ORCID Profile
0000-0003-3070-9240
Current Organisation
University of Tokyo
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Publisher: SPIE
Date: 16-12-2020
DOI: 10.1117/12.2561841
Publisher: American Physical Society (APS)
Date: 26-01-2021
Publisher: Springer Science and Business Media LLC
Date: 05-09-2022
Publisher: American Physical Society (APS)
Date: 04-2020
Publisher: SPIE
Date: 15-12-2020
DOI: 10.1117/12.2562243
Publisher: Springer Science and Business Media LLC
Date: 27-01-2020
DOI: 10.1007/S10909-019-02329-W
Abstract: 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 in idual 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.
Publisher: EDP Sciences
Date: 05-2021
DOI: 10.1051/0004-6361/202039975
Abstract: We measured the cross-correlation between galaxy weak lensing data from the Kilo Degree Survey (KiDS-1000, DR4) and cosmic microwave background (CMB) lensing data from the Atacama Cosmology Telescope (ACT, DR4) and the Planck Legacy survey. We used two s les of source galaxies, selected with photometric redshifts, (0.1 z B 1.2) and (1.2 z B 2), which produce a combined detection significance of the CMB lensing and weak galaxy lensing cross-spectrum of 7.7 σ . With the lower redshift galaxy s le, for which the cross-correlation was detected at a significance of 5.3 σ , we present joint cosmological constraints on the matter density parameter, Ω m , and the matter fluctuation litude parameter, σ 8 , marginalising over three nuisance parameters that model our uncertainty in the redshift and shear calibration as well as the intrinsic alignment of galaxies. We find our measurement to be consistent with the best-fitting flat ΛCDM cosmological models from both Planck and KiDS-1000. We demonstrate the capacity of CMB weak lensing cross-correlations to set constraints on either the redshift or shear calibration by analysing a previously unused high-redshift KiDS galaxy s le (1.2 z B 2), with the cross-correlation detected at a significance of 7 σ . This analysis provides an independent assessment for the accuracy of redshift measurements in a regime that is challenging to calibrate directly owing to known incompleteness in spectroscopic surveys.
Publisher: American Astronomical Society
Date: 04-09-2019
Publisher: SPIE
Date: 21-12-2020
DOI: 10.1117/12.2563050
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Toshiya Namikawa.