skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A {sup 13}CO Detection in a Brightest Cluster Galaxy

Abstract

We present ALMA Cycle 4 observations of CO(1-0), CO(3-2), and {sup 13}CO(3-2) line emission in the brightest cluster galaxy (BCG) of RXJ0821+0752. This is one of the first detections of {sup 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 kpc in length. The detected {sup 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 {sup 12}CO spectra. The narrower component (60 km s{sup −1} FWHM) is consistent in both velocity centroid and linewidth with {sup 13}CO(3-2) emission, while the broader (130–160 km s{sup −1}), slightly blueshifted wing has no associated {sup 13}CO(3-2) emission. A simple local thermodynamic model indicates that the {sup 13}CO emission traces 2.1 × 10{sup 9} M {sub ⊙} of molecular gas. Isolating the {sup 12}CO velocity component that accompanies the {sup 13}CO emission yields a CO-to-H{sub 2} conversion factor of α {sub CO} = 2.3 M {sub ⊙} (K km s{supmore » −1}){sup −1}, which is a factor of two lower than the Galactic value. Adopting the Galactic CO-to-H{sub 2} conversion factor in BCGs 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.« less

Authors:
; ;  [1];  [2]; ;  [3]; ;  [4];  [5];  [6]
  1. Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)
  2. Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)
  3. LERMA, Observatoire de Paris, CNRS, UPMC, PSL Univ., 61 avenue de l’Observatoire, F-75014 Paris (France)
  4. Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  5. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
  6. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22679739
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 848; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CALIBRATION; CARBON 12; CARBON 13; CARBON MONOXIDE; CONVERSION; DETECTION; EMISSION; GALAXIES; GALAXY CLUSTERS; HYDROGEN; LINE WIDTHS; MASS; SPECTRA; THERMODYNAMIC MODEL; THERMODYNAMICS

Citation Formats

Vantyghem, A. N., McNamara, B. R., Hogan, M. T., Edge, A. C., Combes, F., Salomé, P., Russell, H. R., Fabian, A. C., McDonald, M., and Nulsen, P. E. J., E-mail: a2vantyg@uwaterloo.ca. A {sup 13}CO Detection in a Brightest Cluster Galaxy. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8FD0.
Vantyghem, A. N., McNamara, B. R., Hogan, M. T., Edge, A. C., Combes, F., Salomé, P., Russell, H. R., Fabian, A. C., McDonald, M., & Nulsen, P. E. J., E-mail: a2vantyg@uwaterloo.ca. A {sup 13}CO Detection in a Brightest Cluster Galaxy. United States. doi:10.3847/1538-4357/AA8FD0.
Vantyghem, A. N., McNamara, B. R., Hogan, M. T., Edge, A. C., Combes, F., Salomé, P., Russell, H. R., Fabian, A. C., McDonald, M., and Nulsen, P. E. J., E-mail: a2vantyg@uwaterloo.ca. Fri . "A {sup 13}CO Detection in a Brightest Cluster Galaxy". United States. doi:10.3847/1538-4357/AA8FD0.
@article{osti_22679739,
title = {A {sup 13}CO Detection in a Brightest Cluster Galaxy},
author = {Vantyghem, A. N. and McNamara, B. R. and Hogan, M. T. and Edge, A. C. and Combes, F. and Salomé, P. and Russell, H. R. and Fabian, A. C. and McDonald, M. and Nulsen, P. E. J., E-mail: a2vantyg@uwaterloo.ca},
abstractNote = {We present ALMA Cycle 4 observations of CO(1-0), CO(3-2), and {sup 13}CO(3-2) line emission in the brightest cluster galaxy (BCG) of RXJ0821+0752. This is one of the first detections of {sup 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 kpc in length. The detected {sup 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 {sup 12}CO spectra. The narrower component (60 km s{sup −1} FWHM) is consistent in both velocity centroid and linewidth with {sup 13}CO(3-2) emission, while the broader (130–160 km s{sup −1}), slightly blueshifted wing has no associated {sup 13}CO(3-2) emission. A simple local thermodynamic model indicates that the {sup 13}CO emission traces 2.1 × 10{sup 9} M {sub ⊙} of molecular gas. Isolating the {sup 12}CO velocity component that accompanies the {sup 13}CO emission yields a CO-to-H{sub 2} conversion factor of α {sub CO} = 2.3 M {sub ⊙} (K km s{sup −1}){sup −1}, which is a factor of two lower than the Galactic value. Adopting the Galactic CO-to-H{sub 2} conversion factor in BCGs 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.},
doi = {10.3847/1538-4357/AA8FD0},
journal = {Astrophysical Journal},
number = 2,
volume = 848,
place = {United States},
year = {Fri Oct 20 00:00:00 EDT 2017},
month = {Fri Oct 20 00:00:00 EDT 2017}
}