759 citations · 864 across the 10 of their papers we have counts for
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Neutrino mass effects on vector and tensor CMB anisotropies in the presence of a primordial magnetic field
Kazuhiko Kojima, Kiyotomo Ichiki, Dai G. Yamazaki +2
If a primordial magnetic field (PMF) is present during photon decoupling and afterward, a finite neutrino mass can affect all modes of the CMB. In this work, we expand on earlier s…
Cosmological Signatures of the Interaction between Dark-Energy and Massive Neutrinos
Kiyotomo Ichiki, Yong-Yeon Keum
We investigate whether interaction between massive neutrinos and quintessence scalar field is the origin of the late time accelerated expansion of the universe. We present cosmolog…
Cosmic Shear from Scalar-Induced Gravitational Waves
Devdeep Sarkar, Paolo Serra, Asantha Cooray +2
Weak gravitational lensing by foreground density perturbations generates a gradient mode in the shear of background images. In contrast, cosmological tensor perturbations induce a…
Cosmic microwave background constraints on a decaying cosmological term related to the thermal evolution
Riou Nakamura, Masa-aki Hashimoto, Kiyotomo Ichiki
We constrain the thermal evolution of the universe with a decaying cosmological term by using the method of the analysis for the Wilkinson Microwave Anisotropy Probe (WMAP) observa…
Electromagnetic Properties of the Early Universe
Keitaro Takahashi, Kiyotomo Ichiki, Naoshi Sugiyama
Detailed physical processes of magnetic field generation from density fluctuations in the pre-recombination era are studied. Solving Maxwell equations and the generalized Ohm's law…
Constraints on Generalized Dark Energy from Recent Observations
Kiyotomo Ichiki, Tomo Takahashi
Effects of a generalized dark energy fluid is investigated on cosmic density fluctuations such as cosmic microwave background. As a general dark energy fluid, we take into consider…