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A high signal-to-noise ratio map of the Sunyaev–Zel’dovich increment at 1.1-mm wavelength in Abell 1835




We present an analysis of an 8-arcmin diameter map of the area around the galaxy cluster Abell 1835 from jiggle-map observations at a wavelength of 1.1 mm using the Bolometric Camera (Bolocam) mounted on the Caltech Submillimeter Observatory (CSO). The data are well described by a model including a extended Sunyaev–Zel’dovich (SZ) emission from the cluster gas plus emission from the cluster central galaxy and two bright background submm galaxies magnified by the gravitational lensing of the cluster. We measure flux densities of the two bright point sources in the field: SMM J14011+0252 and SMM J14009+0252 to be 6.5 ± 2.0 ± 0.8 and 11.3 ± 1.9 ± 1.3 mJy, respectively. Fitting the map to a sky model consisting of the point sources and the SZ emission from the cluster gas with a beta model density profile with parameters, θc= 33.6 arcsec and β= 0.69, we find the peak surface brightness of the SZ emission to be Ic= 3.73 ± 0.45 ± 0.60 × 10−21 W m−2sr−1 Hz−1, where the first error is the statistical uncertainty in the fit and the second error represents the calibration uncertainty and additional systematics. Assuming zero cluster peculiar velocity and an X-ray temperature of Te= 9 keV, this surface brightness corresponds to a central Comptonization of y0= (4.41 ± 0.53 ± 0.70) × 10−4. The cluster image represents one of the highest significance SZ detections of a cluster in the positive region of the thermal SZ spectrum to date. We compare the measured central intensity at 1.1 mm to other SZ measurements of Abell 1835 at different wavelengths to obtain values for y0= (3.58 ± 0.28) × 10−4 and the cluster peculiar velocity vz=−538 ± 414 km s−1.