AMiBA: CLUSTER SUNYAEV–ZEL’DOVICH EFFECT OBSERVATIONS WITH THE EXPANDED 13-ELEMENT ARRAY

Abstract

This is the final published version of the article (version of record). It first appeared online via Institute of Physics at http://iopscience.iop.org/article/10.3847/0004-637X/830/2/91/meta. Please refer to any applicable terms of use of the publisher. University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. ABSTRACTThe Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is a co-planar interferometer array operating at a wavelength of 3 mm to measure the Sunyaev-Zel'dovich effect (SZE) of galaxy clusters at arcminute scales. The first phase of operation-with a compact 7-element array with 0.6 m antennas (AMiBA-7)-observed six clusters at angular scales from ¢ 5 to ¢ 23 . Here, we describe the expansion of AMiBA to a 13-element array with 1.2 m antennas (AMiBA-13), its subsequent commissioning, and cluster SZE observing program. The most noticeable changes compared to AMiBA-7 are (1) array re-configuration with baselines ranging from 1.4 m to 4.8 m, allowing us to sample structures between ¢ 2 and ¢ 10 , (2) 13 new lightweight carbon-fiber-reinforced plastic (CFRP) 1.2 m reflectors, and (3) additional correlators and six new receivers. Since the reflectors are co-mounted on and distributed over the entire six-meter CFRP platform, a refined hexapod pointing error model and phase error correction scheme have been developed for AMiBA-13. These effects-entirely negligible for the earlier central close-packed AMiBA-7 configuration-can lead to additional geometrical delays during observations. Our correction scheme recovers at least 80±5% of thepoint-source fluxes. We, therefore, apply an upward correcting factor of 1.25 to our visibilities to correct for phase decoherence, and a±5% systematic uncertainty is added in quadrature with our statistical errors. We demonstrate the absence of further systematics with a noise level consistent with zero in stacked uv-visibilities. From the AMiBA-13 SZE observing program, we present here maps of a subset of 12 clusters with signal-to-noise ratios above five. We demonstrate combining AMiBA-7 with AMiBA-13 observations on Abell 1689, by jointly fitting their data to a generalized Navarro-Frenk-White model. Our cylindrically integrated Compton-y values for five radii are consistent with results from the Berkeley-IllinoisMaryland Array, the Owens Valley Radio Observatory, the Sunyaev-Zel'dovich Array, and the Planck Observatory. We also report the first targeted SZE detection toward the optically selected cluster RCS J1447 +0828, and we demonstrate the ability of AMiBA SZE data to serve as a proxy for the total cluster mass. Finally, we show that our AMiBA-SZE derived cluster masses are consistent with recent lensing mass measurements in the literature.

The comptonization parameter from simulations of single-frequency, single-dish, dual-beam, cm-wave observations of galaxy clusters and mitigating CMB confusion using the Planck sky survey

“…Over the past several years many dedicated experiments have been used to detect the Sunyaev-Zel'dovich (SZ) effect [33] from galaxy clusters at radio wavelengths [e.g., Berkeley-Illinois-Maryland Association (BIMA) [7]; Combined Array for Research in Millimeter-wave Astronomy (CARMA) [19,22]; the South Pole Telescope (SPT) [31]; the Néel IRAM KIDs Array (NIKA) [1]; the Atacama Pathfinder EXperiment Sunyaev-Zel'dovich Instrument (APEX-SZ) [2,9]; the Arcminute Microkelvin Imager (AMI) [32,35]; Planck Surveyor [30]; the Atacama Cosmology Telescope (ACT) [11]; Array for Microwave Background Anisotropy (AMiBA) [18]]. Within the next few years, new observational facilities will become operational and will search for galaxy clusters, complementing the galaxy cluster census across the Universe [e.g., New IRAM KID Array 2 (NIKA2) on the Institut de Radio Astronomie Millimetrique 30 m telescope [6]].…”