Search Results for author: Toshiya Namikawa

Found 16 papers, 5 papers with code

Constraining reionization with the first measurement of the cross-correlation between the CMB optical-depth fluctuations and the Compton y-map

no code implementations1 Feb 2021 Toshiya Namikawa, Anirban Roy, Blake D. Sherwin, Nicholas Battaglia, David N. Spergel

Since the power spectrum of the electron density fluctuations is constrained by the $\delta\tau$ auto spectrum, the temperature constraints should be only weakly model-dependent on the details of the electron distributions and should be statistically representative of the temperature in ionized bubbles during reionization.

PICO Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies

Delensing the CMB with the cosmic infrared background: the impact of foregrounds

no code implementations1 Feb 2021 Antón Baleato Lizancos, Anthony Challinor, Blake D. Sherwin, Toshiya Namikawa

We also show, by means of an analytic model, that the bias arising from the higher-point functions of the CIB itself ought to be negligible.

Cosmology and Nongalactic Astrophysics

Analyzing clustering of astrophysical gravitational-wave sources: Luminosity-distance space distortions

no code implementations8 Jul 2020 Toshiya Namikawa

We present a formulation of observed number density fluctuations of gravitational-wave (GW) sources in a three dimensional space.

Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology

CMB lensing bi-spectrum: assessing analytical predictions against full-sky lensing simulations

no code implementations27 Dec 2018 Toshiya Namikawa, Benjamin Bose, François R. Bouchet, Ryuichi Takahashi, Atsushi Taruya

Following on an earlier paper, we test analytical predictions of the CMB lensing bi-spectrum against full-sky lensing simulations, and discuss their validity and limitation in detail.

Cosmology and Nongalactic Astrophysics

Constraints on Patchy Reionization from Planck CMB Temperature Trispectrum

1 code implementation31 Oct 2017 Toshiya Namikawa

We present constraints on the patchy reionization by measuring the trispectrum of the Planck 2015 cosmic microwave background (CMB) temperature anisotropies.

Cosmology and Nongalactic Astrophysics

Geometry and growth contributions to cosmic shear observables

no code implementations16 Jun 2017 José Manuel Zorrilla Matilla, Zoltán Haiman, Andrea Petri, Toshiya Namikawa

We explore the sensitivity of weak lensing observables to the expansion history of the universe and to the growth of cosmic structures, as well as the relative contribution of both effects to constraining cosmological parameters.

Cosmology and Nongalactic Astrophysics

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

2 code implementations5 Jun 2017 Ryuichi Takahashi, Takashi Hamana, Masato Shirasaki, Toshiya Namikawa, Takahiro Nishimichi, Ken Osato, Kosei Shiroyama

The data sets include full-sky convergence and shear maps from redshifts $z=0. 05$ to $5. 3$ at intervals of $150 \, h^{-1}{\rm Mpc}$ comoving radial distance (corresponding to a redshift interval of $\Delta z \simeq 0. 05$ at the nearby universe), enabling the construction of a mock shear catalog for an arbitrary source distribution up to $z=5. 3$.

Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology

CMB internal delensing with general optimal estimator for higher-order correlations

no code implementations1 Mar 2017 Toshiya Namikawa

We present a new method for delensing $B$ modes of the cosmic microwave background (CMB) using a lensing potential reconstructed from the same realization of the CMB polarization (CMB internal delensing).

Cosmology and Nongalactic Astrophysics

Testing parity-violating physics from cosmic rotation power reconstruction

no code implementations23 Dec 2016 Toshiya Namikawa

We study the reconstruction of the cosmic rotation power spectrum produced by parity-violating physics, with an eye to ongoing and near future cosmic microwave background (CMB) experiments such as BICEP Array, CMBS4, LiteBIRD and Simons Observatory.

Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology High Energy Physics - Theory

Lensing reconstruction from a patchwork of polarization maps

1 code implementation26 May 2014 Toshiya Namikawa, Ryo Nagata

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.

Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics

Bias-Hardened CMB Lensing with Polarization

no code implementations9 Oct 2013 Toshiya Namikawa, Ryuichi Takahashi

The contamination from beam asymmetry and polarization angle uncertainties, however, can generate mean-field biases for the EB estimator.

Cosmology and Nongalactic Astrophysics

Bias-Hardened CMB Lensing

no code implementations1 Sep 2012 Toshiya Namikawa, Duncan Hanson, Ryuichi Takahashi

We present new methods for lensing reconstruction from CMB temperature fluctuations which have smaller mean-field and reconstruction noise bias corrections than current lensing estimators, with minimal loss of signal-to-noise.

Cosmology and Nongalactic Astrophysics

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