AMiBA: Measuring Hot Gas Content of Galaxy Clusters via the Sunyaev-Zel'dovich Effect
Kai-yang Lin1*, Ming-Tang Chen1, Chih-Wei Locutus Huang1, Patrick M. Koch1, Yu-Wei Liao1, Guo-Chin Liu2, Hiroaki Nishioka1, Keiichi Umetsu1, Fu-Cheng Wang3, Jiun-Huei Proty Wu3,1
1Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
2Department of Physics, Tamkang University, Tamsui, Taiwan
3Department of Physics, National Taiwan University, Taipei, Taiwan
* presenting author:Kai-Yang Lin,
Baryons in galaxy clusters exist mostly in the form of ionized hot gas. The intra-cluster gas is heated by gravity and radiates in X-ray. The hot electrons also scatter the CMB photons and produce the Sunyaev-Zel'dovich (SZ) effect. A few SZ surveys have been carried out and showed that it is a powerful way of finding high-z massive clusters. Furthermore, the SZ effect conforms to a "universal" profile that is related to the hosting dark matter halo property.

The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is an arcminute-scale interferometer that operates at 3mm wavelength in Hawaii. During 2011-2014, we have used AMiBA to measure the SZ effect from more than 30 clusters. The targets formed three main categories: (1) CLASH sample: Multi-wavelength study of clusters using lensing, X-ray, and SZE; (2) AMiBA-7 sample: Better determination of gas profile by combining data from the shorter baseline AMiBA-7; (3) RCS2 sample: General gas property of optically selected clusters. At least 12 of the clusters were robustly detected at more than 5σ, and we are able to determine the amount of hot gas as well as dark matter in those clusters. In this talk, I will highlight three clusters, one from each category, and describe the capability and limitation of the AMiBA SZE data. Finally I would share some lessons that we have learned from building and characterising the telescope.

Keywords: galaxy clusters, instrumentation, radio astronomy