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.
LiteBIRD is a cosmic microwave background polarization experiment with the goal of measuring the tensor-to-scalar ratio with a total uncertainty of
δ
r
<
0.001
. It will survey the full sky from ...space for 3 years in 15 frequency bands spanning 34–448 GHz. We are developing detector arrays for the six lowest frequency bands covering 34–99 GHz. The arrays are populated with lenslet-coupled sinuous antennas, triplexer bandpass filters, and transition-edge sensor (TES) bolometers. We have measured the electrical and thermal properties of several TES designs to determine space-optimized parameters. The design balances requirements for low saturation power of the space environment while maintaining a fast time response for use with a continuously rotating half-wave plate. We have achieved detector saturation powers below 1 pW, with time constants faster than 1 ms, at a 100 mK bath temperature measured using both time- and frequency-division multiplexed SQUID readout systems. Using this information, we have fabricated multi-chroic pixels with antenna-coupled space-optimized bolometers.
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.
The Simons Array (SA) is a cosmic microwave background (CMB) polarization experiment comprised of three telescopes that will observe the CMB at 90, 150, 220, and 270 GHz with more than 22,000 ...Transition Edge Sensor (TES) bolometers. The cryogenic receivers inside each telescope are named POLARBEAR-2a, POLARBEAR-2b, and POLARBEAR-2c (PB-2a, PB-2b, and PB-2c, respectively). To allow for the large number of detectors, SA uses frequency-division multiplexing with multiplexing factor of 40. We describe the process developed to assemble the readout circuit repeatably for SA. After assembly, we characterize the readout circuit and TESs at cryogenic temperatures in a condition of negligible incident optical power. Impedances in the readout circuit bias our estimates of TES parameters, and we describe a method to account for this.
The POLARBEAR-2 Experiment Suzuki, A.; Ade, P.; Akiba, Y. ...
Journal of low temperature physics,
09/2014, Letnik:
176, Številka:
5-6
Journal Article
Recenzirano
Odprti dostop
We present an overview of the design and development of the POLARBEAR-2 experiment. The POLARBEAR-2 experiment is a cosmic microwave background polarimetry experiment, which aims to characterize the ...small angular scale B-mode signal due to gravitational lensing and search for the large angular scale B-mode signal from inflationary gravitational waves. The experiment will have a 365 mm diameter multi-chroic focal plane filled with 7,588 polarization sensitive antenna-coupled Transition Edge Sensor bolometers and will observe at 95 and 150 GHz. The focal plane is cooled to 250 mK. The bolometers will be read-out by SQUIDs with
32
×
frequency domain multiplexing. The experiment will utilize high purity alumina lenses and thermal filters to achieve the required high optical throughput. A continuously rotating, cooled half-wave plate will be used to give stringent control over systematic errors. The experiment is designed to achieve a noise equivalent temperature of 5.7
μ
K
s
, and this allows us to constrain the signal from the inflationary primordial gravitational corresponding to a tensor-to-scalar ratio of
r
=
0.01
(
2
σ
). POLARBEAR-2 will also be able to put a constraint on the sum of neutrino masses to 90 meV (
1
σ
) with POLARBEAR-2 data alone and 65 meV (
1
σ
) when combined with the Planck satellite. We plan to start observations in 2014 in the Atacama Desert in Chile.
The polarization of the cosmic microwave background (CMB) holds a wealth of information about fundamental physics and cosmology. The faint B-mode polarization pattern of the CMB is generated by ...gravitational lensing from large scale structure and possibly by primordial gravitational waves from inflation. Polarbear is an ongoing experiment on the Huan Tran Telescope to measure CMB polarization and the Simons Array is the successor experiment. The author analyzed data from Polarbear to recalibrate the polarization properties of the experiment after a continuously-rotating half-wave plate was added. The CMB data set was a deep search on a 500 deg2 patch of sky to constrain the B-mode signal at large angular scales. The half-wave plate was added to modulate the polarization signal in order to improve low-frequency sensitivity. The polarization angles and efficiencies of every detector in the array needed to be recalibrated and their impact on instrumental systematics estimated. Observations of a polarized supernova remnant were used to determine the polarization properties of the experiment. The author also made contributions during four months of field work acquiring the data published from the first two seasons of Polarbear observations. The Simons Array is an expansion of this experiment to three telescopes with upgraded receivers and an order of magnitude more sensitivity. In the lab, the author has characterized detectors for POLARBEAR-2A, the first upgraded receiver in the Simons Array. This receiver will have 1897 multichroic pixels sensitive to radiation in bands centered at 90 and 150 GHz. The detectors operate at the quantum limit using transition edge sensors coupled to dual-polarization sinuous antennas. They are read out with superconducting quantum interference devices using frequency-domain multiplexing. This thesis is a combination of data analysis for POLARBEAR and experimental lab work for POLARBEAR-2 and the Simons Array.
We present a measurement of the B-mode polarization power spectrum of the cosmic microwave background (CMB) using data taken from 2014 July to 2016 December with the Polarbear experiment. The CMB ...power spectra are measured using observations at 150 GHz with an instantaneous array sensitivity of on a 670 square degree patch of sky centered at (R.A., decl.) = (+0h12m0s, −59°18′). A continuously rotating half-wave plate is used to modulate polarization and to suppress low-frequency noise. We achieve 32 K arcmin effective polarization map noise with a knee in sensitivity of = 90, where the inflationary gravitational-wave signal is expected to peak. The measured B-mode power spectrum is consistent with a ΛCDM lensing and single dust component foreground model over a range of multipoles 50 ≤ ≤ 600. The data disfavor zero at 2.2 using this range of Polarbear data alone. We cross-correlate our data with Planck full mission 143, 217, and 353 GHz frequency maps and find the low- B-mode power in the combined data set to be consistent with thermal dust emission. We place an upper limit on the tensor-to-scalar ratio r < 0.90 at the 95% confidence level after marginalizing over foregrounds.
Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future ...satellite cosmic microwave background (CMB) polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXA’s H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the CMB by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34 and 448 GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxy’s foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5 K for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/
f
noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second Sun–Earth Lagrangian point, L2, are planned for 3 years. An international collaboration between Japan, the USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science, JAXA, selected LiteBIRD as the strategic large mission No. 2.
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