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AMiBA

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For the non-profit organization also known as AMIBA, see American Independent Business Alliance.
Array for Microwave Background Anisotropy (AMiBA)
AMiBA 1.jpg
AMiBA during construction in 2006
Location(s) Mauna Loa, Hawaii
Coordinates 19°32′10″N 155°34′31″W / 19.536194°N 155.575278°W / 19.536194; -155.575278Coordinates: 19°32′10″N 155°34′31″W / 19.536194°N 155.575278°W / 19.536194; -155.575278
Altitude 3,396 m
Wavelength 3 mm (86–102 GHz)
Built 2000–2006
First light September 2006
Telescope style Interferometer
Diameter 0.576 m
Angular resolution 6 arcminutes (AMiBA7);
2 arcminutes (AMiBA13)
Mounting Hexapod platform
Dome Retractable shelter
Website amiba.asiaa.sinica.edu.tw
Commons page Related media on Wikimedia Commons

The Yuan-Tseh Lee Array for Microwave Background Anisotropy, also known as the Array for Microwave Background Anisotropy (AMiBA), is a radio telescope designed to observe the cosmic microwave background and the Sunyaev-Zel'dovich effect in clusters of galaxies. It is located on Mauna Loa in Hawaii, at 3,396 metres (11,142 ft) above sea level.

AMiBA was originally configured as a 7-element interferometer atop a hexapod mount. Observations at a wavelength of 3 mm (86–102 GHz) started in October 2006, and the detections of six clusters by the Sunyaev-Zel'dovich effect were announced in 2008. In 2009 the telescope was upgraded to 13 elements, and it is capable of further expansion to 19 elements. AMiBA is the result of a collaboration between the Academia Sinica Institute of Astronomy and Astrophysics, the National Taiwan University and the Australia Telescope National Facility, and also involves researchers from other universities.

Design[edit]

The rear of the hexapod mount

AMiBA was initially configured as a 7-element interferometer, using 0.576 m Cassegrain dishes mounted on a 6 m carbon fibre hexapod mount. It is located on Mauna Loa, Hawaii, and observes at 3 mm (86–102 GHz) to minimize foreground emission from other, non-thermal sources. The telescope has a retractable shelter, made from seven steel trusses and PVC fabric.[1]

The receivers are based on Monolithic Microwave Integrated Circuit (MMIC) technology, with low noise amplifiers cooled to 15 K, which have 20 GHz bandwidths[1] and provide 46 dB of amplification.[2] The signals are mixed with a local oscillator to reduce their frequency, prior to correlation with an analog correlator. The system temperatures are between 55 and 75 K.[1]

AMiBA started in 2000, with funding for 4 years from the Cosmology and Particle Astrophysics Project of the Taiwan Ministry of Education.[3] A 2-element prototype was set up on Mauna Loa in 2002.[2] Further funding for a second 4 years was provided by the National Science Council.[3] The mount arrived on site in 2004, and the platform was installed in 2005. The first 7 elements were then installed ("AMiBA7"), and the telescope's first light was in September 2006, observing Jupiter. The telescope was dedicated in October 2006 to Yuan-Tseh Lee. The array was upgraded to have thirteen 1.2 m dishes in 2009 ("AMiBA13").[1] After extensive testing and calibration, scientific observations resumed in 2011. It is further expandable up to 19 elements.[2]

Observations[edit]

The primary goal of AMiBA is to observe both the temperature and polarization anisotropies in the Cosmic Microwave Background at multipoles between 800 and 8,000 (corresponding to between 2 and 20 arcminutes on the sky), as well as observing the thermal Sunyaev-Zel'dovich effect in clusters of galaxies,[1] which has a maximum decrement around 100 GHz.[2] In its initial configuration, it measures up to multipoles of 3,000[1] with a resolution of around 6 arcminutes.[4] The telescope only observes at night during good weather, using planets for calibration.[2]

Six clusters were imaged in 2007: the Abell clusters 1689, 1995, 2142, 2163, 2261 and 2390,[1] which have redshifts between 0.091 and 0.322.[2] For the largest and brightest four of these—Abell 1689, 2261, 2142 and 2390—comparisons were made with X-ray and Subaru weak lensing data to study the cluster layout and radial properties, specifically of the mass profiles and baryon content.[4] It is predicted that AMiBA with either 13 or 19 elements will be able to detect around 80 clusters per year via the SZ effect.[3]

Collaboration[edit]

AMiBA is the result of a collaboration between the Academia Sinica Institute of Astronomy and Astrophysics, the National Taiwan University and the Australia Telescope National Facility. It also involves researchers from the Harvard-Smithsonian Center for Astrophysics, the National Radio Astronomy Observatory, the University of Hawaii, the University of Bristol, Nottingham Trent University, the Canadian Institute for Theoretical Astrophysics and the Carnegie-Mellon University.[1]

References[edit]

  1. ^ a b c d e f g h Ho, Paul et al. (2008). "The Yuan-Tseh Lee Array for Microwave Background Anisotropy". arXiv:0810.1871. Bibcode:2009ApJ...694.1610H. doi:10.1088/0004-637X/694/2/1610. 
  2. ^ a b c d e f Wu, Jiun-Huei Proty et al. (2008). "AMiBA Observations, Data Analysis and Results for Sunyaev-Zel'dovich Effects". arXiv:0810.1015. 
  3. ^ a b c Ho, Paul T.P. et al. (28 June 2008b). "The Yuan Tseh Lee AMiBA Project". Modern Physics Letters A (MPLA) 23 (17/20): 1243–1251. Bibcode:2008MPLA...23.1243H. doi:10.1142/S021773230802762X. 
  4. ^ a b Umetsu, Keiichi et al. (2008). "Mass and Hot Baryons in Massive Galaxy Clusters from Subaru Weak Lensing and AMiBA SZE Observations". arXiv:0810.0969. Bibcode:2009ApJ...694.1643U. doi:10.1088/0004-637X/694/2/1643.