2008/05/31 by Yen‐Ting Lin, Yen-Ting Lin, Bruce Partridge +9 · 2 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmic microwave background #Extrapolation #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Physics #Radio Astronomy Observations and Technology #Radio galaxy #Radio telescope #Redshift #South Pole Telescope #Spectral line #Sunyaev–Zel'dovich effect #Telescope #astro-ph
paper · pdf · doi:10.1088/0004-637x/694/2/992
published as Astrophys.J.694:992-1009,2009 · 16 pages, 10 figures, 5 tables; version published in ApJ; forecast for SZE surveys changed with respect to previous version
openalex publication_date 2009/03/20 · arxiv created 2009/04/04 · arxiv updated 2011/02/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
To explore the high-frequency radio spectra of galaxies in clusters, we used NRAO's Very Large Array at four frequencies, 4.9–43 GHz, to observe 139 galaxies in low redshift ( z < 0.25), X-ray detected, clusters. The clusters were selected from the survey conducted by Ledlow and Owen, who provided redshifts and 1.4 GHz flux densities for all the radio sources. We find that more than half of the observed sources have steep microwave spectra as generally expected (α < −0.5, in the convention S ∝ ν α ). However, 60%–70% of the unresolved or barely resolved sources have flat or inverted spectra. Most of these show an upward turn in flux at ν>22 GHz, implying a higher flux than would be expected from an extrapolation of the lower-frequency flux measurements. Our results quantify the need for careful source subtraction in increasingly sensitive measurements of the Sunyaev–Zel'dovich effect in clusters of galaxies (as currently being conducted by, for instance, the Atacama Cosmology Telescope and South Pole Telescope groups).