4 papers · 1 filter
Cosmological long-wavelength solutions in non-adiabatic multi-fluid systems
Hayami Iizuka, Tomohiro Harada
We develop a formulation of nonlinear cosmological perturbations on superhorizon scales in multi-fluid systems. It is based on the Arnowitt-Deser-Misner formalism combined with a s…
Singularity resolution and regular black hole formation in gravitational collapse in asymptotically safe gravity
Tomohiro Harada, Chiang-Mei Chen, Rituparna Mandal
We adopt an effective action inspired by asymptotically safe gravity, in which the effective gravitational constant is parametrized as …
Spin of Primordial Black Holes from Broad Power Spectrum: Radiation Dominated Universe
Indra Kumar Banerjee, Tomohiro Harada
We perform a study to obtain the initial spin or the nondimensional Kerr parameter of primordial black holes (PBHs) created during the radiation dominated phase of the univ…
Primordial black holes: formation, spin and type II
Tomohiro Harada
Primordial black holes (PBHs) may have formed through the gravitational collapse of cosmological perturbations that were generated and stretched during the inflationary era, later…