11 papers
Determining Kerr black hole spin and inclination from a segment of the critical curve in black hole images
Kenta Hioki, Umpei Miyamoto, Tomohiro Harada
We present a method for determining the spin parameter and inclination angle of a non-extremal Kerr black hole from segments of the critical curve identified in black hol…
COSMOS: A numerical relativity code specialized for PBH formation
Chul-Moon Yoo, Hirotada Okawa, Albert Escrivà +7
Primordial black holes (PBHs) are black holes generated in the early universe without having gone through stellar evolution. In the standard formation process, PBHs are formed from…
Supermassive black hole seeds from direct collapse of CDM-curvature peaks
Marco Galoppo, Marco Bruni, Tomohiro Harada
We study black hole (BH) formation from the nonlinear growth and collapse of primordial perturbations during the matter-dominated era. Modelling cold dark matter (CDM) as pressurel…
Gravitational wave emission from nonspherical collapse in an early matter-dominated era using N-body simulations
Albert EscrivÃ, Tomohiro Harada, Kazunori Kohri +2
We study the dynamics of the collapse of a nonspherical overdense patch during an early matter-dominated era and the associated production of gravitational waves (GWs) using a semi…
Cosmological discrete self-similarity in primordial black hole formation
Luis E. Padilla, Tomohiro Harada, Ethan Milligan +1
We demonstrate that discrete self-similarity (DSS), originally discovered in the collapse of a massless scalar field in an asymptotically flat system, survives in primordial black…
Numerical simulation of type II primordial black hole formation
Koichiro Uehara, Albert EscrivÃ, Tomohiro Harada +2
This study investigates the formation of type II primordial black holes (PBHs) resulting from extremely large amplitudes of initial fluctuations in a radiation-dominated universe.…