AMiBA: scaling relations between the integrated Compton-y and X-ray derived temperature, mass, and luminosity

We investigate the scaling relations between the X-ray and the thermal Sunyaev-Zel'dovich Effect (SZE) properties of clusters of galaxies, using data taken during 2007 by the Y.T. Lee Array for Microwave Background Anisotropy (AMiBA) at 94 GHz for the six clusters A1689, A1995, A2142, A2163, A2261, and A2390. The scaling relations relate the integrated Compton-y parameter Y_{2500} to the X-ray derived gas temperature T_{e}, total mass M_{2500}, and bolometric luminosity L_X within r_{2500}. Our results for the power-law index and normalization are both consistent with the self-similar model and other studies in the literature except for the Y_{2500}-L_X relation, for which a physical explanation is given though further investigation may be still needed. Our results not only provide confidence for the AMiBA project but also support our understanding of galaxy clusters.Comment: Accepted by ApJ; 8 pages, 3 figures, 5 table

AMiBA Wideband Analog Correlator

A wideband analog correlator has been constructed for the Yuan-Tseh Lee Array for Microwave Background Anisotropy. Lag correlators using analog multipliers provide large bandwidth and moderate frequency resolution. Broadband IF distribution, backend signal processing and control are described. Operating conditions for optimum sensitivity and linearity are discussed. From observations, a large effective bandwidth of around 10 GHz has been shown to provide sufficient sensitivity for detecting cosmic microwave background variations.Comment: 28 pages, 23 figures, ApJ in press

AMiBA: Broadband Heterodyne CMB Interferometry

The Y. T. Lee Array for Microwave Background (AMiBA) has reported the first science results on the detection of galaxy clusters via the Sunyaev Zel'dovich effect. The science objectives required small reflectors in order to sample large scale structures (20') while interferometry provided modest resolutions (2'). With these constraints, we designed for the best sensitivity by utilizing the maximum possible continuum bandwidth matched to the atmospheric window at 86-102GHz, with dual polarizations. A novel wide-band analog correlator was designed that is easily expandable for more interferometer elements. MMIC technology was used throughout as much as possible in order to miniaturize the components and to enhance mass production. These designs will find application in other upcoming astronomy projects. AMiBA is now in operations since 2006, and we are in the process to expand the array from 7 to 13 elements.Comment: 10 pages, 6 figures, ApJ in press; a version with high resolution figures available at http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/AMiBA7/mtc_highreso.pd

Mass and Hot Baryons in Massive Galaxy Clusters from Subaru Weak Lensing and AMiBA SZE Observations

We present a multiwavelength analysis of a sample of four hot (T_X>8keV) X-ray galaxy clusters (A1689, A2261, A2142, and A2390) using joint AMiBA Sunyaev-Zel'dovich effect (SZE) and Subaru weak lensing observations, combined with published X-ray temperatures, to examine the distribution of mass and the intracluster medium (ICM) in massive cluster environments. Our observations show that A2261 is very similar to A1689 in terms of lensing properties. Many tangential arcs are visible around A2261, with an effective Einstein radius \sim 40 arcsec (at z \sim 1.5), which when combined with our weak lensing measurements implies a mass profile well fitted by an NFW model with a high concentration c_{vir} \sim 10, similar to A1689 and to other massive clusters. The cluster A2142 shows complex mass substructure, and displays a shallower profile (c_{vir} \sim 5), consistent with detailed X-ray observations which imply recent interaction. The AMiBA map of A2142 exhibits an SZE feature associated with mass substructure lying ahead of the sharp north-west edge of the X-ray core suggesting a pressure increase in the ICM. For A2390 we obtain highly elliptical mass and ICM distributions at all radii, consistent with other X-ray and strong lensing work. Our cluster gas fraction measurements, free from the hydrostatic equilibrium assumption, are overall in good agreement with published X-ray and SZE observations, with the sample-averaged gas fraction of = 0.133 \pm 0.027, for our sample = (1.2 \pm 0.1) \times 10^{15} M_{sun} h^{-1}. When compared to the cosmic baryon fraction f_b = \Omega_b/\Omega_m constrained by the WMAP 5-year data, this indicates /f_b = 0.78 \pm 0.16, i.e., (22 \pm 16)% of the baryons are missing from the hot phase of clusters.Comment: accepted for publication in ApJ; high resolution figures available at http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/AMiBA7/ms_highreso.pd

Platform Deformation Phase Correction for the AMiBA-13 Coplanar Interferometer

[[abstract]]We present a new way to solve the platform deformation problem of coplanar interferometers. The platform of a coplanar interferometer can be deformed due to driving forces and gravity. A deformed platform will induce extra components into the geometric delay of each baseline and change the phases of observed visibilities. The reconstructed images will also be diluted due to the errors of the phases. The platform deformations of The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) were modeled based on photogrammetry data with about 20 mount pointing positions. We then used the differential optical pointing error between two optical telescopes to fit the model parameters in the entire horizontal coordinate space. With the platform deformation model, we can predict the errors of the geometric phase delays due to platform deformation with a given azimuth and elevation of the targets and calibrators. After correcting the phases of the radio point sources in the AMiBA interferometric data, we recover 50%-70% flux loss due to phase errors. This allows us to restore more than 90% of a source flux. The method outlined in this work is not only applicable to the correction of deformation for other coplanar telescopes but also to single-dish telescopes with deformation problems. This work also forms the basis of the upcoming science results of AMiBA-13.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]電子版[[booktype]]紙本[[countrycodes]]US

The Yuan-Tseh Lee Array for Microwave Background Anisotropy

The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is the first interferometer dedicated to studying the cosmic microwave background (CMB) radiation at 3mm wavelength. The choice of 3mm was made to minimize the contributions from foreground synchrotron radiation and Galactic dust emission. The initial configuration of seven 0.6m telescopes mounted on a 6-m hexapod platform was dedicated in October 2006 on Mauna Loa, Hawaii. Scientific operations began with the detection of a number of clusters of galaxies via the thermal Sunyaev-Zel'dovich effect. We compare our data with Subaru weak lensing data in order to study the structure of dark matter. We also compare our data with X-ray data in order to derive the Hubble constant.Comment: accepted for publication in ApJ (13 pages, 7 figures); a version with high resolution figures available at http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/AMiBA7/pho_highreso.pd

AMiBA: Sunyaev-Zel'Dovich Effect-derived Properties and Scaling Relations of Massive Galaxy Clusters

99學年度劉國欽研究獎助論文 100學年度劉國欽升等參考著作[[abstract]]The Sunyaev-Zel'dovich Effect (SZE) has been observed toward six massive galaxy clusters, at redshifts 0.091 ≤ z ≤ 0.322 in the 86-102 GHz band with the Y. T. Lee Array for Microwave Background Anisotropy (AMiBA). We modify an iterative method, based on the isothermal β models, to derive the electron temperature T e, total mass M t, gas mass M g, and integrated Compton Y within r 2500, from the AMiBA SZE data. Non-isothermal universal temperature profile (UTP) β models are also considered in this paper. These results are in good agreement with those deduced from other observations. We also investigate the embedded scaling relations, due to the assumptions that have been made in the method we adopted, between these purely SZE-deduced T e, M t, M g, and Y. Our results suggest that cluster properties may be measurable with SZE observations alone. However, the assumptions built into the pure-SZE method bias the results of scaling relation estimations and need further study.[[journaltype]]國外[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子版[[countrycodes]]US