Letter to the Editor

First detection of the Sunyaev Zel'dovich effect increment at λ < 650 μm ^*

¹ California Institute of Technology, Pasadena, CA 91125, USA e-mail: zemcov@caltech.edu
² Jet Propulsion Laboratory, Pasadena, CA 91109, USA
³ Steward Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721, USA
⁴ Herschel Science Centre, ESAC, ESA, PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain
⁵ Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 Av. Edouard Belin, 31400 Toulouse, France
⁶ Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France
⁷ Laboratoire d'Astrophysique de Marseille, CNRS – Université Aix-Marseille, 38 rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France
⁸ Geneva Observatory, University of Geneva, 51, Ch. des Maillettes, 1290 Versoix, Switzerland
⁹ NASA Herschel Science Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125, USA
¹⁰ UK Astronomy Technology Centre, Science and Technology Facilities Council, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
¹¹ Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹² Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
¹³ Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹⁴ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
¹⁵ Department of Astronomy, University of Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
¹⁶ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
¹⁷ Sterrewacht Leiden, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

Received: 31 March 2010
Accepted: 10 May 2010

Abstract

The Sunyaev-Zel'dovich (SZ) effect is a spectral distortion of the cosmic microwave background as observed through the hot plasma in galaxy clusters. This distortion is a decrement in the CMB intensity for λ > 1.3 mm, an increment at shorter wavelengths, and small again by λ ~ 250 μm. As part of the Herschel Lensing Survey (HLS) we have mapped 1E0657–56 (the Bullet cluster) with SPIRE with bands centered at 250, 350 and 500 μm and have detected the SZ effect at the two longest wavelengths. The measured SZ effect increment central intensities are ΔI₀ = 0.097 ± 0.019 MJy sr^-1 at 350 μm and ΔI₀ = 0.268 ± 0.031 MJy sr^-1 at 500 μm, consistent with the SZ effect spectrum derived from previous measurements at 2 mm. No other diffuse emission is detected. The presence of the finite temperature SZ effect correction is preferred by the SPIRE data at a significance of 2.1σ, opening the possibility that the relativistic SZ effect correction can be constrained by SPIRE in a sample of clusters. The results presented here have important ramifications for both sub-mm measurements of galaxy clusters and blank field surveys with SPIRE.