376 research outputs found
Lensing reconstruction from a patchwork of polarization maps
The lensing signals involved in CMB polarization maps have already been
measured with ground-based experiments such as SPTpol and POLARBEAR, and would
become important as a probe of cosmological and astrophysical issues in the
near future. Sizes of polarization maps from ground-based experiments are,
however, limited by contamination of long wavelength modes of observational
noise. To further extract the lensing signals, we explore feasibility of
measuring lensing signals from a collection of small sky maps each of which is
observed separately by a ground-based large telescope, i.e., lensing
reconstruction from a patchwork map of large sky coverage organized from small
sky patches. We show that, although the B-mode power spectrum obtained from the
patchwork map is biased due to baseline uncertainty, bias on the lensing
potential would be negligible if the B-mode on scales larger than the blowup
scale of noise is removed in the lensing reconstruction. As examples of
cosmological applications, we also show 1) the cross-correlations between the
reconstructed lensing potential and full-sky temperature/polarization maps from
satellite missions such as PLANCK and LiteBIRD, and 2) the use of the
reconstructed potential for delensing B-mode polarization of LiteBIRD
observation.Comment: 22 pages, 11 figures, replaced to match the published version in JCA
Reconstruction of the primordial fluctuation spectrum from the five-year WMAP data by the cosmic inversion method with band-power decorrelation analysis
The primordial curvature fluctuation spectrum is reconstructed by the cosmic
inversion method using the five-year WMAP data of the cosmic microwave
background temperature anisotropy. We apply the covariance matrix analysis and
decompose the reconstructed spectrum into statistically independent
band-powers. The statistically significant deviation from a simple power-law
spectrum suggested by the analysis of the first-year data is not found in the
five-year data except possibly at one point near the border of the wavenumber
domain where accurate reconstruction is possible.Comment: 9page
Fukanbi shisan shijo no kenkyu
制度:新 ; 文部省報告番号:乙1993号 ; 学位の種類:博士(経済学) ; 授与年月日:2005/11/15 ; 早大学位記番号:新411
Beating the Standard Quantum Limit with Four Entangled Photons
Precision measurements are important across all fields of science. In
particular, optical phase measurements can be used to measure distance,
position, displacement, acceleration and optical path length. Quantum
entanglement enables higher precision than would otherwise be possible. We
demonstrate an optical phase measurement with an entangled four photon
interference visibility greater than the threshold to beat the standard quantum
limit--the limit attainable without entanglement. These results open the way
for new high-precision measurement applications.Comment: 5 pages, 4 figures Author name was slightly modifie
Mapping dust column density in dark clouds by using NIR scattered light : Case of the Lupus 3 dark cloud
We present a method of mapping dust column density in dark clouds by using
near-infrared scattered light. Our observations of the Lupus 3 dark cloud
indicate that there is a well defined relation between (1) the H-Ks color of an
individual star behind the cloud, i.e., dust column density, and (2) the
surface brightness of scattered light toward the star in each of the J, H, and
Ks bands. In the relation, the surface brightnesses increase at low H-Ks
colors, then saturate and decrease with increasing H-Ks. Using a simple
one-dimensional radiation transfer model, we derive empirical equations which
plausibly represent the observed relationship between the surface brightness
and the dust column density. By using the empirical equations, we estimate dust
column density of the cloud for any directions toward which even no background
stars are seen. We obtain a dust column density map with a pixel scale of 2.3 x
2.3 arcsec^2 and a large dynamic range up to Av = 50 mag. Compared to the
previous studies by Juvela et al., this study is the first to use color excess
of the background stars for calibration of the empirical relationship and to
apply the empirical relationship beyond the point where surface brightness
starts to decrease with increasing column density
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