The Atacama Cosmology Telescope: Dynamical masses for 44 SZ-selected galaxy clusters over 755 square degrees

Cristóbal Sifón, Nick Battaglia, Matthew Hasselfield, Felipe Menanteau, L. Felipe Barrientos, J. Richard Bond, Devin Crichton, Mark J. Devlin, Rolando Dünner, Matt Hilton, Adam D. Hincks, Renée Hlozek, Kevin M. Huffenberger, John P. Hughes, Leopoldo Infante, Arthur Kosowsky, Danica Marsden, Tobias A. Marriage, Kavilan Moodley, Michael D. NiemackLyman A. Page, David N. Spergel, Suzanne T. Staggs, Hy Trac, Edward J. Wollack

Research output: Contribution to journalArticlepeer-review


We present galaxy velocity dispersions and dynamical mass estimates for 44 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect by the Atacama Cosmology Telescope. Dynamical masses for 18 clusters are reported here for the first time. Using N-body simulations, we model the different observing strategies used to measure the velocity dispersions and account for systematic effects resulting from these strategies. We find that the galaxy velocity distributions may be treated as isotropic, and that an aperture correction of up to 7 per cent in the velocity dispersion is required if the spectroscopic galaxy sample is sufficiently concentrated towards the cluster centre. Accounting for the radial profile of the velocity dispersion in simulations enables consistent dynamical mass estimates regardless of the observing strategy. Cluster masses M200 are in the range (1-15) × 1014M. Comparing with masses estimated from the SZ distortion assuming a gas pressure profile derived from X-ray observations gives a mean SZ-to-dynamical mass ratio of 1.10 ± 0.13, but there is an additional 0.14 systematic uncertainty due to the unknown velocity bias; the statistical uncertainty is dominated by the scatter in the mass-velocity dispersion scaling relation. This ratio is consistent with previous determinations at these mass scales.

Original languageEnglish (US)
Pages (from-to)248-270
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Sep 1 2016


  • Cosmology: observations
  • Galaxies: clusters: general
  • Galaxies: distances and redshifts
  • Large-scale structure of Universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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