[Show abstract][Hide abstract] ABSTRACT: Atmosphere is one of the most important noise sources for ground-based Cosmic
Microwave Background (CMB) experiments. By increasing optical loading on the
detectors, it amplifies their effective noise, while its fluctuations introduce
spatial and temporal correlations between detected signals. We present a
physically motivated 3d-model of the atmosphere total intensity emission in the
millimeter and sub-millimeter wavelengths. We derive an analytical estimate for
the correlation between detectors time-ordered data as a function of the
instrument and survey design, as well as several atmospheric parameters such as
wind, relative humidity, temperature and turbulence characteristics. Using
numerical computation, we examine the effect of each physical parameter on the
correlations in the time series of a given experiment. We then use a
parametric-likelihood approach to validate the modeling and estimate atmosphere
parameters from the POLARBEAR-I project first season data set. We compare our
results to previous studies and weather station measurements, and find that the
polarization fraction of atmospheric emission is below 1.0 percent. The
proposed model can be used for realistic simulations of future ground-based CMB
[Show abstract][Hide abstract] ABSTRACT: Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial cosmic microwave background (CMB) and thereby induces new, small-scale B-mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even- and odd-parity E- and B-mode polarization mapped over ∼30 square degrees of the sky measured by the POLARBEAR experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B modes is found at 4.2σ (stat+sys) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda cold dark matter cosmological model. This measurement demonstrates a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B-mode signal in searches for primordial gravitational waves.
[Show abstract][Hide abstract] ABSTRACT: We reconstruct the gravitational lensing convergence signal from cosmic microwave background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with cosmic infrared background maps from the Herschel satellite. From the cross spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0σ and indication of the presence of a lensing B-mode signal at a significance of 2.3σ. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces POLARBEAR auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics.
[Show abstract][Hide abstract] ABSTRACT: We report a measurement of the B-mode polarization power spectrum in the
cosmic microwave background (CMB) using the POLARBEAR experiment in Chile. The
faint B-mode polarization signature carries information about the Universe's
entire history of gravitational structure formation, and the cosmic inflation
that may have occurred in the very early Universe. Our measurement covers the
angular multipole range 500 < l < 2100 and is based on observations of 30
square degrees with 3.5 arcmin resolution at 150 GHz. On these angular scales,
gravitational lensing of the CMB by intervening structure in the Universe is
expected to be the dominant source of B-mode polarization. Including both
systematic and statistical uncertainties, the hypothesis of no B-mode
polarization power from gravitational lensing is rejected at 97.5% confidence.
The band powers are consistent with the standard cosmological model. Fitting a
single lensing amplitude parameter A_BB to the measured band powers, A_BB =
1.12 +/- 0.61 (stat) +0.04/-0.10 (sys) +/- 0.07 (multi), where A_BB = 1 is the
fiducial WMAP-9 LCDM value. In this expression, "stat" refers to the
statistical uncertainty, "sys" to the systematic uncertainty associated with
possible biases from the instrument and astrophysical foregrounds, and "multi"
to the calibration uncertainties that have a multiplicative effect on the
measured amplitude A_BB.
[Show abstract][Hide abstract] ABSTRACT: Primary fluctuations in both temperature and polarization of the Cosmic
Microwave Background (CMB) reflect the properties of the Universe from the Big
Bang until the photons decoupled from matter 380,000 years later. These primary
fluctuations are then lensed by large-scale structures (such as clusters of
galaxies and filaments of dark matter), with the result that the distribution
and properties of dark matter, including the masses of neutrinos, can be
determined more accurately by extracting the lensing information than through
studying the primary fluctuations alone. Polarization lensing can give cleaner,
higher resolution results than temperature lensing. The correlation of lensed
CMB polarization with large-scale structure, traced through the Cosmic Infrared
Background, was recently detected; however, this correlation does not trace all
structure and depends on the relationship between the infrared flux from the
galaxies and the underlying mass distribution. Here we report the detection of
gravitational lensing directly from CMB polarization measurements. With these
data, we have made a census of essentially all structure integrated along the
line of sight through the full depth of the observable Universe on 30 square
degrees of the sky, and we find good agreement with expectations from the
standard Lambda cold-dark matter cosmology.
[Show abstract][Hide abstract] ABSTRACT: The Polarbear Cosmic Microwave Background (CMB) polarization experiment is
currently observing from the Atacama Desert in Northern Chile. It will
characterize the expected B-mode polarization due to gravitational lensing of
the CMB, and search for the possible B-mode signature of inflationary
gravitational waves. Its 250 mK focal plane detector array consists of 1,274
polarization-sensitive antenna-coupled bolometers, each with an associated
lithographed band-defining filter. Each detector's planar antenna structure is
coupled to the telescope's optical system through a contacting dielectric
lenslet, an architecture unique in current CMB experiments. We present the
initial characterization of this focal plane.
[Show abstract][Hide abstract] ABSTRACT: We present the design and characterization of the POLARBEAR experiment.
POLARBEAR will measure the polarization of the cosmic microwave background
(CMB) on angular scales ranging from the experiment's 3.5 arcminute beam size
to several degrees. The experiment utilizes a unique focal plane of 1,274
antenna-coupled, polarization sensitive TES bolometers cooled to 250
milliKelvin. Employing this focal plane along with stringent control over
systematic errors, POLARBEAR has the sensitivity to detect the expected small
scale B-mode signal due to gravitational lensing and search for the large scale
B-mode signal from inflationary gravitational waves.
POLARBEAR was assembled for an engineering run in the Inyo Mountains of
California in 2010 and was deployed in late 2011 to the Atacama Desert in
Chile. An overview of the instrument is presented along with characterization
results from observations in Chile.
[Show abstract][Hide abstract] ABSTRACT: Observations of the temperature anisotropy of the Cosmic Microwave Background
(CMB) lend support to an inflationary origin of the universe, yet no direct
evidence verifying inflation exists. Many current experiments are focussing on
the CMB's polarization anisotropy, specifically its curl component (called
"B-mode" polarization), which remains undetected. The inflationary paradigm
predicts the existence of a primordial gravitational wave background that
imprints a unique B-mode signature on the CMB's polarization at large angular
scales. The CMB B-mode signal also encodes gravitational lensing information at
smaller angular scales, bearing the imprint of cosmological large scale
structures (LSS) which in turn may elucidate the properties of cosmological
neutrinos. The quest for detection of these signals; each of which is orders of
magnitude smaller than the CMB temperature anisotropy signal, has motivated the
development of background-limited detectors with precise control of systematic
effects. The POLARBEAR experiment is designed to perform a deep search for the
signature of gravitational waves from inflation and to characterize lensing of
the CMB by LSS. POLARBEAR is a 3.5 meter ground-based telescope with 3.8
arcminute angular resolution at 150 GHz. At the heart of the POLARBEAR receiver
is an array featuring 1274 antenna-coupled superconducting transition edge
sensor (TES) bolometers cooled to 0.25 Kelvin. POLARBEAR is designed to reach a
tensor-to-scalar ratio of 0.025 after two years of observation -- more than an
order of magnitude improvement over the current best results, which would test
physics at energies near the GUT scale. POLARBEAR had an engineering run in the
Inyo Mountains of Eastern California in 2010 and will begin observations in the
Atacama Desert in Chile in 2011.
[Show abstract][Hide abstract] ABSTRACT: We describe the Cosmic Microwave Background (CMB) polarization experiment
called Polarbear. This experiment will use the dedicated Huan Tran Telescope
equipped with a powerful 1,200-bolometer array receiver to map the CMB
polarization with unprecedented accuracy. We summarize the experiment, its
goals, and current status.
[Show abstract][Hide abstract] ABSTRACT: POLARBEAR is a Cosmic Microwave Background (CMB) polarization experiment that will search for evidence of inflationary gravitational waves and gravitational lensing in the polarization of the CMB. This proceeding presents an overview of the design of the instrument and the architecture of the focal plane, and shows some of the recent tests of detector performance and early data from the ongoing engineering run.