Kazuhiko Kojima

Generation of Curvature Perturbations with Extra Anisotropic Stress (2009)

Kojima, Kazuhiko, Kajino, Toshitaka, Mathews, Grant J.

We study the evolution of curvature perturbations and the cosmic microwave background (CMB) power spectrum in the presence of an hypothesized extra anisotropic stress in the early universe. Such...

Evolution of Cosmological Perturbations in the Presence of Primordial Magnetic Fields (2009)

Kojima, Kazuhiko, Ichiki, Kiyotomo

Possible existence of the primordial magnetic fields has affected the structure formation of the universe. In this paper it is shown that the initial conditions for density perturbations with...

Neutrino mass effects on vector and tensor CMB anisotropies in the presence of a primordial magnetic field (2008)

Kojima, Kazuhiko, Ichiki, Kiyotomo, Yamazaki, Dai G., Kajino, Toshitaka, Mathews, Grant J.

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 studies of the...