Radio sources toward galaxy clusters at 30 GHz

K. Coble, M. Bonamente, J. E. Carlstrom, K. Dawson, N. Hasler, W. Holzapfel, M. Joy, S. LaRoque, D. P. Marrone, E. D. Reese

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


Extragalactic radio sources are a significant contaminant in cosmic microwave background and Sunyaev-Zel'dovich effect experiments. Deep interferometric observations with the BIMA and OVRO arrays are used to characterize the spatial, spectral, and flux distributions of radio sources toward massive galaxy clusters at 28.5 GHz. We compute counts of millijansky source fluxes from 89 fields centered on known massive galaxy clusters and 8 noncluster fields. We find that source counts in the inner regions of the cluster fields (within 0,5′ of the cluster center) are a factor of 8.9-2.8 +4.3 times higher than counts in the outer regions of the cluster fields (radius greater than 0.5′). Counts in the outer regions of the cluster fields are, in turn, a factor of 3.3-1.8 +4.1 greater than those in the noncluster fields. Counts in the noncluster fields are consistent with extrapolations from the results of other surveys. We compute the spectral indices of millijansky sources in the cluster fields between 1.4 and 28.5 GHz and find a mean spectral index of α = 0.66 with an rms dispersion of 0.36, where flux S ∝ V. The distribution is skewed, with a median spectral index of 0.72 and 25th and 75th percentiles of 0.51 and 0.92, respectively. This is steeper than the spectral indices of stronger field sources measured by other surveys.

Original languageEnglish (US)
Pages (from-to)897-905
Number of pages9
JournalAstronomical Journal
Issue number3
StatePublished - Sep 2007


  • Cosmic microwave background
  • Cosmology: observations
  • Galaxies: clusters: General
  • Radio continuum: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Radio sources toward galaxy clusters at 30 GHz'. Together they form a unique fingerprint.

Cite this