The Cosmic Background Imager: Conference Presentations

Cosmic Background Imager

Conference Presentations and Theses

Abstracts from Smithsonian/NASA ADS Astronomy Abstract Service

Title:		Interferometric polarimetry of the cosmic microwave background: Methodology
Authors:		Myers, S. T.; Sievers, J. L.; Bond, J. R.; Contaldi, C. R.; Mason, B. S.; Pearson, T. J.; Readhead, A. C. S.
Affiliation:		AA(National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, United States), AB(Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, Ont., Canada M5S 3H8), AC(Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, Ont., Canada M5S 3H8), AD(Theoretical Physics, Blackett Laboratory, Imperial College, London SW7 2BZ, UK), AE(National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, United States), AF(Astronomy, Caltech 105-24, Pasadena, CA 91125, United States), AG(Astronomy, Caltech 105-24, Pasadena, CA 91125, United States)
Publication:		New Astronomy Reviews, Volume 50, Issue 11-12, p. 951-959. (NewAR Homepage)
Publication Date:		12/2006
Origin:		ELSEVIER
Abstract Copyright:		Elsevier B.V.
DOI:		10.1016/j.newar.2006.09.025
Bibliographic Code:		2006NewAR..50..951M

Abstract

Interferometry has long been used in radio astronomy to enable imaging of astronomical sources with angular resolutions exceeding the diffraction limit of a single aperture. In the past decade, interferometry of the CMB has been carried out with instruments such as the CBI, DASI and VSA which exploited the inherent instrumental stability and simplicity of ell-space analysis of interferometer data. The practice of interferometric polarimetry has been particularly well-developed in the radio astronomical community and DASI and CBI were able to measure the polarization of the CMB over the multipole range 200 < l < 1500. In this talk, I discuss the theory of interferometry and the mathematics of CMB interferometric polarimetry, using the recent polarization observations of the Cosmic Background Imager (CBI) as an example. Topics will also include description of the data pipeline, handling of contaminating signals and sources, and the construction of optimal maps. I will conclude with the possibility of future CMB interferometers with kilo-element arrays and mega-pixel imaging.

Title:		Polarization Spectrum of CMB Obtained from the Cosmic Background Imager
Authors:		Reeves, R. A.; Bustos, R.; Torres, S.; Readhead, A.
Affiliation:		AA(Departamento de Ingeniería Eléctrica, Universidad de Concepción, Concepción, Chile.)
Publication:		XI IAU Regional Latin American Meeting of Astronomy (Eds. L. Infante & M. Rubio) Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) Vol. 26, pp. 121-122 (2006) (RMxAC Homepage)
Publication Date:		06/2006
Origin:		RMXAA
Keywords:		Cosmic Microwave Background, Cosmology: Observations
Abstract Copyright:		(C) 2006; Instituto de Astronomía, Universidad Nacional Autónoma de México
Bibliographic Code:		2006RMxAC..26..121R

Abstract

We present the estimated angular power spectrum of the polarized CMB emission by using the Cosmic Background Imager (CBI). Dedicated CMB observations were carried out from September 2002 to April 2005, providing enough data to extract an unprecedent EE power spectrum with an overall 10sigma detection of polarization. The peak-dip pattern of the EE spectrum and its phase shift with the TT power spectrum confirm important aspects of the primordial physics of the early universe as inferred from the standard cosmological model.

Title:		The High-ell Excess In The CBI CMB Power Spectrum
Authors:		Sievers, Jonathan L.; CBI Collaboration
Affiliation:		AA(CITA, Canada), AB()
Publication:		American Astronomical Society Meeting 208, #27.04
Publication Date:		06/2006
Origin:		AAS
Abstract Copyright:		(c) 2006: American Astronomical Society
Bibliographic Code:		2006AAS...208.2704S

Abstract

Unexpectedly high power is observed in the Cosmic Microwave Background power spectrum on small angular scales (ell> 2000). Complementary optical and radio measurements should help constrain the source of the excess. We discuss the current state and follow-up observations of the high-ell excess, focusing in particular on data from the Cosmic Background Imager and follow-up data taken with the Canada-France-Hawaii telescope and the Green Bank Telescope.

Title:		A New Radio Emission Mechanism in the ISM
Authors:		Casassus, S.
Publication:		The Cool Universe: Observing Cosmic Dawn, ASP Conference Series, Vol. 344, Proceedings of the conference held 4-8 October, 2004 in Valparaiso, Chile. Edited by C. Lidman and D. Alloin. San Francisco: Astronomical Society of the Pacific, 2005., p.140
Publication Date:		12/2005
Origin:		ASP
Bibliographic Code:		2005ASPC..344..140C

Abstract

A byproduct of experiments designed to map the CMB is the recent detection of a new component of foreground Galactic emission. The anomalous foreground at 10--30 GHz, unexplained by traditional emission mechanisms, correlates with 100 micron dust emission, and is thus presumably due to dust.

Is the anomalous foreground ubiquitous in the Galaxy? We present evidence obtained with the CBI experiment supporting the existence of the new component in specific objects, in the form of a 31 GHz excess over free-free emission in H II regions, planetary nebulae, and a surprisingly radio-bright dark cloud.

Title:		The CBI Project and Latest Results
Authors:		Bustos, R.
Publication:		The Cool Universe: Observing Cosmic Dawn, ASP Conference Series, Vol. 344, Proceedings of the conference held 4-8 October, 2004 in Valparaiso, Chile. Edited by C. Lidman and D. Alloin. San Francisco: Astronomical Society of the Pacific, 2005., p.37
Publication Date:		12/2005
Origin:		ASP
Bibliographic Code:		2005ASPC..344...37B

Abstract

The CBI (Cosmic Background Imager) has been operating since 1999 on the Chajnantor Plateau in the 2nd region of Chile. In 2000, the CBI obtained the first high-resolution image of the anisotropies of the CMB that correspond to the seeds that gave rise to clusters of galaxies. Since 2002, the CBI has been observing polarization of the CMB, obtaining the first polarization spectrum. Here we outline the main aspects of the CBI telescope and present some recent results.

Title:		CMB Foreground Surveys with the New Sensitive Wideband Continuum Backend on the Green Bank Telescope
Authors:		Mason, B.; Weintraub, L.; Pearson, T.; Sievers, J.; Shepherd, M.; Readhead, A.
Affiliation:		AA(NRAO), AB(Caltech), AC(Caltech), AD(CITA), AE(Caltech), AF(Caltech)
Publication:		American Astronomical Society Meeting 207, #170.13; Bulletin of the American Astronomical Society, Vol. 37, p.1429
Publication Date:		12/2005
Origin:		AAS
Abstract Copyright:		(c) 2005: American Astronomical Society
Bibliographic Code:		2005AAS...20717013M

Abstract

The California Institute of Technology and the National Radio Astronomy Observatory have constructed a new continuum backend for use with the 26 to 40 GHz pseudo-correlation receiver on the Green Bank Telescope (GBT). The backend simultaneously measures RF power across the full 14 GHz receiver band in two feeds and two polarizations, and is capable of executing a rapid beam switch to suppress the effects of receiver gain fluctuations. Combined with the GBT's large and excellent surface the CCB will give unprecedented cm-wave sensitivity to study CMB discrete-source foregrounds and very small-scale anisotropies. We present an overview of the instrument and our early science program, which aims to more precisely measure the small-scale excess power seen by the Cosmic Background Imager.

Title:		Results of CMB Observations with the Cosmic Background Imager
Authors:		Sievers, J.; CBI Collaboration
Affiliation:		AA(CITA)
Publication:		American Astronomical Society Meeting 207, #100.07; Bulletin of the American Astronomical Society, Vol. 37, p.1329
Publication Date:		12/2005
Origin:		AAS
Abstract Copyright:		(c) 2005: American Astronomical Society
Bibliographic Code:		2005AAS...20710007S

Abstract

The CBI is a 13-element interferometer operating between 26 and 36 GHz at an altitude of 5080 meters in the Chilean Andes, covering a range in l between 400 and 3500. It has been observing the Cosmic Microwave Background since January 2000, and in a polarization-optimized configuration since September 2002. We discuss the latest results from CBI observations of the CMB in total intensity and polarization, including the most significant detection of CMB E-mode polarization to date, and their cosmological implications. When the CBI EE spectrum is combined with the lower-l DASI and Boomerang EE spectra, the angular scale of the power spectrum is determined to better than 3 independendent of TT measurements, a powerful consistency check on the standard model. The polarization data are consistent with adiabatic-only fluctuations, and are highly inconsistent with models that grossly modify the heights or locations of the Doppler peaks, such as would happen if there were significant isocurvature fluctuations.

This work is supported by NSERC, the Canadian Institute for Advance Research, the NSF, Barbara and Stanley Rawn, Jr., Rochus Vogt, and Oxford University

Title:		Galactic Observations with the CBI
Authors:		Dickinson, C.; Caltech Collaboration; Oxford U. (UK) Collaboration; U. Manchester (UK) Collaboration; U. Chile Collaboration
Affiliation:		AA(California Institute of Technology)
Publication:		American Astronomical Society Meeting 207, #53.06; Bulletin of the American Astronomical Society, Vol. 37, p.1237
Publication Date:		12/2005
Origin:		AAS
Abstract Copyright:		(c) 2005: American Astronomical Society
Bibliographic Code:		2005AAS...207.5306D

Abstract

The CBI allows imaging, in both total intensity and polarization, of a wide range of Galactic phenomena on angular scales of 5-30 arcmin, in the relatively unexplored frequency range 26-36 GHz. We have made observations of a variety of objects and regions in the Galaxy; these include molecular dust clouds, supernova remnants and HII regions. By utilizing 10 1-GHz channels and polarization imaging capability we investigate the nature of the Galactic emissions (synchrotron and free-free emission) and in particular, the anomalous dust-correlated emission whose origin remains elusive. Detailed comparisons are made with multi-frequency data to provide further spectral and morphological information on the diffuse Galactic emissions which are important CMB foregrounds, particularly for polarization studies. The relevance of these results for current and future CMB experiments is discussed.

This work is supported by the NSF, Barbara and Stanley Rawn, Jr., Rochus Vogt, Oxford University and Manchester University.

Title:		Observations of the Sunyaev-Zel'dovich effect using the CBI
Authors:		Taylor, A. C.; CBI Collaboration
Affiliation:		AA(University of Oxford)
Publication:		American Astronomical Society Meeting 207, #41.04; Bulletin of the American Astronomical Society, Vol. 37, p.1226
Publication Date:		12/2005
Origin:		AAS
Abstract Copyright:		(c) 2005: American Astronomical Society
Bibliographic Code:		2005AAS...207.4104T

Abstract

The Cosmic Background Imager (CBI) is an interferometer primarily designed to image primordial temperature and polarization anisotropies in the cosmic microwave background (CMB) on small angular scales in the frequency range 26-36 GHz. It has also been used to observe the Sunyaev-Zel'dovich (SZ) effect in galaxy clusters, and we will present recent SZ observations with the CBI. In 2006 we plan to upgrade the CBI by increasing the antenna size from 0.9 to 1.4m. As well as increasing the sensitivity to CMB fluctuations on small angular scales (l > 900), this upgrade will make the CBI much more suited to SZ observations, by both increasing the flux sensitivity and reducing the relative contamination from primordial CMB anisotropies. We will present plans to make deep SZ measurements of an X-ray flux-limited sample of clusters for which deep XMM data are also being obtained. This well-defined sample will be used to study the relationship between measured SZ fluxes and X-ray-determined masses and temperatures, and hence help to calibrate the cluster properties that will be measured by upcoming SZ surveys.

This work is supported by the NSF, Barbara and Stanley Rawn, Jr., Rochus Vogt, Oxford University and the Royal Society.

Title:		A New Component in the Radio Continua of PNe
Authors:		Casassus, S.; Nyman, L.-Å.; Pearson, T. J.; Readhead, A. C.
Affiliation:		AA(Departamento de Astronomía, Universidad de Chile, Santiago, Casilla 36-D, Chile), AB(European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Santiago 19, Chile; Onsala Space Observatory, 439 92 Onsala, Sweden), AC(Owens Valley Radio Observatory, California Institute of Technology, Pasadena, CA 91125), AD(Owens Valley Radio Observatory, California Institute of Technology, Pasadena, CA 91125)
Publication:		PLANETARY NEBULAE AS ASTRONOMICAL TOOLS: International Conference on Planetary Nebulae as Astronomical Tools. AIP Conference Proceedings, Volume 804, pp. 204-207 (2005). (AIPC Homepage)
Publication Date:		11/2005
Origin:		STI
NASA/STI Keywords:		planetary nebulae, radiosources (astronomical), Galaxy
Abstract Copyright:		(c) 2005: American Institute of Physics
DOI:		10.1063/1.2146273
Bibliographic Code:		2005AIPC..804..204C

Abstract

A byproduct of experiments designed to map the CMB is the recent detection of a new component of foreground galactic emission. The anomalous foreground at 10-30 GHz, unexplained by traditional emission mechanisms, correlates with 100 mum dust emission, and is thus presumably due to dust.

Is the anomalous foreground ubiquitous in the Galaxy? I will present evidence obtained with the CBI and SIMBA+SEST supporting the existence of the new component in the ISM at large, and in specific objects, in the form of a 31 GHz excess over free-free emission in PNe.

Title:		The Sunyaev-Zeldovich Effect Imaging and Interferometry: BIMA-CBI-OVRO State of the Art and Future Prospects
Authors:		Myers, Steven T.
Publication:		New Cosmological Data and the Values of the Fundamental Parameters, Proceedings of IAU Symposium #201, held 7-11 August 2000 at Manchester, United Kingdom. Edited by A. Lasenby and A. Wilkinson. San Francisco, CA: Astronomical Society of the Pacific (ASP), 2005., p.219
Publication Date:		00/2005
Origin:		ADS
Bibliographic Code:		2005IAUS..201..219M

Abstract

Not Available

Title:		The Cosmic Background Imager
Authors:		Pearson, T. J.; Mason, B. S.; Padin, S.; Readhead, A. C. S.; Shepherd, M. C.; Sievers, J.; Udomprasert, P. S.; Cartwright, J. K.
Publication:		New Cosmological Data and the Values of the Fundamental Parameters, Proceedings of IAU Symposium #201, held 7-11 August 2000 at Manchester, United Kingdom. Edited by A. Lasenby and A. Wilkinson. San Francisco, CA: Astronomical Society of the Pacific (ASP), 2005., p.23
Publication Date:		00/2005
Origin:		ADS
Bibliographic Code:		2005IAUS..201...23P

Abstract

Not Available

Title:		Data analysis of and results from observations of the cosmic microwave background with the Cosmic Background Imager
Authors:		Sievers, Jonathan Leroy
Affiliation:		California Institute of Technology, United States -- California
Publication:		Ph.D dissertation, 2004. 155 pages; United States -- California: California Institute of Technology; 2004. Publication Number: AAT 3151388. DAI-B 65/10, p. 5191, Apr 2005
Publication Date:		12/2004
Category:		Astronomy, Astrophysics
Origin:		UMI
Keywords:		Cosmic microwave background, Cosmic Background Imager, Power spectrum, Hubble constant
Comment:		Publication Number: AAT 3151388; ISBN: 0496114530; Advisor: Readhead, Anthony
Bibliographic Code:		2004PhDT........30S

Abstract

We present results from observations of the Cosmic Microwave Background (CMB) with the Cosmic Background Imager (CBI), a sensitive 13-element interferometer located high in the Chilean Andes. We also discuss methods of analyzing the data from the CBI, including an improved way of measuring the true power spectrum using maximum likelihood estimation. This improved method leads to a saving of a factor of two in memory usage, and an increase in speed of order the number of points in the spectrum. The initial results are discussed, in which the fall-off in power at ell > 1000 (the "damping tail") was first observed. We also present the results from the first year of observations with the CBI, and discuss cosmological interpretations both alone and in concert with the results from other experiments. These provide tight constraints on cosmological parameters, including a Hubble constant of 69 +/- 4 km/s/Mpc, an age of the universe of 13.7 +/- 0.2 billion years, and a density of dark energy of 0.70 +/- 0.05 of the critical density of the universe. Finally, we discuss an alternate method of data compression, with great flexibility in what information is kept, while being computationally tractable. We then apply this method to the CBI data to constrain the potential emission from foreground contaminants contributing to the observed CMB radiation. We find that the data is consistent with zero foreground, with a maximum allowed foreground contribution between about 8% and 12% of the total signal (at an ell of 600 and frequency of 30 GHz), depending on the spectral index of foreground emission.

Title:		Implications of the CBI Polarization Spectrum
Authors:		Sievers, J. L.; CBI
Affiliation:		AA(CITA)
Publication:		American Astronomical Society Meeting 205, #73.07; Bulletin of the American Astronomical Society, Vol. 36, p.1470
Publication Date:		12/2004
Origin:		AAS
Abstract Copyright:		(c) 2004: American Astronomical Society
Bibliographic Code:		2004AAS...205.7307S

Abstract

The Cosmic Background Imager (CBI), a radio interferometer located in the Chilean Andes, has recently published a spectrum of the polarized power spectrum of the CMB in a range of l ∼ 400-2000. The CBI's polarization spectrum has sufficient sensitivity that it can begin to place limits on allowed cosmological models, independent of the total-intensity spectrum. I discuss some of these limits, including the angular scale of the polarized spectrum and the phase of the polarized spectrum relative to that predicted by the total-intensity.

Title:		CMB polarization observations with the Cosmic Background Imager
Authors:		Pearson, T. J.; CBI
Affiliation:		AA(Caltech)
Publication:		American Astronomical Society Meeting 205, #73.06; Bulletin of the American Astronomical Society, Vol. 36, p.1469
Publication Date:		12/2004
Origin:		AAS
Abstract Copyright:		(c) 2004: American Astronomical Society
Bibliographic Code:		2004AAS...205.7306P

Abstract

The Cosmic Background Imager (CBI), an interferometer operating in the 26--36 GHz band, has been making observations of the polarization of the microwave background since September 2002. The EE power spectrum of the CMB has been measured at multipoles up to l 1000, and upper limits have been placed on the EE power at 1000 < l < 2000. The spectrum is in good agreement with earlier measurements from DASI at lower l and with the predictions of standard Lambda CDM models, in which the polarization is generated by Thomson scattering during recombination. The BB power spectrum is consistent with zero as expected in the standard models. The work was supported by NSF AST-0206416.

Title:		CMB Polarization Data Analysis for the Cosmic Background Imager
Authors:		Myers, S. T.; CBI
Affiliation:		AA(NRAO)
Publication:		American Astronomical Society Meeting 205, #69.12; Bulletin of the American Astronomical Society, Vol. 36, p.1461
Publication Date:		12/2004
Origin:		AAS
Abstract Copyright:		(c) 2004: American Astronomical Society
Bibliographic Code:		2004AAS...205.6912M

Abstract

The Cosmic Background Imager (CBI) is a 13-element interferometer observing at a freqency of 26--36 GHz from the high-altitude ALMA site in Chile. Since 2002, it has observed the polarization of the cosmic microwave background (CMB) radiation. In this poster, we describe the data analysis techniques used to process the data and measure the angular power spectrum of the CMB polarization. The CBI observes in R and L circular polarizations, and the cross-correlations between these are directly related to the E and B polarization modes fundamental to cosmological model predictions for the CMB. The CBI processing pipeline employs a novel gridding scheme in the Fourier domain which optimally compresses the large number of data samples from the mosaic scanning patterns used in the CBI observations. Processing was carried out on the 512-processor McKenzie cluster at the Canadian Institute for Theoretical Astrophysics.

Title:		The Hubble Constant Derived from the Sunyaev-Zel'dovich Effect
Authors:		Stilp, A. M.; Myers, S. T.
Affiliation:		AA(University of Wisconsin-Madison/NRAO), AB(NRAO)
Publication:		American Astronomical Society Meeting 205, #69.07; Bulletin of the American Astronomical Society, Vol. 36, p.1460
Publication Date:		12/2004
Origin:		AAS
Abstract Copyright:		(c) 2004: American Astronomical Society
Bibliographic Code:		2004AAS...205.6907S

Abstract

One powerful way to determine the distance to galaxy clusters is the combination of the Sunyaev-Zel'dovich Effect (SZE) with thermal bremsstrahlung from hot gas in the intracluster medium. This technique allows a measurement independent of the cosmic distance ladder. We will present an analysis of two low redshift (z < 0.1) galaxy clusters, A3266 and A3558, using the above method. By combining SZE observations from the Cosmic Background Imager (CBI) with results of previously-published X-ray data, we fit models of cluster gas structure to the data using both a maximum likelihood method and a Markov Chain Monte Carlo (MCMC) algorithm. The best-fit models yield a measurement of distance to the galaxy clusters, and a value for H₀ can be calculated from the best-fit distances and published redshift data. We obtained a result of H₀ = 65±14 km s^-1 Mpc^-1 as an average of the H₀ values for each cluster, which is consistent with the value of 72±5 km s^-1 Mpc^-1 measured by WMAP. We will discuss the application of the MCMC algorithm to SZE and X-ray data as well as display the results of our own analysis using this technique. This work was supported by a NSF-REU site grant to Associated Universities, Inc./National Radio Astronomy Observatories.

Title:		Cosmic Background Imager Observations of the Temperature and Polarization of the CMB
Authors:		Myers, S. T.; CBI Collaboration
Affiliation:		AA(NRAO)
Publication:		American Astronomical Society Meeting 204, #91.07; Bulletin of the American Astronomical Society, Vol. 36, p.822
Publication Date:		05/2004
Origin:		AAS
Abstract Copyright:		(c) 2004: American Astronomical Society
Bibliographic Code:		2004AAS...204.9107M

Abstract

The Cosmic Background Imager (CBI) is an interferometer dedicated to observations of the Cosmic Microwave Background (CMB). The CBI has 13 90-cm antennas mounted on a 5.5-m platform and observes in the band 26-36 GHz from the Chilean Andes near San Pedro de Atacama (alt. 5000m). The CBI has been in operation since 1999, and has produced measurements of the CMB temperature angular power spectrum as reported in previous publications, as well as observations of the Sunyaev-Zeldovich Effect in nearby clusters of galaxies. Since September 2002, the CBI has been operating in a configuration optimized for CMB polarization observations. We present the most recent CBI results on the temperature and polarization angular power spectra, and discuss the implications for the determination of cosmological parameters and the discrimination between cosmological models. Comparison and combination with other CMB observations is also presented. The CBI is funded by the National Science Foundation, along with the generous support of the CBI team home institutions.

Title:		H(0) from Cosmic Background Imager observations of the Sunyaev-Zel'dovich effect in nearby clusters
Authors:		Udomprasert, Patricia Simcoe
Affiliation:		California Institute of Technology, United States -- California
Publication:		Ph.D dissertation, 2004. 115 pages; United States -- California: California Institute of Technology; 2004. Publication Number: AAT 3151394. DAI-B 65/10, p. 5192, Apr 2005
Publication Date:		00/2004
Category:		Astronomy, Astrophysics
Origin:		UMI
Keywords:		Hubble constant, Cosmic Background Imager, Sunyaev- Zel'dovich effect, Galaxy clusters, Cosmology
Comment:		Publication Number: AAT 3151394; ISBN: 049611459X; Advisor: Readhead, Anthony C. S.
Bibliographic Code:		2004PhDT.........3U

Abstract

We present H 0 results from Cosmic Background Imager (CBI) observations of the Sunyaev-Zel'dovich Effect (SZE) in 7 galaxy clusters, A85, A399, A401, A478, A754, A1651, and A2597. These observations are part of a program to study a complete, volume-limited sample of low-redshift ( z < 0.1), X-ray selected clusters. Our focus on nearby objects allows us to study a well-defined, orientation-unbiased sample, minimizing systematic errors due to cluster asphericity. We use density models derived from ROSAT imaging data and temperature measurements from ASCA and BeppoSAX spectral observations. We quantify in detail sources of error in our derivation of H 0 , including calibration of the CBI data, density and temperature models from the X-ray data, Cosmic Microwave Background (CMB) primary anisotropy fluctuations, and residuals from radio point source subtraction. From these 7 clusters we obtain a result of H 0 = [Special characters omitted.] km s -1 Mpc -1 for an unweighted sample average. The respective quoted errors are random and systematic uncertainties at 68% confidence. The dominant source of error is confusion from intrinsic anisotropy fluctuations. We present results from simulations of an eigenmode weighting analysis that reduce the uncertainties due to CMB in h -1/2 by ~30%.

Title:		New Results &Current Work with the CBI
Authors:		Mason, Brian S.
Publication:		Multiwavelength Cosmology. Proceedings of the "Multiwavelength Cosmology" conference, held on Mykonos Island, Greece, 17-20 June, 2003. Edited by Manolis Plionis. ASTROPHYSICS AND SPACE SCIENCE LIBRARY Volume 301. ISBN 1-4020-1971-8 (HB); ISBN 0-306-48570-2 (e-book). Published by Kluwer Academic Publishers, Dordrecht, The Netherlands, 2004, p.85
Publication Date:		00/2004
Origin:		ADS
Bibliographic Code:		2004muco.conf...85M

Abstract

Not Available

Title:		Interferometric Observations of the Cosmic Microwave Background Radiation
Authors:		Readhead, Anthony C. S.; Pearson, Timothy J.
Affiliation:		AA(California Institute of Technology), AB(California Institute of Technology)
Publication:		Measuring and Modeling the Universe, from the Carnegie Observatories Centennial Symposia. Published by Cambridge University Press, as part of the Carnegie Observatories Astrophysics Series. Edited by W. L. Freedman, 2004, p. 349.
Publication Date:		00/2004
Origin:		AUTHOR
Bibliographic Code:		2004mmu..symp..349R

Abstract

Radio interferometers are well suited to studies of both total intensity and polarized intensity fluctuations of the cosmic microwave background radiation, and they have been used successfully in measurements of both the primary and secondary anisotropy. Recent observations with the Cosmic Background Imager operating in the Chilean Andes, the Degree Angular Scale Interferometer operating at the South Pole, and the Very Small Array operating in Tenerife have probed the primary anisotropy over a wide range of angular scales. The advantages of interferometers for microwave background observations of both total intensity and polarized radiation are discussed, and the cosmological results from these three instruments are presented. The results show that, subject to a reasonable value for the Hubble constant, which is degenerate with the geometry in closed models, the geometry of the Universe is flat to high precision (∼5%) and the primordial fluctuation spectrum is very close to the scale-invariant Harrison-Zel'dovich spectrum. Both of these findings are concordant with inflationary predictions. The results also show that the baryonic matter content is consistent with that found from primordial nucleosynthesis, while the cold dark matter component can account for no more than ∼40 % of the energy density of the Universe. It is a requirement of these observations, therefore, that ∼60% of the energy content of the Universe is not related to matter, either baryonic or nonbaryonic. This dark energy component of the energy density is attributed to a nonzero cosmological constant.

Title:		Modeling of the Contamination of the Cosmic Background by Radio Sources
Authors:		Flores, R. M.; Mason, B. S.; CBI Collaboration
Affiliation:		AA(Barnard College/Columbia University), AB(National Radio Astronomy Observatory)
Publication:		American Astronomical Society Meeting 203, #82.01; Bulletin of the American Astronomical Society, Vol. 35, p.1333
Publication Date:		12/2003
Origin:		AAS
Abstract Copyright:		(c) 2003: American Astronomical Society
Bibliographic Code:		2003AAS...203.8201F

Abstract

Observations of the Cosmic Microwave Background (CMB) with the Cosmic Background Imager (CBI) have revealed radio foreground signals that limit the accuracy of measurements of the anisotropic properties of the CMB such as the Sunyaev-Zeldovich Effect. By comparing CBI data to NVSS (and PMN) data, accurate counts of the number of radio sources in low redshift galaxy clusters were made. It was determined that at 30 GHz there are 1.4 ± 0.3 sources per square degree brighter than 30mJy in fields containing galaxy clusters. Comparing these results to the number of radio sources at random in the sky at 30GHz (Mason et al.) a 1.38 sigma difference was found. We therefore do not detect a strong difference in the number of radio sources at 30GHz in galaxy cluster fields. This work was done in collaboration with the Cosmic Background Imager project and with the support of the National Science Foundation and the California Institute of Technology.

Title:		Elimination of confusing sources in Cosmic Background Imager fields
Authors:		Angelakis, E.; Zensus, A.; Krichbaum, T.; Kraus, A.; Readhead, A.; Pearson, T.; Bustos, R.; Reeves, R.
Publication:		Proceedings of the Second ENIGMA Meeting, held at Porto Venere, Italy, October 11-15, 2003, Eds.: C. M. Raiteri and M. Villata, Osservatorio Astronomico di Torino, Pino Torinese, Italy, p. 70-79.
Publication Date:		11/2003
Origin:		AUTHOR
Bibliographic Code:		2003enig.conf...70A

Abstract

Not Available

Title:		Humidity above the Jovian NH3 Clouds from Radio Measurements near 1 cm
Authors:		Hofstadter, M.; Readhead, T.; Gulkis, S.; Reeves, R.
Affiliation:		AA(JPL), AB(Caltech), AC(JPL), AD(Univ. de Concepcion)
Publication:		American Astronomical Society, DPS meeting #35, #48.07; Bulletin of the American Astronomical Society, Vol. 35, p.1014
Publication Date:		05/2003
Origin:		AAS
Abstract Copyright:		(c) 2003: American Astronomical Society
Bibliographic Code:		2003DPS....35.4807H

Abstract

The Cosmic Background Imager (CBI) is an interferometer working in the 26 to 36 GHz range (0.8 to 1.2 cm). Located in the Chilean Andes at an altitude of 16,700 feet, it was designed for cosmological studies of the cosmic microwave background. We have used the CBI to make precise measurements of Jupiter's total flux at radio wavelengths. By tieing CBI measurements to those of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, we have obtained absolute radiances with a 1-sigma uncertainty of +-1.3%. Relative temperatures within the above frequency range are accurate to +-0.6%.

Jupiter's spectrum at these wavelengths is dominated by the strong NH3 inversion band. The CBI data, sampling the wings of this absorption band, sound the atmosphere in the region of the assumed NH3 cloud, near 1 bar. Preliminary analysis indicates the globally averaged relative humidity of NH3 above its cloud base is in the 30 to 75% range. Uncertainty in our knowledge of the ammonia lineshape contributes as much to this spread as the uncertainty in the data. This result is in qualitative agreement with earlier work (for example, Klein and Gulkis 1978, Icarus 35; Fouchet et al. 2000, Icarus 143; de Pater et al. 2001, Icarus 149). At the meeting, we will present our analysis of CBI and WMAP data. These data provide some of the strongest constraints to date on the global behavior of ammonia in its cloud-forming region.

Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Title:		New Results from the Cosmic Background Imager
Authors:		Mason, B. S.; CBI Collaboration
Affiliation:		AA(NRAO)
Publication:		American Astronomical Society Meeting 202, #54.05; Bulletin of the American Astronomical Society, Vol. 35, p.773
Publication Date:		05/2003
Origin:		AAS
Abstract Copyright:		(c) 2003: American Astronomical Society
Bibliographic Code:		2003AAS...202.5405M

Abstract

The Cosmic Background Imager (CBI) has led in the push to small angular scale measurements of the microwave background. New results from the CBI improve the constraints at high L as well as yielding better resolution at low L. I discuss these results and current activities, including the CBI polarization observing campaign.

Title:		The Cosmic Microwave Background & Inflation, Then & Now
Authors:		Bond, J. Richard; Contaldi, Carlo; Pogosyan, Dmitry; Mason, Brian; Myers, Steve; Pearson, Tim; Pen, Ue-Li; Prunet, Simon; Readhead, Tony; Sievers, Jonathan
Affiliation:		AA(CIAR Cosmology Program, Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, Canada), AB(CIAR Cosmology Program, Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, Canada), AC(Physics Department, University of Alberta, Edmonton, Alberta, Canada), AD(Astronomy Department, California Institute of Technology, Pasadena, California; National Radio Astronomy Observatory, Socorro, New Mexico), AE(National Radio Astronomy Observatory, Socorro, New Mexico), AF(Astronomy Department, California Institute of Technology, Pasadena, California), AG(CIAR Cosmology Program, Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, Canada), AH(Institut d' Astrophysique de Paris, Paris, France; CIAR Cosmology Program, Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, Canada), AI(Astronomy Department, California Institute of Technology, Pasadena, California), AJ(Astronomy Department, California Institute of Technology, Pasadena, California)
Publication:		THEORETICAL PHYSICS: MRST 2002: A Tribute to George Leibbrandt. AIP Conference Proceedings, Volume 646, pp. 15-33 (2002). (AIPC Homepage)
Publication Date:		12/2002
Origin:		STI
Keywords:		cosmology, radiofrequency cosmic radiation, supernovae, fluctuations, spectra, dark matter, equations of state, acceleration
Abstract Copyright:		(c) 2002: American Institute of Physics
Bibliographic Code:		2002AIPC..646...15B

Abstract

The most recent results from the Boomerang, Maxima, DASI, CBI and VSA CMB experiments significantly increase the case for accelerated expansion in the early universe (the inflationary paradigm) and at the current epoch (dark energy dominance). This is especially so when combined with data on high redshift supernovae (SN1) and large scale structure (LSS), encoding information from local cluster abundances, galaxy clustering, and gravitational lensing. There are ``7 pillars of Inflation'' that can be shown with the CMB probe, and at least 5, and possibly 6, of these have already been demonstrated in the CMB data: (1) the effects of a large scale gravitational potential, demonstrated with COBE/DMR in 1992-96 (2) acoustic peaks/dips in the angular power spectrum of the radiation, which tell about the geometry of the Universe, with the large first peak convincingly shown with Boomerang and Maxima data in 2000, a multiple peak/dip pattern shown in data from Boomerang and DASI (2nd, 3rd peaks, first and 2nd dips in 2001) and from CBI (2nd, 3rd, 4th, 5th peaks, 3rd, 4th dips at 1-sigma in 2002) (3) damping due to shear viscosity and the width of the region over which hydrogen recombination occurred when the universe was 400000 years old (CBI 2002) (4) the primary anisotropies should have a Gaussian distribution (be maximally random) in almost all inflationary models, the best data on this coming from Boomerang; (5) secondary anisotropies associated with nonlinear phenomena subsequent to 400000 years, which must be there and may have been detected by CBI and another experiment, BIMA. Showing the 5 ``pillars'' involves detailed confrontation of the experimental data with theory; e.g., (5) compares the CBI data with predictions from two of the largest cosmological hydrodynamics simulations ever done. DASI, Boomerang and CBI in 2002, AMiBA in 2003, and many other experiments have the sensitivity to demonstrate the next pillar, (6) polarization, which must be there at the ~ 7% level. A broad-band DASI detection consistent with inflation models was just reported. A 7th pillar, anisotropies induced by gravity wave quantum noise, could be too small to detect. A minimal inflation parameter set, {omegab, omegacdm, Omegatot, OmegaQ, wQ, ns, tauC, sigma8}, is used to illustrate the power of the current data. After marginalizing over the other cosmic and experimental variables, we find the current CMB+LSS+SN1 data give Omegatot = 1.00_-.03^+.07, consistent with (non-baroque) inflation theory. Restricting to Omegatot = 1, we find a nearly scale invariant spectrum, ns = 0.97_-.05^+.06. The CDM density, omegacdm = Omegacdmh² = .12_-.01^+.01, and baryon density, omegab ≡ Omegabh² = .022_-.002^+.003, are in the expected range. (The Big Bang nucleosynthesis estimate is 0.019 +/- 0.002.) Substantial dark (unclustered) energy is inferred, OmegaQ ~ 0.68 +/- 0.05, and CMB+LSS OmegaQ values are compatible with the independent SN1 estimates. The dark energy equation of state, crudely parameterized by a quintessence-field pressure-to-density ratio wQ, is not well determined by CMB+LSS (wQ < -0.4 at 95% CL), but when combined with SN1 the resulting wQ < -0.7 limit is quite consistent with the wQ=-1 cosmological constant case.

Title:		Data Analysis and Cosmology with the Cosmic Background Imager
Authors:		Sievers, J. L.; CBI Collaboration
Affiliation:		AA(Caltech)
Publication:		American Astronomical Society, 201st AAS Meeting, #101.02; Bulletin of the American Astronomical Society, Vol. 34, p.1269
Publication Date:		12/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...20110102S

Abstract

The Cosmic Microwave Background has become one of our fundamental tools for understanding the global properties of the universe. It has already yielded high-precision cosmological results, with the promise of even more to come. The brute force CMB analysis methods are computationally prohibitive for all but the simplest experiments, so we have developed new analysis methods for use on interferometric microwave background data. We apply these methods to the data from the Cosmic Background Imager (CBI) to obtain a power spectrum, and, both alone and in concert with other experiments, use the power spectrum to measure fundamental cosmological parameters. The CBI is a very sensitive 13-element interferometer located at 16,700 feet in northern Chile that has provided the highest resolution measurements yet of primary CMB anisotropies.

Title:		Measuring H₀ through observations of the Sunyaev-Zeldovich Effect in Nearby Clusters with the Cosmic Background Imager
Authors:		Udomprasert, P. S.; Mason, B. S.; Readhead, A. C. S.
Affiliation:		AA(Caltech), AB(Caltech), AC(Caltech)
Publication:		American Astronomical Society, 201st AAS Meeting, #23.02; Bulletin of the American Astronomical Society, Vol. 34, p.1142
Publication Date:		12/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...201.2302U

Abstract

We present results from the Cosmic Background Imager's program to measure H₀ with 10% accuracy through observations of the Sunyaev-Zeldovich Effect in a complete sample of nearby (z<0.1) clusters. We describe our sample selection and discuss the advantages and disadvantages of studying low-z clusters over those at higher z. The results we present here utilize density models and isothermal temperatures from ROSAT, ASCA, and BeppoSAX observations. We discuss possible errors from assuming isothermal cluster gas, and we show how accurate temperature profiles from current X-ray missions can improve the H₀ measurements. We also quantify other sources of error such as observational noise, CMB primary anisotropy fluctuations, radio point sources, and cluster asphericity.

Title:		High Power in the CMB Power Spectrum from CBI Measurements at ell > 2000:
Authors:		Sievers, Jonathan
Affiliation:		Caltech
Publication:		Presented at the KITP Conference: The New Cosmology Confronts Observation, Aug 20, 2002, Kavli Institute for Theoretical Physics, University of California, Santa Barbara
Publication Date:		08/2002
Origin:		KITP
Bibliographic Code:		2002ncco.confE..34S

Abstract

Not Available

Title:		CBI, primary anisotropies
Authors:		Readhead, Anthony; Myers, Steve
Affiliation:		Caltech, NRAO
Publication:		Presented at the KITP Conference: The New Cosmology Confronts Observation, Aug 19, 2002, Kavli Institute for Theoretical Physics, University of California, Santa Barbara
Publication Date:		08/2002
Origin:		KITP
Bibliographic Code:		2002ncco.confE..32R

Abstract

Not Available

Title:		Power Spectrum of the Cosmic Microwave Background Radiation from the Cosmic Background Imager
Authors:		Pearson, T. J.; Cosmic Background Imager Collaboration
Affiliation:		AA(Caltech)
Publication:		American Astronomical Society, 200th AAS Meeting, #06.06; Bulletin of the American Astronomical Society, Vol. 34, p.949
Publication Date:		06/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...200.0606P

Abstract

The Cosmic Background Imager (CBI) is an interferometer array designed to measure the power spectrum of fluctuations in the cosmic microwave background radiation. The CBI is located at an altitude of 5080 m in northern Chile. It consists of 13 0.9-m diameter antennas on a 6-m diameter tracking platform. Each antenna has a cooled, low-noise receiver operating in the 26--36 GHz band. Signals are cross-correlated in an analog correlator with 10 1-GHz bands. We describe the observations and data-analysis methods and present a determination of the microwave background intrinsic anisotropy spectrum over the range l=400 to l=3500. The CBI project is supported by the NSF.

Title:		Polarization observations with the Cosmic Background Imager
Authors:		Cartwright, John K.; Readhead, Anthony C. S.; Shepherd, Martin C.; Padin, Steve; Pearson, Timothy J.; Taylor, Greg B.
Affiliation:		AA(Department of Astronomy, California Institute of Technology, Pasadena, California 91125), AB(Department of Astronomy, California Institute of Technology, Pasadena, California 91125), AC(Department of Astronomy, California Institute of Technology, Pasadena, California 91125), AD(Department of Astronomy, California Institute of Technology, Pasadena, California 91125), AE(Department of Astronomy, California Institute of Technology, Pasadena, California 91125), AF(National Radio Astronomy Observatory, Socorro, New Mexico 87801-0387)
Publication:		EXPERIMENTAL COSMOLOGY AT MILLIMETRE WAVELENGTHS: 2K1BC Workshop. Breuil-Cervinia, Valle d'Aosta, Italy, 9-13 July, 2001. Edited by Marco De Petri and Massimo Gervasi. American Institute of Physics, 2002. AIP Conference Proceedings, Volume 616, pp. 135-139 (2002). (AIPC Homepage)
Publication Date:		05/2002
Origin:		STI
Keywords:		cosmic background radiation, radiofrequency cosmic radiation, interferometers, antenna arrays, polarisation, astronomical instruments
Abstract Copyright:		(c) 2002: American Institute of Physics
Bibliographic Code:		2002AIPC..616..135C

Abstract

We describe polarization observations of the CMBR with the Cosmic Background Imager, a 13 element interferometer which operates in the 26-36 GHz band from Llano de Chajnantour in northern Chile. The array consists of 90-cm Cassegrain antennas mounted on a steerable platform which can be rotated about the optical axis to facilitate polarization observations. The CBI employs single mode circularly polarized receivers which sample multipoles from <script>l</script>~400 to <script>l</script>~4250. The instrumental polarization of the CBI was calibrated with 3C279, a bright polarized point source which was monitored with the VLA. .

Title:		Cosmic Background Interferometry: A Fast Data-Analysis Pipeline
Authors:		Myers, S. T.; Cosmic Background Imager Collaboration
Affiliation:		AA(NRAO)
Publication:		American Astronomical Society, 200th AAS Meeting, #86.03; Bulletin of the American Astronomical Society, Vol. 34, p.787
Publication Date:		05/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...200.8603M

Abstract

A fast Fourier-plane analysis pipeline has been developed for the Cosmic Background Imager (CBI) project. The interferometer visibilities are pre-gridded into a set of estimators that are constructed on a lattice in the uv plane. The correlations between these estimators are used as the basis for a maximum likelihood reconstruction of the power spectrum of the intensity fluctuations seen on the sky. This technique has been shown to be efficient and robust, and can deal with large mosaics of fields such as those produced by interferometers measuring the Cosmic Microwave Background Radiation (CMBR) such as the CBI. This pipeline can also produce optimally filtered images from the estimators, and can deal with polarization data as well. We describe this novel method, and show results for simulated datasets as well as real results from the CBI. The scientific results highlighted include the recently released CBI deep-field and mosaic power spectra of the CMBR which cover the multipole range from l=300--3000. We also emphasize the use of the CBI pipeline for the analysis of polarization interferometry data, with particular application to the CBI polarization upgrade currently underway.

Title:		Cosmology from the latest CBI and BOOMERanG results
Authors:		Contaldi, C. R.; CBI/BOOMERanG Collaboration
Affiliation:		AA(CITA)
Publication:		American Astronomical Society, 200th AAS Meeting, #86.02; Bulletin of the American Astronomical Society, Vol. 34, p.787
Publication Date:		05/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...200.8602C

Abstract

We present the latest results from the BOOMERanG and CBI experiments which chart the angular power spectrum of the Cosmological Microwave Background anisotropies upto multipoles l = 3500 . We investigate the cosmological parameters obtained by including the new data in our parameter fits to a host of CMB datasets. We show how the CMB strongly constrains the curvature of the Universe, the baryon density and the tilt of the primordial power spectrum. We also show how including external constraints from various experiments can help to significantly constrain the density of cold dark matter and cosmological constant.

Title:		The CMB-osis of Cosmic Fluctuations
Authors:		Bond, J. R.
Affiliation:		AA(CITA)
Publication:		American Astronomical Society, 200th AAS Meeting, #83.01; Bulletin of the American Astronomical Society, Vol. 34, p.784
Publication Date:		05/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...200.8301B

Abstract

The tiny fluctuations in the 3K photon afterglow of the Big Bang are geometrical mappings of sound waves when this ``oldest light in the Universe'' decoupled from matter some 14 Gigayears ago. In work spanning two decades, my collaborators and I have shown how these encode information on the many parameters that define cosmic structure formation theory. We have developed tools to analyze the sequence of heroic experiments that have always pushed technology to the edge, from even before the COBE satellite of the early 90s through Boomerang, the Cosmic Background Imager, and other recent experiments that have now directly imaged these acoustic patterns. The patterns appear to be Gaussian-distributed and their power spectra show multiple peaks and troughs and a damping tail. Our analyses support the remarkable neo-Big-Bang paradigm: that quantum noise generated during an ultra-early accelerated expansion amplified via gravitational instability to form the galaxies and their hierarchical clustering patterns that we observe as the interconnected ``cosmic web''. When combined with precise theoretical calculations, the CMB and cosmic web data have allowed us to accurately infer the mass-energy densities in ordinary (baryonic) matter, "cold" dark matter, and "vacuum" dark energy to be about 5%, 30% and 65%, summing to ensure a nearly flat large scale geometry. The dominance of dark energy is arguably the greatest mystery in physics. A host of new high precision CMB experiments, many targeting polarization and secondary CMB processes associated with nonlinear effects, will help to establish its properties.

Title:		Cosmology with the Cosmic Microwave Background Radiation and the Sunyaev-Zel'dovich Effect
Authors:		Readhead, A. C. S.; Pearson, T. J.; Mason, B. S.; Shepherd, M. S.; Sievers, J.; Udomprasert, P. S.; Cartwright, J. K.; Padin, S.; Farmer, A.; Myers, S. T.; Bond, J. R.; Contaldi, C. R.; Pen, U.; Pogosyan, D.; Prunet, S.; Holzapfel, W. L.; Carlstrom, J. E.; Leitch, E. M.; Kovac, J.; Pryke, C.; Bronfman, L.; May, J.; Altamirano, P.; Joy, M.
Affiliation:		AA(California Institute of Technology), AB(California Institute of Technology), AC(California Institute of Technology), AD(California Institute of Technology), AE(California Institute of Technology), AF(California Institute of Technology), AG(California Institute of Technology), AH(California Institute of Technology), AI(California Institute of Technology), AJ(NRAO), AK(Canadian Institute of Theoretical Astrophysics), AL(Canadian Institute of Theoretical Astrophysics), AM(Canadian Institute of Theoretical Astrophysics), AN(Canadian Institute of Theoretical Astrophysics), AO(Canadian Institute of Theoretical Astrophysics), AP(U. C. Berkeley), AQ(University of Chicago), AR(University of Chicago), AS(University of Chicago), AT(University of Chicago), AU(Universidad de Chile), AV(Universidad de Chile), AW(Universidad de Chile), AX(Marshall Space Flight Center)
Publication:		American Astronomical Society, 200th AAS Meeting, #51.14; Bulletin of the American Astronomical Society, Vol. 34, p.726
Publication Date:		05/2002
Origin:		AAS
Abstract Copyright:		(c) 2002: American Astronomical Society
Bibliographic Code:		2002AAS...200.5114R

Abstract

Observations of the intrinsic anisotropy in the cosmic microwave background radiation (cmbr) and the scattering of cmbr photons in clusters of galaxies due to the Sunyaev-Zel'dovich Effect provide a powerful new method of measuring fundamental cosmological parameters, including the geometry of the universe, the baryonic and non-baryonic matter content of the universe, the cosmological constant, the Hubble Constant and the slope of the primordial density fluctuation spectrum. The spectacular recent successes of balloon-borne payloads and of radio interferometers in this rapidly developing field will be summarized, and new results from the Cosmic Background Imager (CBI), which has been making observations of the cmbr since January 2000 from a site at an altitude of 16,700 feet in the Chilean Andes, will be presented.

Title:		Preliminary results from the Cosmic Background Imager
Authors:		Mason, B. S.; Cartwright, J. K.; Padin, S.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M.; Sievers, J.; Udomprasert, P.
Publication:		In: The Ninth Marcel Grossmann Meeting. Proceedings of the MGIXMM Meeting held at The University of Rome "La Sapienza", 2-8 July 2000, Eds.: Vahe G. Gurzadyan, Robert T. Jantzen, Remo Ruffini. Singapore: World Scientific Publishing, in 3 volumes, ISBN 981-238-010-8 (set), ISBN 981-238-995-4 (Part A), ISBN 981-238-994-6 (Part B), ISBN 981-238-993-8 (Part C), 2002, Part C, p. 2171 - 2172
Publication Date:		00/2002
Origin:		ARI
Keywords:		Cosmic Microwave Background: Anisotropy, Observations
Abstract Copyright:		World Scientific
Bibliographic Code:		2002nmgm.meet.2171M

Abstract

The Cosmic Background Imager (CBI) is a 13-element interferometer designed to image intrinsic anisotropies in the cosmic microwave background (CMB) on arcminute scales. A review of the capabilities of the instrument is presented, together with a discussion of observations which have been taken over the past 9 months from the Atacama desert of Chile. We present preliminary high-resolution mosaiced images of the CMB obtained from recent CBI data and discuss topics which the CBI will address in the near future.

Title:		A determination of H₀ from CBI Observations of the Sunyaev-Zel'dovich Effect in Nearby Clusters
Authors:		Udomprasert, P. S.; Mason, B. S.; Readhead, A. C. S.
Affiliation:		AA(Caltech), AB(Caltech), AC(Caltech)
Publication:		American Astronomical Society, 199th AAS Meeting, #75.06; Bulletin of the American Astronomical Society, Vol. 33, p.1419
Publication Date:		12/2001
Origin:		AAS
Abstract Copyright:		(c) 2001: American Astronomical Society
Bibliographic Code:		2001AAS...199.7506U

Abstract

With the Cosmic Background Imager, a 13-element interferometer located in the Chilean Andes, we are conducting a study to determine H₀ with 10% accuracy through observations of the Sunyaev-Zel'dovich Effect in a complete sample of low redshift (z<0.1) clusters. We present our first H₀ results from a subsample of clusters using new CBI observations and published X-ray data from ROSAT and ASCA.

Title:		The CMB Power Spectrum from CBI Mosaics
Authors:		Sievers, J. L.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.; Udomprasert, P. S.; Cartwright, J. K.; Mason, B. S.; Padin, S.; Myers, S. T.; Bond, J. R.; Contaldi, C.; Prunet, S.; Pogosyan, D.
Affiliation:		AA(Caltech), AB(Caltech), AC(Caltech), AD(Caltech), AE(Caltech), AF(Caltech), AG(Caltech), AH(Caltech), AI(NRAO), AJ(CITA), AK(CITA), AL(CITA), AM(CITA)
Publication:		American Astronomical Society, 199th AAS Meeting, #34.02; Bulletin of the American Astronomical Society, Vol. 33, p.1357
Publication Date:		12/2001
Origin:		AAS
Abstract Copyright:		(c) 2001: American Astronomical Society
Bibliographic Code:		2001AAS...199.3402S

Abstract

The Cosmic Background Imager is a thirteen element interferometer located in Chilean Andes designed to measure the angular power spectrum of the Cosmic Microwave Background. It uses low-noise HEMT receivers covering the frequency range of 26-36 GHz. We present the power spectrum to l=2000 measured by CBI from three 2x2 degree mosaics of 42 pointings each and discuss the implications of the results.

Title:		Measurements of the CMB Power Spectrum to L=4000 with the CBI
Authors:		Mason, B.; CBI Collaboration
Affiliation:		AA(Caltech)
Publication:		American Astronomical Society, 199th AAS Meeting, #34.01; Bulletin of the American Astronomical Society, Vol. 33, p.1357
Publication Date:		12/2001
Origin:		AAS
Abstract Copyright:		(c) 2001: American Astronomical Society
Bibliographic Code:		2001AAS...199.3401M

Abstract

We present a determination of the microwave background intrinsic anisotropy spectrum over the range L=500 to L=4000 derived from very deep observations of three pairs of fields with the Cosmic Background Imager (CBI). The CBI is a 13-element interferometer operating in the frequency range from 26 to 36 GHz at a site in the high Chilean Andes. Our results confirm earlier findings of a drop in the CMB power spectrum, and show that this continues to high L.

Title:		Polarization Observations with the Cosmic Background Imager
Authors:		Cartwright, J. K.; Padin, S.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.; Taylor, G. B.
Affiliation:		AA(California Institute of Technology), AB(California Institute of Technology), AC(California Institute of Technology), AD(California Institute of Technology), AE(California Institute of Technology), AF(National Radio Astronomy Observatory)
Publication:		American Astronomical Society, 198th AAS Meeting, #21.03; Bulletin of the American Astronomical Society, Vol. 33, p.816
Publication Date:		05/2001
Origin:		AAS
Abstract Copyright:		(c) 2001: American Astronomical Society
Bibliographic Code:		2001AAS...198.2103C

Abstract

We describe polarization observations of the CMBR with the Cosmic Background Imager, a 13 element interferometer which operates in the 26-36 GHz band from a site at 5000m in northern Chile. The array consists of 90-cm Cassegrain antennas mounted on a single, fully steerable platform; this platform can be rotated about the optical axis to facilitate polarization observations. The CBI employs single mode circularly polarized receivers, of which 12 are configured for LCP and one is configured for RCP. The 12 cross polarized baselines sample multipoles from l 600 to l 3500. The instrumental polarization of the CBI was calibrated with observations of 3C279, a bright polarized source which is unresolved by the CBI. Because the centimeter flux of 3C279 is variable, it was monitored twice per month for 8 months in 2000 with the VLA at 22 and 43 GHz. These observations also established the stability of the polarization characteristics of the CBI. This work was made possible by NSF grant AST-9802989

Title:		Determining H₀ with XMM-Newton and the Cosmic Background Imager
Authors:		Udomprasert, Patricia S.; Mason, Brian S.; Readhead, Anthony C. S.
Publication:		New Century of X-ray Astronomy, ASP Conference Proceedings Vol. 251. Edited by H. Inoue and H. Kunieda. ISBN: 1-58381-091-9. San Francisco: Astronomical Society of the Pacific, 2001., p.492
Publication Date:		00/2001
Origin:		ADS
Bibliographic Code:		2001ASPC..251..492U

Abstract

Not Available

Title:		First Results from the CBI
Authors:		Mason, B. S.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M.; Sievers, J.; Udomprasert, P.; Cartwright, J. K.; Padin, S.
Publication:		20th Texas Symposium on relativistic astrophysics, Austin, Texas, 10-15 Decem ber 2000, Melville, NY: American Institute of Physics, 2001, xix, 938 p. AIP conference proceedings, Vol. 586. Edited by J. Craig Wheeler and Hugo Martel. ISBN 0735400261, p.178 (AIPC Homepage)
Publication Date:		00/2001
Origin:		ADS
Bibliographic Code:		2001AIPC..586..178M

Abstract

Not Available

Title:		Observations of the Cosmic Microwave Background with the Cosmic Background Imager
Authors:		Sievers, J.; Mason, B.; Padin, S.; Pearson, T.; Readhead, A.; Shepherd, M.; Udomprasert, P.; Cartwright, J.
Affiliation:		AA(Caltech), AB(Caltech), AC(Caltech), AD(Caltech), AE(Caltech), AF(Caltech), AG(Caltech), AH(Caltech)
Publication:		American Astronomical Society, 197th AAS Meeting, #136.03; Bulletin of the American Astronomical Society, Vol. 33, p.724
Publication Date:		12/2000
Origin:		AAS
Abstract Copyright:		(c) 2000: American Astronomical Society
Bibliographic Code:		2000AAS...19713603S

Abstract

We present results on the intrinsic anisotropy CMB spectrum from the Cosmic Background Imager (CBI). The CBI is a 13 element interferometer located at 5,000 meters in northern Chile that covers the multipole range l ~ 600-3000. The low system noise (< ~ 30 K) and wide bandwidth (10 GHz from 26-36 GHz) allow the CBI to reach the cosmic variance limit in a 45' field at our lowest l range in less than a night.

Title:		Observations of the Sunyaev-Zel'dovich Effect with the Cosmic Background Imager
Authors:		Udomprasert, P. S.; Mason, B. S.; Readhead, A. C. S.
Affiliation:		AA(Caltech), AB(Caltech), AC(Caltech)
Publication:		American Astronomical Society, 197th AAS Meeting, #104.01; Bulletin of the American Astronomical Society, Vol. 32, p.1576
Publication Date:		12/2000
Origin:		AAS
Abstract Copyright:		(c) 2000: American Astronomical Society
Bibliographic Code:		2000AAS...19710401U

Abstract

We are engaged in a program with the Cosmic Background Imager (CBI), a 13-element interferometer recently installed at 5000 m in the Chilean Andes, to measure H₀ with 10% accuracy through observations of the Sunyaev-Zel'dovich effect (SZE) in a sample of low-redshift clusters (z<0.1). Our focus on nearby objects allows us to study a well-defined, orientation unbiased sample, minimizing systematic errors due to cluster elongation. The large angular extent of our targets will also provide us with a better understanding of the effects of non-smooth and non-isothermal cluster gas on the H₀ derivation. We present early results from our sample. We gratefully acknowledge support from NSF award AST-9802989, and PSU acknowledges support from an NSF Graduate Student Fellowship.

Title:		Polarization Observations with the Cosmic Background Imager
Authors:		Cartwright, J. K.; Padin, S.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.; Taylor, G. B.
Affiliation:		AA(California Institute of Technology), AB(California Institute of Technology), AC(California Institute of Technology), AD(California Institute of Technology), AE(California Institute of Technology), AF(National Radio Astronomy Observatory)
Publication:		American Astronomical Society, 197th AAS Meeting, #55.02; Bulletin of the American Astronomical Society, Vol. 32, p.1496
Publication Date:		12/2000
Origin:		AAS
Abstract Copyright:		(c) 2000: American Astronomical Society
Bibliographic Code:		2000AAS...197.5502C

Abstract

The linear polarization of the Cosmic Microwave Background Radiation is a fundamental prediction of the standard model. We report a limit on the polarization of the CMBR for l ~660. This limit was obtained with the Cosmic Background Imager, a 13 element interferometer which operates in the 26-36 GHz band from a site at 5000m in northern Chile. The array consists of 90-cm Cassegrain antennas mounted on a single, fully steerable platform; this platform can be rotated about the optical axis to facilitate polarization observations. The CBI employs single mode circularly polarized receivers, of which 12 are configured for LCP and one is configured for RCP. The 12 cross polarized baselines sample multipoles from l ~600 to l ~3500. The instrumental polarization of the CBI was calibrated with observations of 3C279, a bright polarized source which is unresolved by the CBI. Because the centimeter flux of 3C279 is variable, it was monitored twice per month for 8 months in '00 with the VLA at 22 and 43 GHz. These observations also established the stability of the polarization characteristics of the CBI. This work was made possible by NSF grant AST-9802989

Title:		Cbi
Authors:		Myers, Steven
Affiliation:		NRAO
Publication:		Presented at the KITP Miniprogram: Probing the Universe with the Cosmic Microwave Background, Jul 10, 2000, Kavli Institute for Theoretical Physics, University of California, Santa Barbara
Publication Date:		07/2000
Origin:		KITP
Bibliographic Code:		2000pucm.progE..32M

Abstract

Not Available

Title:		Mosaicing Techniques for CMBR Interferometry
Authors:		Myers, S. T.
Affiliation:		AA(NRAO, Socorro, NM, USA)
Publication:		New Cosmological Data and the Values of the Fundamental Parameters, International Astronomical Union. Symposium no. 201. Manchester, England, August 2000, meeting abstract.
Publication Date:		00/2000
Origin:		AUTHOR
Bibliographic Code:		2000IAUS..201E..82M

Abstract

There are several ongoing programs to build and use specially designed microwave interferometers to measure anisotropy in the Cosmic Microwave Background Radiation (CMBR) on angular scales of a degree and finer. Nominally, the maximum angular scale to which an array is sensitive is given by the primary beam defined by the field-of-view of a single antenna -- 45' at 31 GHz in the case of the Cosmic Background Imager (CBI) array built at Caltech and now operating at the Llano de Chajnantor site in Northern Chile. However, it is well-known that by combining a raster of fields with offset pointing, a technique known as ``mosaicing'', angular scales larger than a single primary beam can be probed. In the case of the CMBR, it is not just the desire of measuring larger scale fluctuations with a given instrument that drives the use of mosiacing. The size of the individual antenna elements also defines the intrinsic resolution of the interferometer in uv or Fourier space, which is related to the multipole l = 2π sqrt;{u²+v^s} that characterizes the power spectrum of the anisotropy fluctuations. The acoustic features in the CMBR power-spectrum are expected to have widths Deltal ~ 200, while the smallest baselines of the CBI measure Deltal ~ 600, and thus mosaicing will be necessary to resolve the acoustic peaks. In this paper the special problems and techniques for uv mosaicing of CMBR interferometer data are discussed, with particular application to the CBI for CMBR anisotropy power spectrum and Sunyaev-Zeldovich effect measurements.

Title:		The Sunyaev-Zeldovich Effect Imaging and Interferometry: BIMA-CBI-OVRO State of the Art and Future Prospects
Authors:		Myers, S. T.
Affiliation:		AA(NRAO, Socorro, NM, USA)
Publication:		New Cosmological Data and the Values of the Fundamental Parameters, International Astronomical Union. Symposium no. 201. Manchester, England, August 2000, meeting abstract.
Publication Date:		00/2000
Origin:		AUTHOR
Bibliographic Code:		2000IAUS..201E..19M

Abstract

This talk presents a summary of the most recent results from microwave and millimeter-wave surveys of the Sunyaev-Zeldovich Effect (SZE) in massive clusters of galaxies. The SZE is caused by Compton scattering of low-energy CMB photons off high-temperature ionized gas in cluster atmospheres, and is a direct measurement of the baryon content of the intercluster medium. New results from the Chicago-BIMA SZE survey of Carlstrom et al., the Penn-OVRO SZE program of Mason et al., and the Caltech-CBI SZE project of Padin et al. will be discussed, along with prospects for future imaging and interferometric studies of clusters to pin down the astrophysical properties of cluster baryons and dark matter as well as possible constraints on cosmological parameters.

Title:		The Cosmic Background Imager
Authors:		Pearson, T. J.; Readhead, A. C. S.; Padin, S.; Cartwright, J. K.; Mason, B. S.; Myers, S. T.; Shepherd, M. C.; Sievers, J. L.; Udomprasert, P. S.
Affiliation:		AA(California Institute of Technology)
Publication:		New Cosmological Data and the Values of the Fundamental Parameters, International Astronomical Union. Symposium no. 201. Manchester, England, August 2000, meeting abstract.
Publication Date:		00/2000
Origin:		AUTHOR
Bibliographic Code:		2000IAUS..201E...2P

Abstract

The Cosmic Background Imager (CBI) is an instrument designed to make images of the cosmic microwave background radiation and to measure its statistical properties on angular scales from 5 arc minutes to one degree (spherical harmonic scales from l ~ 3000 down to l ~ 300). The CBI is a 13-element interferometer mounted on a 6 meter platform operating in ten 1-GHz frequency bands from 26 GHz to 36 GHz. The instantaneous field of view of the instrument is 44 arcmin and its resolution ranges from 4.5 to 10 arcmin; larger fields can be imaged by mosaicing. At this frequency and resolution, the primary foreground is due to discrete extragalactic sources, which are monitored at the Owens Valley Radio Observatory and subtracted from the CBI visibility measurements. The instrument has been making observations since late 1999 of both primordial CMB fluctuations and the Sunyaev-Zeldovich effect in clusters of galaxies from its site at an altitude of 5000 meters near San Pedro de Atacama, in northern Chile. Observations will continue until mid-2001 or later. We will present images and power-spectrum estimates from the first few months of observations.

Title:		The Sunyaev-Zel'dovich Effect with the Cosmic Background Imager
Authors:		Udomprasert, P. S.; Mason, B. S.; Readhead, A. C. S.
Affiliation:		AA(Caltech, Pasadena CA, USA), AB(Caltech, Pasadena CA, USA), AC(Caltech, Pasadena CA, USA)
Publication:		Constructing the Universe with Clusters of Galaxies, IAP 2000 meeting, Paris, France, July 2000, Florence Durret & Daniel Gerbal Eds., available on CD-Rom and at http://www.iap.fr/Conferences/Colloque/coll2000/ contributions Reference: 4.4.6.
Publication Date:		00/2000
Origin:		AUTHOR
Bibliographic Code:		2000cucg.confE..48U

Abstract

We are engaged in a program with the Cosmic Background Imager (CBI), a 13-element interferometer recently installed at 5000 m in the Chilean Andes, to measure H₀ with 10 % accuracy through observations of the Sunyaev-Zel'dovich effect in a sample of nearby clusters. We discuss the capabilities of this new instrument and present our cluster sample and selection criteria, along with results from detailed simulations. We also present preliminary observations of Abell 478.

Title:		Measurements of the SZE in a Complete Sample of Nearby Clusters of Galaxies
Authors:		Myers, S. T.; Mason, B. S.
Affiliation:		AA(University of Pennsylvania), AB(University of Pennsylvania)
Publication:		American Astronomical Society, 194th AAS Meeting, #58.04; Bulletin of the American Astronomical Society, Vol. 31, p.916
Publication Date:		05/1999
Origin:		AAS
Abstract Copyright:		(c) 1999: American Astronomical Society
Bibliographic Code:		1999AAS...194.5804M

Abstract

Matter density and gravitational potential fluctuations in the Early and Late Universe imprint characteristic signatures on the Cosmic Microwave Background that can in principle be decoded through high-precision radio wavelength observations. Recent results from programs that put this into practice will be presented. The focus of the talk will be the Penn-OVRO Sunyaev-Zeldovich Survey, which targets a complete X-ray selected sample of nearby massive clusters of galaxies and has yielded a robust measurement of the baryonic mass in the intercluster medium, as well as a determination of the Hubble Constant. The future of these programs in the context of the Cosmic Background Imager project will also be discussed.

Title:		High Presision SZE Observations of Nearby Clusters: Prospects for the Pole
Authors:		Myers, S. T.
Affiliation:		AA(University of Pennsylvania)
Publication:		American Astronomical Society, 192nd AAS Meeting, #48.12; Bulletin of the American Astronomical Society, Vol. 30, p.1152
Publication Date:		09/1998
Origin:		AAS
Abstract Copyright:		(c) 1998: American Astronomical Society
Bibliographic Code:		1998AAS...192.4812M

Abstract

A survey to measure the Sunyaev-Zeldovich Effect (SZE) in a complete X-ray flux-limited sample of nearby clusters of galaxies is nearing completion using the OVRO 5.5m radiotelescope. These measurements have been limited by the atmospheric conditions in the Owens Valley, exacerbated by the problems introduced by beam-switching with a single-dish. An expanded sample of luminous nearby clusters will be surveyed using the Cosmic Background Imager, a compact CMB interferometer slated for installation in the Atacama desert of Chile in early 1999. The prospects for conducting these sorts of precision microwave observations from the Antarctic will be discussed, in comparison with existing OVRO data and future Atacama measurements. In particular, the pros and cons of a South Polar program will be examined carefully, particularly given the costs and logistical difficulties associated with Antarctic operations.

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