The cosmic microwave background is microwave radiation that fills all space in the observable universe. It is a remnant that provides an important source of data on the primordial universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive radio telescope detects a faint background glow that is almost uniform and is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1965 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s.
The Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe, was a NASA spacecraft operating from 2001 to 2010 which measured temperature differences across the sky in the cosmic microwave background (CMB) – the radiant heat remaining from the Big Bang. Headed by Professor Charles L. Bennett of Johns Hopkins University, the mission was developed in a joint partnership between the NASA Goddard Space Flight Center and Princeton University. The WMAP spacecraft was launched on 30 June 2001 from Florida. The WMAP mission succeeded the COBE space mission and was the second medium-class (MIDEX) spacecraft in the NASA Explorer program. In 2003, MAP was renamed WMAP in honor of cosmologist David Todd Wilkinson (1935–2002), who had been a member of the mission's science team. After nine years of operations, WMAP was switched off in 2010, following the launch of the more advanced Planck spacecraft by European Space Agency (ESA) in 2009.
The Cosmic Background Explorer, also referred to as Explorer 66, was a NASA satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation of the universe and provide measurements that would help shape our understanding of the cosmos.
The Sunyaev–Zeldovich effect is the spectral distortion of the cosmic microwave background (CMB) through inverse Compton scattering by high-energy electrons in galaxy clusters, in which the low-energy CMB photons receive an average energy boost during collision with the high-energy cluster electrons. Observed distortions of the cosmic microwave background spectrum are used to detect the disturbance of density in the universe. Using the Sunyaev–Zeldovich effect, dense clusters of galaxies have been observed.
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors.
BOOMERanG experiment was an experiment that flew a telescope on a (high-altitude) balloon and measured the cosmic microwave background radiation of a part of the sky during three sub-orbital flights. It was the first experiment to make large, high-fidelity images of the CMB temperature anisotropies, and is best known for the discovery in 2000 that the geometry of the universe is close to flat, with similar results from the competing MAXIMA experiment.
The South Pole Telescope (SPT) is a 10-metre (390 in) diameter telescope located at the Amundsen–Scott South Pole Station, Antarctica. The telescope is designed for observations in the microwave, millimeter-wave, and submillimeter-wave regions of the electromagnetic spectrum, with the particular design goal of measuring the faint, diffuse emission from the cosmic microwave background (CMB). The first major survey with the SPT—designed to find distant, massive, clusters of galaxies through their interaction with the CMB, with the goal of constraining the dark energy equation of state—was completed in October 2011. In early 2012, a new camera (SPTpol) was installed on the SPT with even greater sensitivity and the capability to measure the polarization of incoming light. This camera operated from 2012–2016 and was used to make unprecedentedly deep high-resolution maps of hundreds of square degrees of the Southern sky. In 2017, the third-generation camera SPT-3G was installed on the telescope, providing nearly an order-of-magnitude increase in mapping speed over SPTpol.
Charles L. Bennett is an American observational astrophysicist. He is a Bloomberg Distinguished Professor, the Alumni Centennial Professor of Physics and Astronomy and a Gilman Scholar at Johns Hopkins University. He is the Principal Investigator of NASA's highly successful Wilkinson Microwave Anisotropy Probe (WMAP).
The Degree Angular Scale Interferometer (DASI) was a telescope installed at the U.S. National Science Foundation's Amundsen–Scott South Pole Station in Antarctica. It was a 13-element interferometer operating between 26 and 36 GHz in ten bands. The instrument is similar in design to the Cosmic Background Imager (CBI) and the Very Small Array (VSA). In 2001 The DASI team announced the most detailed measurements of the temperature, or power spectrum of the cosmic microwave background (CMB). These results contained the first detection of the 2nd and 3rd acoustic peaks in the CMB, which were important evidence for inflation theory. This announcement was done in conjunction with the BOOMERanG and MAXIMA experiment. In 2002 the team reported the first detection of polarization anisotropies in the CMB.
ACBAR was an experiment to measure the anisotropy of the Cosmic microwave background. It was active 2000-2008.
The Mobile Anisotropy Telescope (MAT), also known as the Mobile Anisotropy Telescope on Cerro Toco was a ground-based radio telescope experiment to measure the anisotropy of the cosmic microwave background (CMB). The experiment was conducted at an observation site on the southern slopes of Cerro Toco in the Atacama Desert of northern Chile. It was a collaboration between the physics departments at Princeton University and the University of Pennsylvania.
QMAP was a balloon experiment to measure the anisotropy of the cosmic microwave background (CMB). It flew twice in 1996, and was used with an interlocking scan of the skies to produce CMB maps at angular scales between 0.7° and 9°.
The CMB Cold Spot or WMAP Cold Spot is a region of the sky seen in microwaves that has been found to be unusually large and cold relative to the expected properties of the cosmic microwave background radiation (CMBR). The "Cold Spot" is approximately 70 μK (0.00007 K) colder than the average CMB temperature, whereas the root mean square of typical temperature variations is only 18 μK. At some points, the "cold spot" is 140 μK colder than the average CMB temperature.
In cosmology, the steady-state model or steady state theory is an alternative to the Big Bang theory. In the steady-state model, the density of matter in the expanding universe remains unchanged due to a continuous creation of matter, thus adhering to the perfect cosmological principle, a principle that says that the observable universe is always the same at any time and any place.
Cold Big Bang is a designation used in cosmology to denote an absolute zero temperature at the beginning of the Universe, instead of a (hot) Big Bang.
Calvin Barth Netterfield, known as Barth Netterfield, is a Canadian astrophysicist, and a Professor in the Department of Astronomy and the Department of Physics at the University of Toronto. He is a leading expert in the development of balloon-borne telescopes. These are astrophysical experiments that are lifted into the stratosphere by high-altitude balloons where they conduct observations that would be hindered by atmospheric interference if done on the ground. Netterfield is primarily known for his work in observational cosmology, specifically in developing instrumentation to observe the cosmic microwave background (CMB) radiation. Most notably, he was a key member of the instrument team for BOOMERANG, the experiment that made one of the first accurate determinations of the age, geometry, and mass-energy content of the universe. More recently, he has delved into the field of submillimetre astronomy and the physics of star formation, through his involvement with the BLAST telescope. Netterfield was featured prominently in BLAST!, a documentary film about the 2005 and 2006 flights of BLAST from Sweden and Antarctica.
The Cosmology Large Angular Scale Surveyor (CLASS) is an array of microwave telescopes at a high-altitude site in the Atacama Desert of Chile as part of the Parque Astronómico de Atacama. The CLASS experiment aims to improve our understanding of cosmic dawn when the first stars turned on, test the theory of cosmic inflation, and distinguish between inflationary models of the very early universe by making precise measurements of the polarization of the Cosmic Microwave Background (CMB) over 65% of the sky at multiple frequencies in the microwave region of the electromagnetic spectrum.
The "axis of evil" is a name given to the apparent correlation between the plane of the Solar System and aspects of the cosmic microwave background (CMB). It gives the plane of the Solar System and hence the location of Earth a greater significance than might be expected by chance – a result which has been claimed to be evidence of a departure from the Copernican principle as assumed in the concordance model.
In cosmological inflation, within the slow-roll paradigm, the Lyth argument places a theoretical upper bound on the amount of gravitational waves produced during inflation, given the amount of departure from the homogeneity of the cosmic microwave background (CMB).
