2002 Press Release
High Resolution CMB Power Spectrum from the Complete ACBAR Data Set.
Reichardt, C. L.; Ade P. A. R.; Bock, J. J.; Bond, J. R.; Brevik, J. A.; Contaldi, C. R.;
Daub, M. D.; Dempsey, J. T.; Goldstein, J. H.; Holzapfel, W. L.; Kuo, C. L.; Lange, A. E.; Lueker, M.;
Newcomb, M.; Peterson, J. B.; Ruhl, J.; Runyan, M. C.; Staniszewski, Z.
Astrophysical Journal 694 (2009) 1200-1219
In this paper, we present results from the complete set of cosmic microwave background (CMB) radiation
temperature anisotropy observations made with the Arcminute Cosmology
Bolometer Array Receiver (ACBAR) operating at 150 GHz. We include new data from the final 2005
observing season, expanding the number of detector-hours by 210% and the sky coverage by 490%
over that used for the previous ACBAR release.
As a result, the band-power uncertainties have been reduced by more than a factor of two on angular
scales encompassing the third to fifth acoustic peaks as well as the damping tail of the CMB
The calibration uncertainty has been reduced from 6% to 2.2% in temperature through a direct
comparison of the CMB anisotropy measured by ACBAR with that of the dipole-calibrated WMAP3 experiment.
The measured power spectrum is consistent with a spatially flat, ΛCDM cosmological model.
We see evidence for weak gravitational lensing of the CMB at >3-sigma significance
by comparing the likelihood for the best-fit lensed/unlensed models to the ACBAR+WMAP3 data.
On fine angular scales, there is weak evidence (1.7 sigma) for excess power above the level expected from
The source of this power cannot be constrained by the ACBAR 150 GHz observations alone; however,
if it is the same signal seen at 30 GHz by the CBI and BIMA experiments, then it has a spectrum consistent with the Sunyaev-Zel'dovich effect.
Also available at astro-ph/0801.1491.
Improved Measurements of the CMB Power Spectrum with ACBAR
Kuo, C. L.; Ade P. A. R.; Bock, J. J.; Bond, J. R.; Contaldi, C. R.;
Daub, M. D.; Goldstein, J. H.; Holzapfel, W. L.; Lange, A. E.; Lueker, M.;
Newcomb, M.; Peterson, J. B.; Reichardt, C.; Ruhl, J.; Runyan, M. C.; Staniszewski, Z.
The Astrophysical Journal, Volume 664, Issue 2, pp. 687-701
We report improved measurements of temperature anisotropies in the
cosmic microwave background (CMB) made with the Arcminute Cosmology
Bolometer Array Receiver (ACBAR). In this paper, we use a
new analysis technique and include 30% more data from the 2001 and 2002
observing seasons than the first release (Kuo et al. 2004) to derive
a new set of band-power measurements with significantly
The planet-based calibration used previously has been replaced by
comparing the flux of RCW38 as measured by ACBAR and BOOMERANG to transfer
the WMAP-based BOOMERANG calibration to ACBAR.
The resulting power spectrum is consistent with the
theoretical predictions for a spatially flat, dark energy dominated
Despite the exponential damping on small angular scales,
the primary CMB fluctuations are detected with a signal-to-noise ratio of
greater than 4 up to multipoles of l=2000.
This increase in the precision of the fine-scale CMB power spectrum
leads to only a modest decrease in the uncertainties on the parameters
of the standard cosmological model.
A joint analysis of the ACBAR results at 150 GHz and the CBI results at 30 GHz
in the multipole range 2000 < l < 3000 shows that the measured power
is consistent with the Sunyaev-Zel'dovich effect,
but disfavors interpretations in which the excess power seen with CBI has
a thermal spectrum.
The results reported here are derived from a subset of the
total ACBAR data set;
the final ACBAR power spectrum at 150 GHz will include 3.7 times more
effective integration time and 6.5 times more sky coverage than is used here.
Also available at astro-ph/0611198.
Millimeter Wavelength Brightness Fluctuations of the Atmosphere above the South Pole
Bussmann, R. S.; Holzapfel, W. L.; Kuo, C. L.
The Astrophysical Journal, Volume 622, Issue 2, pp. 1343-1355.
We report measurements of the millimeter wavelength brightness fluctuations produced by the atmosphere above the South Pole made with the Arcminute Cosmology Bolometer Array Receiver (ACBAR). The data span the 2002 austral winter during which ACBAR was mounted on the Viper Telescope at the South Pole. We recover the atmospheric signal in the presence of instrument noise by calculating the correlation between signals from distinct elements of the ACBAR bolometer array. With this method, it is possible to measure atmospheric brightness fluctuations with a high signal-to-noise ratio even under the most stable atmospheric conditions. The observed atmospheric signal is characterized by the parameters of the Kolmogorov-Taylor (KT) model, which are the amplitude and power-law exponent describing the atmospheric power spectrum and the two components of the wind angular velocity at the time of the observation. The KT model is typically a good description of the observed fluctuations, and fits to the data produce values of the Kolmogorov exponent that are consistent with theoretical expectations. By combining the wind angular velocity results with measurements of the wind linear velocity, we find that the altitude of the observed atmospheric fluctuations is consistent with the distribution of water vapor determined from radiosonde data. For data corresponding to frequency passbands centered on 150, 219, and 274 GHz, we obtain median fluctuation power amplitudes of (10, 38, 74) mK2 rad-5/3 in Rayleigh-Jeans temperature units. Comparing with previous work, we find that these median amplitudes are approximately an order of magnitude smaller than those found at the South Pole during the austral summer and at least 30 times lower than found at the ALMA site in the Atacama desert.
Also available at astro-ph/0412031.
First results from the arcminute cosmology bolometer array receiver
Runyan, M. C.; Ade, P. A. R.; Bock, J. J.; Bond, J. R.; Cantalupo, C.; Contaldi, C. R.;
Daub, M. D.; Goldstein, J. H.; Gomez, P. L.; Holzapfel, W. L.; Kuo, C. L.; Lange, A. E.;
Lueker, M.; Newcomb, M.; Peterson, J. B.; Pogosyan, D.; Romer, A. K.; Ruhl, J.; Torbet, E.; Woolsey, D.
New Astronomy Reviews, Volume 47, Issue 11-12, p. 915-923.
We review the first science results from the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a multi-frequency millimeter-wave receiver optimized for observations of the Cosmic Microwave Background (CMB) and the Sunyaev-Zel'dovich (SZ) effect in clusters of galaxies. ACBAR was installed on the 2 m Viper telescope at the South Pole in January 2001 and the results presented here incorporate data through July 2002. We present the power spectrum of the CMB at 150 GHz over the range l=150-3000 measured by ACBAR as well as estimates for the values of the cosmological parameters within the context of LambdaCDM models. We find that the inclusion of OmegaLambda greatly improves the fit to the power spectrum. We also observe a slight excess of small-scale anisotropy at 150 GHz; if interpreted as power from the SZ effect of unresolved clusters, the measured signal is consistent with CBI and BIMA within the context of the SZ power spectrum models tested.
Also available at astro-ph/0305553.
High Resolution Observations of the CMB Power Spectrum with
C.L. Kuo, P.A.R. Ade, J.J. Bock, C. Cantalupo, M.D. Daub, J.
Goldstein, W.L. Holzapfel , A.E. Lange, M. Lueker, M. Newcomb,
J.B. Peterson, J. Ruhl, M.C. Runyan, E. Torbet
The Astrophysical Journal, Volume 600, Issue 1, pp. 32-51.
We report the first measurements of anisotropy in the cosmic
microwave background (CMB) radiation with the Arcminute
Cosmology Bolometer Array Receiver ACBAR. The instrument was
installed on the 2.1m Viper telescope at the South Pole in
January 2001; the data presented here are the product of
observations up to and including July 2002. The two deep fields
presented here, have had offsets removed by subtracting lead and
trail observations and cover approximately 24 deg^2 of sky
selected for low dust contrast. These results represent the
highest signal to noise observations of CMB anisotropy to date;
in the deepest 150 GHz band map, we reached an RMS of 8.0 uK per
5' beam. The 3 degree extent of the maps, and small beamsize of
the experiment allow the measurement of the CMB anisotropy power
spectrum over the range $\ell = 150-3000$ with resolution of
$\Delta \ell=150$. The contributions of galactic dust and radio
sources to the observed anisotropy are negligible and are
removed in the analysis. The resulting power spectrum is found
to be consistent with the primary anisotropy expected in a
concordance $\Lambda$CDM Universe.
Also available at astro-ph/0212289.
Estimates of Cosmological Parameters Using the CMB Angular
Power Spectrum of ACBAR
J. H. Goldstein, P. A. R. Ade, J. J. Bock, J. R. Bond, C.
Cantalupo, C. R. Contaldi, M. D. Daub, W. L. Holzapfel, C. Kuo,
A. E. Lange, M. Lueker, M. Newcomb, J. B. Peterson, D.
Pogosyan, J. E. Ruhl, M. C. Runyan, E. Torbet
The Astrophysical Journal, Volume 599, Issue 2, pp. 773-785.
We report an investigation of cosmological parameters based on
the measurements of anisotropy in the cosmic microwave
background radiation (CMB) made by ACBAR. We use the ACBAR data
in concert with other recent CMB measurements to derive Bayesian
estimates of parameters in inflation-motivated adiabatic cold
dark matter models. We apply a series of additional cosmological
constraints on the shape and amplitude of the density power
spectrum, the Hubble parameter and from supernovae to further
refine our parameter estimates. Previous estimates of parameters
are confirmed, with sensitive measurements of the power spectrum
now ranging from \ell \sim 3 to 2800. Comparing individual best
model fits, we find that the addition of \Omega_\Lambda as a
parameter dramatically improves the fits. We also use the
high-\ell data of ACBAR, along with similar data from CBI and
BIMA, to investigate potential secondary anisotropies from the
Sunyaev-Zeldovich effect. We show that the results from the
three experiments are consistent under this interpretation, and
use the data, combined and individually, to estimate \sigma_8
from the Sunyaev-Zeldovich component.
Also availible at: astro-ph/0212517
The Arcminute Cosmology Bolometer Array Receiver
M.C. Runyan, P.A.R. Ade, R.S. Bhatia, J.J. Bock, M.D. Daub,
J.H. Goldstein, C.V. Haynes, W.L. Holzapfel, C.L. Kuo, A.E. Lange,
J. Leong, M. Lueker, M. Newcomb, J.B. Peterson, J. Ruhl, G. Sirbi,
E. Torbet, C. Tucker, A.D. Turner, D. Woolsey
The Astrophysical Journal Supplement Series, Volume 149, Issue 2, pp. 265-287.
We describe the Arcminute Cosmology Bolometer Array Receiver
(ACBAR); a multifrequency millimeter-wave receiver designed for
observations of the Cosmic Microwave Background (CMB) and the
Sunyaev-Zel'dovich effect in clusters of galaxies. The ACBAR
focal plane consists of a 16-pixel, background-limited, 240 mK
bolometer array that can be configured to observe simultaneously
at 150, 220, 280, and 350 GHz. With 4-5' FWHM Gaussian beam sizes
and a 3 degree azimuth chop, ACBAR is sensitive to a wide range
of angular scales. ACBAR was installed on the 2 m Viper telescope
at the South Pole in January 2001. We describe the design of the
instrument and its performance during the 2001 and 2002 observing
Also availible at: astro-ph/0303515