The Arcminute Microkelvin Imager (AMI) consists of a pair of

interferometric Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber op ...

radio telescope A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency ...

s - the Small and Large Arrays - located at the Mullard Radio Astronomy Observatory near Cambridge. AMI was designed, built and is operated by the Cavendish Astrophysics Group. AMI was designed, primarily, for the study of

galaxy clusters A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-la ...

by observing secondary

anisotropies Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...

in the cosmic microwave background (CMB) arising from the Sunyaev–Zel'dovich (SZ) effect. Both arrays are used to observe

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

with

frequencies Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

between 12 and 18 GHz, and have very similar system designs. The telescopes are used to observe both previously known galaxy clusters, in an attempt to determine, for example, their masses and temperatures, and to carry out surveys, in order to locate previously undiscovered clusters.

AMI Large Array

The AMI Large Array (AMI LA) is composed of eight 12.8-metre-diameter, equatorially mounted

parabolic antenna A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or pa ...

s, which were previously part of the Ryle Telescope. The antennas are separated by distances ranging between 18 and 110 m. The telescope has an

angular resolution Angular resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution. ...

of approximately 30 arcseconds. The LA is used to image the

radio sources An astronomical radio source is an object in outer space that emits strong radio waves. Radio emission comes from a wide variety of sources. Such objects are among the most extreme and energetic physical processes in the universe. History In 193 ...

(mainly radio galaxies) that contaminate the Small Array observations of the CMB. The LA is being used to carry out the Tenth Cambridge Survey of radio sources. The first results from the survey were used to extend the measured 15-GHz source counts to sub- millijansky levels; this is an order of magnitude deeper than achieved by the Ninth Cambridge Survey, which was the first survey of significant sky coverage at a comparable radio frequency.

AMI Small Array

Arcminute microkelvin imager small array

The AMI Small Array (AMI SA) consists of 10 3.7-m-diameter antennas, similar in design to those of the LA. They are arranged at intervals of between 5 and 20 m. The SA has an angular resolution of approximately 3 arcminutes and is used to image, at high resolution, the galaxy clusters of interest. The SA is being used to search for previously unknown galaxy clusters; results from the first such cluster, detected using AMI, were released in December 2010. In addition to observations of galaxy clusters, the SA has been used to carry out observations, amongst other things, towards supernova remnants and anomalous microwave emission.

References

* * * * * * * {{Authority control Cosmic microwave background experiments Cavendish Laboratory Interferometric telescopes Radio telescopes

AMI Large Array

AMI Small Array

See also

References