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ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745-191

Russell, H.R.; McNamara, B.R.; Fabian, A.C.; Nulsen, P.E.J.; Edge, A.C.; Combes, F.; Murray, N.W.; Parrish, I.J.; Salomé, P.; Sanders, J.S.; Baum, S.A.; Donahue, M.; Main, R.A.; O'Connell, R.W.; O'Dea, C.P.; Oonk, J.B.R.; Tremblay, G.; Vantyghem, A.N.; Voit, G.M.

ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745-191 Thumbnail


H.R. Russell

B.R. McNamara

A.C. Fabian

P.E.J. Nulsen

F. Combes

N.W. Murray

I.J. Parrish

P. Salomé

J.S. Sanders

S.A. Baum

M. Donahue

R.A. Main

R.W. O'Connell

C.P. O'Dea

J.B.R. Oonk

G. Tremblay

A.N. Vantyghem

G.M. Voit


We present ALMA observations of the CO(1-0) and CO(3-2) line emission tracing filaments of cold molecular gas in the central galaxy of the cluster PKS 0745-191. The total molecular gas mass of 4.6 ± 0.3 × 109 M⊙, assuming a Galactic XCO factor, is divided roughly equally between three filaments each extending radially 3–5 kpc from the galaxy centre. The emission peak is located in the SE filament ∼ 1 arcsec (2 kpc) from the nucleus. The velocities of the molecular clouds in the filaments are low, lying within ± 100 km s−1 of the galaxy's systemic velocity. Their FWHMs are less than 150 km s−1, which is significantly below the stellar velocity dispersion. Although the molecular mass of each filament is comparable to a rich spiral galaxy, such low velocities show that the filaments are transient and the clouds would disperse on <107 yr timescales unless supported, likely by the indirect effect of magnetic fields. The velocity structure is inconsistent with a merger origin or gravitational free-fall of cooling gas in this massive central galaxy. If the molecular clouds originated in gas cooling even a few kpc from their current locations their velocities would exceed those observed. Instead, the projection of the N and SE filaments underneath X-ray cavities suggests they formed in the updraft behind bubbles buoyantly rising through the cluster atmosphere. Direct uplift of the dense gas by the radio bubbles appears to require an implausibly high coupling efficiency. The filaments are coincident with low temperature X-ray gas, bright optical line emission and dust lanes indicating that the molecular gas could have formed from lifted warmer gas that cooled in situ.


Russell, H., McNamara, B., Fabian, A., Nulsen, P., Edge, A., Combes, F., …Voit, G. (2016). ALMA observations of cold molecular gas filaments trailing rising radio bubbles in PKS 0745-191. Monthly Notices of the Royal Astronomical Society, 458(3), 3134-3149.

Journal Article Type Article
Acceptance Date Feb 18, 2016
Online Publication Date Feb 22, 2016
Publication Date May 21, 2016
Deposit Date Mar 16, 2016
Publicly Available Date Mar 17, 2016
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 458
Issue 3
Pages 3134-3149
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Published Journal Article (Advance online version) (5.1 Mb)

Copyright Statement
Advance online version This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Published Journal Article (Final published version) (3.6 Mb)

Copyright Statement
Final published version

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