199 citations · 1.7k across the 46 of their papers we have counts for
21 papers · 1 filter
Primordial Curvature Fluctuation and Its Non-Gaussianity in Models with Modulated Reheating
Kazuhide Ichikawa, Teruaki Suyama, Tomo Takahashi +1
We investigate non-Gaussianity in the modulated reheating scenario where fluctuations of the decay rate of the inflaton generate adiabatic perturbations, paying particular attentio…
Probing the Effective Number of Neutrino Species with Cosmic Microwave Background
Kazuhide Ichikawa, Toyokazu Sekiguchi, Tomo Takahashi
We discuss how much we can probe the effective number of neutrino species N_nu with cosmic microwave background alone. Using the data of WMAP, ACBAR, CBI and BOOMERANG experiments,…
Non-Gaussianity, Spectral Index and Tensor Modes in Mixed Inflaton and Curvaton Models
Kazuhide Ichikawa, Teruaki Suyama, Tomo Takahashi +1
We study non-Gaussianity, the spectral index of primordial scalar fluctuations and tensor modes in models where fluctuations from the inflaton and the curvaton can both contribute…
Primordial Helium Abundance from CMB: a constraint from recent observations and a forecast
Kazuhide Ichikawa, Toyokazu Sekiguchi, Tomo Takahashi
We studied a constraint on the primordial helium abundance Y_p from current and future observations of CMB. Using the currently available data from WMAP, ACBAR, CBI and BOOMERANG,…
Neutrino mass constraint from CMB and its degeneracy with other cosmological parameters
Kazuhide Ichikawa
We show that the cosmic microwave background (CMB) data of WMAP can give subelectronvolt limit on the neutrino mass: m_nu < 0.63 eV (95% CL). We also investigate its degeneracy wit…
The Hubble constant and dark energy from cosmological distance measures
Kazuhide Ichikawa, Tomo Takahashi
We study how the determination of the Hubble constant from cosmological distance measures is affected by models of dark energy and vice versa. For this purpose, constraints on the…