Atacama Cosmology Telescope

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Atacama Cosmology Telescope
Atacama cosmology telescope toco.jpg
The Atacama Cosmology Telescope, with Cerro Toco in the background
Alternative namesACTpol OOjs UI icon edit-ltr-progressive.svg
Part of Llano de Chajnantor Observatory   OOjs UI icon edit-ltr-progressive.svg
Location(s)Atacama Desert
Coordinates 22°57′31″S67°47′15″W / 22.9586°S 67.7875°W / -22.9586; -67.7875 OOjs UI icon edit-ltr-progressive.svg
Wavelength 28, 41, 90, 150, 220 GHz (1.07, 0.73, 0.33, 0.20, 0.14 cm)
First light 22 October 2007  OOjs UI icon edit-ltr-progressive.svg
Telescope style cosmic microwave background experiment
radio telescope   OOjs UI icon edit-ltr-progressive.svg
Diameter6 meter
Website act.princeton.edu OOjs UI icon edit-ltr-progressive.svg
Relief Map of Chile.jpg
Red pog.svg
Location of Atacama Cosmology Telescope
  Commons-logo.svg Related media on Commons
[ edit on Wikidata]

The Atacama Cosmology Telescope (ACT) was a cosmological millimeter-wave telescope located on Cerro Toco in the Atacama Desert in the north of Chile. [1] ACT made high-sensitivity, arcminute resolution, microwave-wavelength surveys of the sky in order to study the cosmic microwave background radiation (CMB), the relic radiation left by the Big Bang process. Located 40 km from San Pedro de Atacama, at an altitude of 5,190 metres (17,030 ft), it was one of the highest ground-based telescopes in the world. [lower-alpha 1]

Contents

Cosmic microwave background experiments like ACT, the South Pole Telescope, the WMAP satellite, and the Planck satellite have provided foundational evidence for the standard Lambda-CDM model of cosmology. ACT first detected seven acoustic peaks in the power spectrum of the CMB, discovered the most extreme galaxy cluster and made the first statistical detection of the motions of clusters of galaxies via the pairwise kinematic Sunyaev-Zeldovich Effect. [3]

ACT was built in 2007 and saw first light in October 2007 with its first receiver, the Millimeter Bolometer Array Camera (MBAC). ACT had two major receiver upgrades which enabled polarization sensitive observations: ACTPol [4] (2013–2016) and Advanced ACT [5] (2017–2022). ACT observations ended in mid-2022. ACT is funded by the US National Science Foundation.

Science goals

Measurements of cosmic microwave background radiation (CMB) by experiments such as COBE, BOOMERanG, WMAP, CBI, the South Pole Telescope and many others, have greatly advanced our knowledge of cosmology, particularly the early evolution of the universe. At the arcminute resolutions probed by ACT, the Sunyaev-Zeldovich effect, by which galaxy clusters leave an imprint on the CMB, is prominent. This method of detection provides a redshift-independent measurement of the mass of the clusters, meaning that very distant, ancient clusters are as easy to detect as nearby clusters.

Atacama Cosmology Telescope observing patches and depth map Atacama Cosmology Telescope Patches.png
Atacama Cosmology Telescope observing patches and depth map

Detection of galaxy clusters and follow-up measurements in visible and X-ray light, provide a picture of the evolution of structure in the universe since the Big Bang. This is used to improve our understanding of the nature of the mysterious dark energy which seems to be a dominant component of the universe.

High sensitivity observations of the cosmic microwave background radiation allow precision measurements of cosmological parameters, detection of galaxy clusters among other scientific goals, probing the early and late stages in the history of the evolution of the universe.

Scientific highlights

Throughout its operation, ACT contributed the scientific community with:

Location

Aerial view of the Andes as seen from the vicinity of Calama, Chile. ACT is located on Cerro Toco, near Cerro Chajnantor and the Licancabur volcano. Aerial view of the Andes seen from the vicinity of Calama, Chile.png
Aerial view of the Andes as seen from the vicinity of Calama, Chile. ACT is located on Cerro Toco, near Cerro Chajnantor and the Licancabur volcano.

Water vapor in the atmosphere emits microwave radiation which contaminates measurements of the CMB, for this reason CMB telescopes benefit from arid, high-altitude locations. ACT is located in the dry and high (yet easily accessible) Chajnantor plateau in the Andean mountains in the Atacama Desert in northern Chile. Due to the exceptional observing conditions of the Atacama Desert and its accessibility by road and nearby ports, several other observatories are located in the region, including CBI, ASTE, Nanten, APEX and ALMA. These astronomical observatories and telescopes form the Llano de Chajnantor Observatory, a cluster of astronomical telescopes primarily in millimeter and sub-millimeter wavelengths.

Design

The Atacama Cosmology Telescope viewed from the top of the outer ground screen. The top half of the segmented, primary mirror can be seen above the inner ground screen that moves with the telescope. Atacama cosmology telescope top down.jpg
The Atacama Cosmology Telescope viewed from the top of the outer ground screen. The top half of the segmented, primary mirror can be seen above the inner ground screen that moves with the telescope.
The Atacama Cosmology Telescope. In this picture, the ground screen had not yet been completed, allowing the telescope to be seen. Atacama cosmology telescope night.jpg
The Atacama Cosmology Telescope. In this picture, the ground screen had not yet been completed, allowing the telescope to be seen.

Telescope

The ACT is an off-axis Gregorian telescope. This off-axis configuration is beneficial to minimize artifacts in the point spread function. The telescope reflectors consist of a six-metre (236 in) primary mirror and a two-metre (79 in) secondary mirror. Both mirrors are composed of segments, consisting of 71 (primary) and 11 (secondary) aluminum panels. These panels follow the shape of an ellipsoid of revolution and are carefully aligned to form a joint surface. Unlike most telescopes which track the rotating sky during observation, the ACT observes the sky by keeping the telescope oriented at a constant elevation and by scanning back and forth in azimuth at the relatively rapid rate of two degrees per second. The rotating portion of the telescope weighs approximately 32 tonnes (35 short tons), creating a substantial engineering challenge. A ground screen surrounding the telescope blocks contamination from microwave radiation emitted by the ground. The design, manufacture and construction of the telescope were done by Dynamic Structures in Vancouver, British Columbia.

Instrument

ACT can accommodate three instrument cameras simultaneously. Over time these cameras were upgraded from the original MBAC design to the Advanced ACT instrument progressively adding more features like polarization sensitivity and the ability to sense multiple frequencies in one instrument module. Each camera in ACT consists of a three lens system, the Gregorian focus is reimaged into a detector focal plane, a Lyot stop reimages the primary mirror allowing stray light mitigation.

The three lenses in ACT are made of cryogenically cooled anti-reflection coated silicon, a desirable material for instruments in the millimeter due to its high index of refraction (n=3). Anti-reflection coatings in ACTPol and AdvACT are made of sub-wavelength structured metamaterial silicon, an innovation in ground based CMB telescopes at the time. The optical components and the detector module are kept at a vacuum with a plastic window. A stack of filters reject infra-red radiation which is detrimental for mm-wavelength observations.

Radiation is thermally coupled to transition-edge sensor bolometers, which are read out using an array of SQUIDs.

Observations

Observations are made at resolutions of about an arcminute (1/60th of a degree) in three frequencies: 145 GHz, 215 GHz and 280 GHz. Each frequency is measured by a 3 cm × 3 cm (1.2 in × 1.2 in), 1024 element array, for a total of 3072 detectors. The detectors are superconducting transition-edge sensors, a technology whose high sensitivity allows measurements of the temperature of the CMB to within a few millionths of a degree. [16] A system of cryogenic helium refrigerators keep the detectors a third of a degree above absolute zero.

Detectors

ACT has had three generations of cameras. Each camera is the result of the development of specialized detector technology which has been optimized through the years. These cameras take advantage of superconducting transition edge sensor arrays to achieve high sensitivity.

The first array of cameras to populate the ACT focal plane (MBAC) consisted of three cameras where each one was sensitive to its own band and had no polarization sensitivity. The second generation of cameras (ACTPol) added polarization sensitivity and the first camera to be sensitive to two bands (dichroic). The third generation of cameras (AdvACT) incorporated the advances achieved in ACTPol, which allowed all cameras to be sensitive to two bands.

PhaseArraysFreq. (GHz)Sens. (μK√s)Pol.YearsPatches
MBACar114830No2008–2010Equ South
ar2217 ?No2008–2010
ar3277 ?No2010
ACTPolpa115017–29Yes2013–2015D2 D5 D6 D56 D8 BN
pa215013–18Yes2014–2016
pa39016Yes2015–2016
15021–22
AdvACTpa415018.2Yes2017–2021AA Day‑N Day‑S
22034.1
pa59812.5Yes2017–2021
15013.9
pa69811.3Yes2017–2019
15012.6
pa727 ?Yes2020–2021
39 ?

Institutions

ACT has collaborators at Princeton University, Cornell University, the University of Pennsylvania, NASA/GSFC, the Johns Hopkins University, the University of British Columbia, NIST, the Pontificia Universidad Católica de Chile, the University of KwaZulu-Natal, Perimeter Institute for Theoretical Physics, the Canadian Institute for Theoretical Astrophysics, Stanford University, Stony Brook University, Cardiff University, Argonne National Laboratory, Haverford College, Rutgers University, the University of Pittsburgh, UC Berkeley, University of Southern California, the University of Oxford, the University of Paris-Saclay, University of Illinois at Urbana-Champaign, SLAC National Accelerator Laboratory, Caltech, McGill University, the Center for Computational Astrophysics, Arizona State University, Columbia University, Carnegie Mellon University, the University of Chicago, Haverford College, Florida State University, West Chester University, Yale University, and the University of Toronto. [17]

See also

Notes

  1. ↑ The Receiver Lab Telescope (RLT), an 80 cm (31 in) instrument, is higher at 5,525 m (18,125 ft), but is not permanent as it is fixed to the roof of a movable shipping container. [2] The 2009 University of Tokyo Atacama Observatory is significantly higher than both.

Related Research Articles

<span class="mw-page-title-main">Cosmic microwave background</span> Trace radiation from the early universe

The cosmic microwave background, or relic radiation, is microwave radiation that fills all space in the observable 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.

<span class="mw-page-title-main">Cosmological principle</span> Theory that the universe is the same in all directions

In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course of evolution of the matter field that was initially laid down by the Big Bang.

<span class="mw-page-title-main">Sunyaev–Zeldovich effect</span> Spectral distortion of cosmic microwave background in galaxy clusters

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.

<span class="mw-page-title-main">Arcminute Microkelvin Imager</span>

The Arcminute Microkelvin Imager (AMI) consists of a pair of interferometric radio telescopes - 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 by observing secondary anisotropies in the cosmic microwave background (CMB) arising from the Sunyaev–Zel'dovich (SZ) effect. Both arrays are used to observe radiation with frequencies 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.

<span class="mw-page-title-main">Very Small Array</span> Radio telescope in the Canary Islands

The Very Small Array (VSA) was a 14-element interferometric radio telescope operating between 26 and 36 GHz that is used to study the cosmic microwave background radiation. It was a collaboration between the University of Cambridge, University of Manchester and the Instituto de Astrofisica de Canarias (Tenerife), and was located at the Observatorio del Teide on Tenerife. The array was built at the Mullard Radio Astronomy Observatory by the Cavendish Astrophysics Group and Jodrell Bank Observatory, and was funded by PPARC. The design was strongly based on the Cosmic Anisotropy Telescope.

The Combined Array for Research in Millimeter-wave Astronomy (CARMA) was an astronomical instrument comprising 23 radio telescopes, dedicated in 2006. These telescopes formed an astronomical interferometer where all the signals are combined in a purpose-built computer to produce high-resolution astronomical images. The telescopes ceased operation in April 2015 and were relocated to the Owens Valley Radio Observatory for storage.

<span class="mw-page-title-main">South Pole Telescope</span> Telescope at the South Pole

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). Key results include a wide and deep survey of discovering hundreds of clusters of galaxies using the Sunyaev–Zel'dovich effect, a sensitive 5 arcminute CMB power spectrum survey, and the first detection of B-mode polarized CMB.

<span class="mw-page-title-main">Llano de Chajnantor Observatory</span> Observatory

Llano de Chajnantor Observatory is the name for a group of astronomical observatories located at an altitude of over 4,800 m (15,700 ft) in the Atacama Desert of northern Chile. The site is in the Antofagasta Region approximately 50 kilometres (31 mi) east of the town of San Pedro de Atacama. The exceptionally arid climate of the area is inhospitable to humans, but creates an excellent location for millimeter, submillimeter, and mid-infrared astronomy. This is because water vapour absorbs and attenuates submillimetre radiation. Llano de Chajnantor is home to the largest and most expensive astronomical telescope project in the world, the Atacama Large Millimeter Array (ALMA). Llano de Chajnantor and the surrounding area has been designated as the Chajnantor Science Reserve by the government of Chile.

<span class="mw-page-title-main">Spider (polarimeter)</span> Balloon-borne astronomical experiment

Spider is a balloon-borne experiment designed to search for primordial gravitational waves imprinted on the cosmic microwave background (CMB). Measuring the strength of this signal puts limits on inflationary theory.

<span class="mw-page-title-main">Millimeter Anisotropy eXperiment IMaging Array</span> Balloon package that measured the Universes geometry

The Millimeter Anisotropy eXperiment IMaging Array (MAXIMA) experiment was a balloon-borne experiment funded by the United States NSF, NASA, and Department of Energy, and operated by an international collaboration headed by the University of California, to measure the fluctuations of the cosmic microwave background. It consisted of two flights, one in August 1998 and one in June 1999. For each flight the balloon was started at the Columbia Scientific Balloon Facility in Palestine, Texas and flew to an altitude of 40,000 metres for over 8 hours. For the first flight it took data from about 0.3 percent of the sky of the northern region near the Draco constellation. For the second flight, known as MAXIMA-II, twice the area was observed, this time in the direction of Ursa Major.

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.

<span class="mw-page-title-main">QUIET</span> Astronomical observatory for studying the cosmic microwave background

QUIET was an astronomy experiment to study the polarization of the cosmic microwave background radiation. QUIET stands for Q/U Imaging ExperimenT. The Q/U in the name refers to the ability of the telescope to measure the Q and U Stokes parameters simultaneously. QUIET was located at an elevation of 5,080 metres at Llano de Chajnantor Observatory in the Chilean Andes. It began observing in late 2008 and finished observing in December 2010.

<span class="mw-page-title-main">AMiBA</span> Radio telescope on Mauna Loa, Hawaii

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.

<span class="mw-page-title-main">BICEP and Keck Array</span> Series of cosmic microwave background experiments at the South Pole

BICEP and the Keck Array are a series of cosmic microwave background (CMB) experiments. They aim to measure the polarization of the CMB; in particular, measuring the B-mode of the CMB. The experiments have had five generations of instrumentation, consisting of BICEP1, BICEP2, the Keck Array, BICEP3, and the BICEP Array. The Keck Array started observations in 2012 and BICEP3 has been fully operational since May 2016, with the BICEP Array beginning installation in 2017/18.

<span class="mw-page-title-main">POLARBEAR</span>

POLARBEAR is a cosmic microwave background polarization experiment located in the Atacama Desert of northern Chile in the Antofagasta Region. The POLARBEAR experiment is mounted on the Huan Tran Telescope (HTT) at the James Ax Observatory in the Chajnantor Science Reserve. The HTT is located near the Atacama Cosmology Telescope on the slopes of Cerro Toco at an altitude of nearly 5,200 m (17,100 ft).

<span class="mw-page-title-main">Cosmology Large Angular Scale Surveyor</span> Microwave telescope array in Chile

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.

<span class="mw-page-title-main">9io9</span> Galaxy in the constellation Cetus

ASW0009io9 (9io9) is a gravitationally lensed system of two galaxies. The nearer galaxy is approximately 2 billion light-years (610 Mpc) from Earth and is designated SDSS J020941.27+001558.4, while the lensed galaxy is 10 billion light-years (3.1 Gpc) distant and is designated ASW0009io9. It was discovered in January 2014 by a group of citizen scientists, while classifying images on the website Spacewarps.org. The discovery was announced on the BBC television programme Stargazing Live.

<span class="mw-page-title-main">Atacama B-Mode Search</span>

The Atacama B-Mode Search (ABS) was an experiment to 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). ABS was located at a high-altitude site in the Atacama Desert of Chile as part of the Parque Astronómico de Atacama. ABS began observations in February 2012 and completed observations in October 2014.

<span class="mw-page-title-main">Simons Observatory</span> Observatory in Chile

The Simons Observatory is located in the high Atacama Desert in Northern Chile inside the Chajnator Science Preserve, at an altitude of 5,200 meters (17,000 ft). The Atacama Cosmology Telescope (ACT) and the Simons Array are located nearby and these experiments are currently making observations of the Cosmic Microwave Background (CMB). Their goals are to study how the universe began, what it is made of, and how it evolved to its current state. The Simons Observatory shares many of the same goals but aims to take advantage of advances in technology to make far more precise and diverse measurements. In addition, it is envisaged that many aspects of the Simons Observatory will be pathfinders for the future CMB-S4 array.

References

  1. ↑ Fowler, J. W.; Niemack, M. D.; Dicker, S. R.; Aboobaker, A. M.; Ade, P. A. R.; Battistelli, E. S.; Devlin, M. J.; Fisher, R. P.; Halpern, M.; Hargrave, P. C.; Hincks, A. D. (10 June 2007). "Optical design of the Atacama Cosmology Telescope and the Millimeter Bolometric Array Camera". Applied Optics. 46 (17): 3444–3454. arXiv: astro-ph/0701020 . Bibcode:2007ApOpt..46.3444F. doi:10.1364/AO.46.003444. ISSN   0003-6935. PMID   17514303. S2CID   10833374.
  2. ↑ Marrone; et al. (2005). "Observations in the 1.3 and 1.5 THz Atmospheric Windows with the Receiver Lab Telescope". Sixteenth International Symposium on Space Terahertz Technology: 64. arXiv: astro-ph/0505273 . Bibcode:2005stt..conf...64M.
  3. ↑ Hand, Nick; Addison, Graeme E.; Aubourg, Eric; Battaglia, Nick; Battistelli, Elia S.; Bizyaev, Dmitry; Bond, J. Richard; Brewington, Howard; Brinkmann, Jon; Brown, Benjamin R.; Das, Sudeep; Dawson, Kyle S.; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando (23 July 2012). "Evidence of Galaxy Cluster Motions with the Kinematic Sunyaev-Zel'dovich Effect". Physical Review Letters. 109 (4): 041101. arXiv: 1203.4219 . doi: 10.1103/PhysRevLett.109.041101 . ISSN   0031-9007. PMID   23006072.
  4. ↑ Niemack, M. D.; Ade, P. A. R.; Aguirre, J.; Barrientos, F.; Beall, J. A.; Bond, J. R.; Britton, J.; Cho, H. M.; Das, S.; Devlin, M. J.; Dicker, S. (16 July 2010). "ACTPol: a polarization-sensitive receiver for the Atacama Cosmology Telescope". In Holland, Wayne S.; Zmuidzinas, Jonas (eds.). Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V. Vol. 7741. San Diego, California, USA. pp. 537–557. arXiv: 1006.5049 . doi:10.1117/12.857464. S2CID   27705474.{{cite book}}: CS1 maint: location missing publisher (link)
  5. ↑ Henderson, S. W.; Allison, R.; Austermann, J.; Baildon, T.; Battaglia, N.; Beall, J. A.; Becker, D.; De Bernardis, F.; Bond, J. R.; Calabrese, E.; Choi, S. K. (1 August 2016). "Advanced ACTPol Cryogenic Detector Arrays and Readout". Journal of Low Temperature Physics. 184 (3): 772–779. arXiv: 1510.02809 . Bibcode:2016JLTP..184..772H. doi:10.1007/s10909-016-1575-z. ISSN   1573-7357. S2CID   53411729.
  6. ↑ Dunkley, J.; Hlozek, R.; Sievers, J.; Acquaviva, V.; Ade, P. A. R.; Aguirre, P.; Amiri, M.; Appel, J. W.; Barrientos, L. F.; Battistelli, E. S.; Bond, J. R.; Brown, B.; Burger, B.; Chervenak, J.; Das, S. (20 September 2011). "The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power Spectrum". The Astrophysical Journal. 739 (1): 52. arXiv: 1009.0866 . doi:10.1088/0004-637X/739/1/52. ISSN   0004-637X. S2CID   31436593.
  7. ↑ Das, Sudeep; Sherwin, Blake D.; Aguirre, Paula; Appel, John W.; Bond, J. Richard; Carvalho, C. Sofia; Devlin, Mark J.; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W.; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D. (5 July 2011). "Detection of the Power Spectrum of Cosmic Microwave Background Lensing by the Atacama Cosmology Telescope". Physical Review Letters. 107 (2): 021301. arXiv: 1103.2124 . doi: 10.1103/PhysRevLett.107.021301 . PMID   21797590.
  8. ↑ Menanteau, Felipe; Hughes, John P.; Sifón, Cristóbal; Hilton, Matt; González, Jorge; Infante, Leopoldo; Felipe Barrientos, L.; Baker, Andrew J.; Bond, John R.; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Hajian, Amir; Hincks, Adam D.; Kosowsky, Arthur (20 March 2012). "THE ATACAMA COSMOLOGY TELESCOPE: ACT-CL J0102–4915 "EL GORDO," A MASSIVE MERGING CLUSTER AT REDSHIFT 0.87". The Astrophysical Journal. 748 (1): 7. arXiv: 1109.0953 . doi:10.1088/0004-637X/748/1/7. ISSN   0004-637X. S2CID   204931508.
  9. ↑ Ferreira, P. G.; Juszkiewicz, R.; Feldman, H. A.; Davis, M.; Jaffe, A. H. (10 April 1999). "Streaming Velocities as a Dynamical Estimator of Ω". The Astrophysical Journal. 515 (1): L1–L4. doi: 10.1086/311959 . ISSN   0004-637X.
  10. ↑ Hand, Nick; Addison, Graeme E.; Aubourg, Eric; Battaglia, Nick; Battistelli, Elia S.; Bizyaev, Dmitry; Bond, J. Richard; Brewington, Howard; Brinkmann, Jon; Brown, Benjamin R.; Das, Sudeep; Dawson, Kyle S.; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando (23 July 2012). "Evidence of Galaxy Cluster Motions with the Kinematic Sunyaev-Zel'dovich Effect". Physical Review Letters. 109 (4): 041101. arXiv: 1203.4219 . doi: 10.1103/PhysRevLett.109.041101 . ISSN   0031-9007. PMID   23006072.
  11. ↑ Choi, Steve K.; Hasselfield, Matthew; Ho, Shuay-Pwu Patty; Koopman, Brian; Lungu, Marius; Abitbol, Maximilian H.; Addison, Graeme E.; Ade, Peter A. R.; Aiola, Simone; Alonso, David; Amiri, Mandana; Amodeo, Stefania; Angile, Elio; Austermann, Jason E.; Baildon, Taylor (30 December 2020). "The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz". Journal of Cosmology and Astroparticle Physics. 2020 (12): 045. arXiv: 2007.07289 . doi:10.1088/1475-7516/2020/12/045. ISSN   1475-7516. S2CID   220525420.
  12. ↑ Madhavacheril, Mathew; Sehgal, Neelima; Allison, Rupert; Battaglia, Nick; Bond, J. Richard; Calabrese, Erminia; Caligiuri, Jerod; Coughlin, Kevin; Crichton, Devin; Datta, Rahul; Devlin, Mark J.; Dunkley, Joanna; Dünner, Rolando; Fogarty, Kevin; Grace, Emily; Hajian, Amir; Hasselfield, Matthew; Hill, J. Colin; Hilton, Matt; Hincks, Adam D.; Hlozek, Renée; Hughes, John P.; Kosowsky, Arthur; Louis, Thibaut; Lungu, Marius; McMahon, Jeff; Moodley, Kavilan; Munson, Charles; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Niemack, Michael D.; Page, Lyman A.; Partridge, Bruce; Schmitt, Benjamin; Sherwin, Blake D.; Sievers, Jon; Spergel, David N.; Staggs, Suzanne T.; Thornton, Robert; Van Engelen, Alexander; Ward, Jonathan T.; Wollack, Edward J. (13 April 2015). "Evidence of Lensing of the Cosmic Microwave Background by Dark Matter Halos". Physical Review Letters. 114 (15). arXiv: 1411.7999 . doi:10.1103/PhysRevLett.114.151302.
  13. ↑ Atacama Cosmology Telescope Collaboration; Schaan, Emmanuel; Ferraro, Simone; Amodeo, Stefania; Battaglia, Nicholas; Aiola, Simone; Austermann, Jason E.; Beall, James A.; Bean, Rachel; Becker, Daniel T.; Bond, Richard J.; Calabrese, Erminia; Calafut, Victoria; Choi, Steve K.; Denison, Edward V. (15 March 2021). "Atacama Cosmology Telescope: Combined kinematic and thermal Sunyaev-Zel'dovich measurements from BOSS CMASS and LOWZ halos". Physical Review D. 103 (6): 063513. arXiv: 2009.05557 . doi:10.1103/PhysRevD.103.063513.
  14. ↑ Atacama Cosmology Telescope Collaboration; Schaan, Emmanuel; Ferraro, Simone; Amodeo, Stefania; Battaglia, Nicholas; Aiola, Simone; Austermann, Jason E.; Beall, James A.; Bean, Rachel; Becker, Daniel T.; Bond, Richard J.; Calabrese, Erminia; Calafut, Victoria; Choi, Steve K.; Denison, Edward V. (15 March 2021). "Atacama Cosmology Telescope: Combined kinematic and thermal Sunyaev-Zel'dovich measurements from BOSS CMASS and LOWZ halos". Physical Review D. 103 (6): 063513. arXiv: 2009.05557 . doi:10.1103/PhysRevD.103.063513.
  15. ↑ Naess, Sigurd; Aiola, Simone; Battaglia, Nick; Bond, Richard J.; Calabrese, Erminia; Choi, Steve K.; Cothard, Nicholas F.; Halpern, Mark; Hill, J. Colin; Koopman, Brian J.; Devlin, Mark; McMahon, Jeff; Dicker, Simon; Duivenvoorden, Adriaan J.; Dunkley, Jo (1 December 2021). "The Atacama Cosmology Telescope: A Search for Planet 9". The Astrophysical Journal. 923 (2): 224. arXiv: 2104.10264 . doi: 10.3847/1538-4357/ac2307 . ISSN   0004-637X.
  16. ↑ Fowler, J.; et al. (2007). "Optical Design of the Atacama Cosmology Telescope and the Millimeter Bolometric Array Camera". Applied Optics . 46 (17): 3444–54. arXiv: astro-ph/0701020 . Bibcode:2007ApOpt..46.3444F. doi:10.1364/AO.46.003444. PMID   17514303. S2CID   10833374.
  17. ↑ "ACT public webpage".
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