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Magnetic field spectrum at cosmological recombination revisited
Shohei Saga, Kiyotomo Ichiki, Keitaro Takahashi +1
If vector type perturbations are present in the primordial plasma before recombination, the generation of magnetic fields is known to be inevitable through the Harrison mechanism.…
Primordial magnetic fields from self-ordering scalar fields
Kouichirou Horiguchi, Kiyotomo Ichiki, Toyokazu Sekiguchi +1
A symmetry-breaking phase transition in the early universe could have led to the formation of cosmic defects. Because these defects dynamically excite not only scalar and tensor ty…
Impact of anisotropic stress of free-streaming particles on gravitational waves induced by cosmological density perturbations
Shohei Saga, Kiyotomo Ichiki, Naoshi Sugiyama
Gravitational waves (GWs) are inevitably induced at second-order in cosmological perturbations through non-linear couplings with first order scalar perturbations, whose existence i…