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 $G(ε) = G_{N} /[1 + \tildeÏ (G_{N}^{2} ε)^…
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…
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…