9 papers
Pebbles to Gems: Intermediate-mass black holes in the first star clusters
Benedetta Mestichelli, Manuel Arca Sedda, Marta Volonteri +9
The rapid assembly of supermassive black holes (SMBHs) observed at requires efficient seeding mechanisms in the early Universe. Population III (Pop. III) star clusters…
The Origin of Spin-Alignment of Dark Matter Subhalos
Daiki Osafune, Keiichi Wada, Tomoaki Ishiyama +1
Subhalo spin is essential for modeling galaxy formation and controlling systematic uncertainties in intrinsic alignment (IA) studies. However, the physical mechanisms governing sub…
Rapid emergence of overmassive black holes in the early Universe
Sunmyon Chon, Shingo Hirano, Tomoaki Ishiyama +2
The origin of supermassive black holes (SMBHs) remains a long-standing problem in astrophysics. Recent JWST observations reveal an unexpectedly abundant population of overmassive b…
A Semi-analytic Framework of Population III and Subsequent Galaxy Formation on Cosmological N-body Simulations
Tomoaki Ishiyama, Shingo Hirano
We develop a new semi-analytic framework of Population (Pop) III and subsequent galaxy formation designed to run on dark matter halo merger trees. In our framework, we consider the…
Comparison of simulations and semi-analytical model for WDM subhalo mass functions
Mizuki Ono, Takashi Okamoto, Shin'ichiro Ando +1
The Cold Dark Matter (CDM) model successfully explains large-scale structure formation, but challenges remain at smaller scales, leading to interest in Warm Dark Matter (WDM) as an…
Evolution of clustering in cosmological models with time-varying dark energy
Tomoaki Ishiyama, Francisco Prada, Anatoly A. Klypin
Observations favor cosmological models with a time-varying dark energy component. But how does dynamical dark energy (DDE) influence the growth of structure in an expanding Univers…