A 13 CO Detection in a Brightest Cluster Galaxy
| Autor: | Alastair C. Edge, P. Salomé, M. T. Hogan, Francoise Combes, Andrew C. Fabian, Paul Nulsen, A. N. Vantyghem, Helen Russell, Brian R. McNamara, Michael McDonald |
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| Přispěvatelé: | Department of Physics, University of Wales, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Galaxies et cosmologie, Collège de France (CdF (institution)), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), École normale supérieure - Paris (ENS Paris), Chaire Galaxies et cosmologie |
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Physics
[PHYS]Physics [physics] 010308 nuclear & particles physics FOS: Physical sciences Astronomy Astronomy and Astrophysics Space (mathematics) Astrophysics - Astrophysics of Galaxies 01 natural sciences 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Brightest cluster galaxy [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] 010303 astronomy & astrophysics ComputingMilieux_MISCELLANEOUS |
| Zdroj: | The Astrophysical Journal The Astrophysical Journal, 2017, 848 (2), pp.101. ⟨10.3847/1538-4357/aa8fd0⟩ The Astrophysical Journal, American Astronomical Society, 2017, 848 (2), pp.101. ⟨10.3847/1538-4357/aa8fd0⟩ Astrophysical journal, 2017, Vol.848(2), pp.101 [Peer Reviewed Journal] |
| ISSN: | 0004-637X 1538-4357 |
| Popis: | We present ALMA Cycle 4 observations of CO(1-0), CO(3-2), and $^{13}$CO(3-2) line emission in the brightest cluster galaxy of RXJ0821+0752. This is one of the first detections of $^{13}$CO line emission in a galaxy cluster. Half of the CO(3-2) line emission originates from two clumps of molecular gas that are spatially offset from the galactic center. These clumps are surrounded by diffuse emission that extends $8~{\rm kpc}$ in length. The detected $^{13}$CO emission is confined entirely to the two bright clumps, with any emission outside of this region lying below our detection threshold. Two distinct velocity components with similar integrated fluxes are detected in the $^{12}$CO spectra. The narrower component ($60~{\rm km}~{\rm s}^{-1}$ FWHM) is consistent in both velocity centroid and linewidth with $^{13}$CO(3-2) emission, while the broader ($130-160~{\rm km}~{\rm s}^{-1}$), slightly blueshifted wing has no associated $^{13}$CO(3-2) emission. A simple local thermodynamic model indicates that the $^{13}$CO emission traces $2.1\times 10^{9}~{\rm M}_\odot$ of molecular gas. Isolating the $^{12}$CO velocity component that accompanies the $^{13}$CO emission yields a CO-to-H$_2$ conversion factor of $\alpha_{\rm CO}=2.3~{\rm M}_{\odot}~({\rm K~km~s^{-1}})^{-1}$, which is a factor of two lower than the Galactic value. Adopting the Galactic CO-to-H$_2$ conversion factor in brightest cluster galaxies may therefore overestimate their molecular gas masses by a factor of two. This is within the object-to-object scatter from extragalactic sources, so calibrations in a larger sample of clusters are necessary in order to confirm a sub-Galactic conversion factor. Comment: 11 pages, 5 figures, accepted by ApJ |
| Databáze: | OpenAIRE |
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