgas=2.3±0.3×109M. 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.

Original languageEnglish
Article numberstt1949
Pages (from-to)862-878
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Dec 2013


  • Cd
  • Clusters
  • Elliptical and lenticular
  • Galaxies
  • Hydra-A-galaxies
  • Individual
  • Intraclustermedium-galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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