†Present address: Physics Department, Stanford University, CA 94305-4060, USA.
Detection of a cosmic microwave background decrement towards a cluster of mJy radio sources
Article first published online: 4 APR 2002
Monthly Notices of the Royal Astronomical Society
Volume 331, Issue 1, pages 1–6, March 2002
How to Cite
Cotter, G., Buttery, H. J., Rawlings, S., Croft, S., Hill, G. J., Gay, P., Das, R., Drory, N., Grainge, K., Grainger, W. F., Jones, M. E., Pooley, G. G. and Saunders, R. (2002), Detection of a cosmic microwave background decrement towards a cluster of mJy radio sources. Monthly Notices of the Royal Astronomical Society, 331: 1–6. doi: 10.1046/j.1365-8711.2002.04996.x
- Issue published online: 4 APR 2002
- Article first published online: 4 APR 2002
- Accepted 2001 September 4. Received 2001 August 22; in original form 2001 March 7
- galaxies: active;
- galaxies: clusters: general;
- cosmic microwave background;
- cosmology: observations
We present the results of radio, optical and near-infrared observations of the field of TOC J0233.3+3021, a cluster of milliJansky radio sources from the TexOx Cluster survey. In an observation of this field with the Ryle Telescope (RT) at 15 GHz, we measure a decrement in the cosmic microwave background (CMB) of -675±95 μJy on the RT's≈0.65 kλ baseline. Using optical and infrared imaging with the McDonald 2.7-m Smith Reflector, the Calar Alto 3.5-m telescope and the United Kingdom Infrared Telescope (UKIRT), we identify the host galaxies of five of the radio sources and measure magnitudes of R≈24, J≈20, K≈18.
The cosmic microwave background (CMB) decrement is consistent with the Sunyaev–Zel'dovich (SZ) effect of a massive cluster of galaxies, which if modelled as a spherical King profile of core radius θC=20 arcsec has a central temperature decrement of 900 μK. The magnitudes and colours of the galaxies are consistent with those of old ellipticals at z∼1. We therefore conclude that TOC J0233.3+3021 is a massive, high redshift cluster. These observations add to the growing evidence for a significant population of massive clusters at high redshift, and demonstrate the effectiveness of combining searches for active galactic nuclei (AGN) ‘signposts’ to clusters with the redshift-independence of the SZ effect.