A5082106553- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Radio Astronomy Observations and Technology
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
- Particle physics theoretical and experimental studies
- Muscle activation and electromyography studies
- Molecular Spectroscopy and Structure
- Motor Control and Adaptation
- Advanced Thermodynamics and Statistical Mechanics
- Black Holes and Theoretical Physics
- Mechanical and Optical Resonators
- Solar and Space Plasma Dynamics
- Scientific Measurement and Uncertainty Evaluation
- Astronomical Observations and Instrumentation
The University of Tokyo
2016-2025
Kavli Institute for the Physics and Mathematics of the Universe
2016-2025
Institute for Advanced Study
2018-2025
Tokyo Institute of Technology
2024
Panasonic (Poland)
2024
Panasonic (Japan)
2022
Tohoku University
2022
Keio University
1997-2021
Tokyo University of Science
2010-2021
Waseda University
2020-2021
We simulate the growth of galaxies and their central supermassive black holes by implementing a suite semi-analytic models on output Millennium Run, very large simulation concordance Λ cold dark matter cosmogony. Our procedures follow detailed assembly history each object are able to track evolution all more massive than Small Magellanic Cloud throughout volume comparable that modern redshift surveys. In this first paper we supplement previous treatments activity with new model for 'radio'...
We combine data from a number of N-body simulations to predict the abundance dark haloes in cold matter (CDM) universes over more than four orders magnitude mass. A comparison different suggests that dominant uncertainty our results is systematic and smaller 10–30 per cent at all masses, depending on halo definition used. In particular, 'Hubble volume' τCDM ΛCDM cosmologies allow massive clusters be predicted with uncertainties well below those expected currently planned observational...
(Abridged) The violent hierarchical nature of the LCDM cosmology poses serious difficulties for formation disk galaxies. To help resolve these issues, we describe a new, merger-driven scenario cosmological galaxies at high redshifts that supplements standard model based on dissipational collapse.In this picture, large gaseous disks may be produced from high-angular momentum mergers systems are gas-dominated, i.e. M_gas/(M_gas +M_star > 0.5 height merger. Pressurization multiphase...
(abridged) We use large cosmological simulations to study the origin of primordial star-forming clouds in a Lambda CDM universe, by following formation dark matter halos and cooling gas within them. To model physics chemically pristine gas, we employ non-equilibrium treatment chemistry 9 species include molecular hydrogen. explore hierarchical growth bound structures forming at redshifts z = 25 - 30 with total masses range 10^5 10^6 Msun. The complex interplay between gravitational...
We perform a large set of radiation hydrodynamics simulations primordial star formation in fully cosmological context. Our statistical sample 100 First Stars show that the first generation stars have wide mass distribution M_popIII = 10 ~ 1000 M_sun. run to generate star-forming gas clouds. then follow protostar each cloud and subsequent protostellar evolution until accretion onto is halted by stellar radiative feedback. The rates differ significantly among clouds which largely determine...
We study the formation of first generation stars in standard cold dark matter model. use a very high resolution cosmological hydrodynamic simulation that achieves dynamic range ~1010 length scale. With accurate treatment atomic and molecular physics, including effect line opacities cooling by collision-induced continuum emission, it allows us to chemothermal evolution primordial gas clouds densities up ρ ~ 2 × 10-8 g cm-3 (nH 1016 cm-3) without assuming any priori equation state, an...
We discuss the formation of supermassive black holes in early universe, and how to probe their subsequent evolution with upcoming mm/sub‐mm telescope ALMA. first focus on chemical radiative conditions for hole formation, particular considering radiation trapping molecular dissociation effects. then turn our attention towards magnetic properties halos where form, show that presence turbulence may lead a dynamo, which could support process by providing an efficient means transporting angular...
The first stars fundamentally transformed the early universe by emitting light and producing heavy elements. These effects were predetermined mass distribution of stars, which is thought to have been fixed a complex interplay gas accretion protostellar radiation. We performed radiation-hydrodynamics simulations that followed growth primordial protostar through stages as star with thermonuclear burning. circumstellar disk was evaporated ultraviolet radiation from when its 43 times Sun. Such...
The nature of the first generation stars in universe remains largely unknown. Observations imply existence massive primordial early history universe, and standard theory for growth cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation formation follows relevant atomic molecular processes a gas expanding universe. results show primeval density fluctuations left over from Big Bang can drive tiny...
We review our current understanding of how the first galaxies formed at end cosmic dark ages, a few 100 million years after Big Bang. Modern large telescopes discovered redshifts greater than seven, whereas theoretical studies have just reached degree sophistication necessary to make meaningful predictions. A crucial ingredient is feedback exerted by generation stars, through UV radiation, supernova blast waves, and chemical enrichment. The key goal derive signature be observed with upcoming...
We investigate the formation of first stars at end cosmic dark ages with a suite three-dimensional, moving-mesh simulations that directly resolve collapse gas beyond protostar centre matter minihalo. The cover more than 25 orders magnitude in density and have maximum spatial resolution 0.05 R⊙, which extends well below radius individual protostars captures their interaction surrounding gas. In analogy to previous studies employed sink particles, we find Keplerian disc around primary...
Supermassive stars (SMSs) forming via very rapid mass accretion (Mdot >~ 0.1 Msun/yr) could be precursors of supermassive black holes observed beyond redshift about 6. Extending our previous work, we here study the evolution primordial growing under such until stellar reaches 10^{4 - 5} Msun. Our calculations show that a star becomes while passing through "supergiant protostar" stage, whereby has bloated envelope and contracting inner core. The radius increases monotonically with mass, =~...
We perform a large set of cosmological simulations early structure formation and follow the evolution 1540 star-forming gas clouds to derive mass distribution primordial stars. The star in our is characterized by two distinct populations, so-called Population III.1 stars formed under influence far ultraviolet (FUV) radiation (Population III.2D stars). In this work, we determine stellar masses using dependences on physical properties cloud and/or external photodissociating intensity from...
We measure the redshift-space correlation function from a spectroscopic sample of 2783 emission line galaxies FastSound survey. The survey, which uses Subaru Telescope and covers redshift ranges $1.19<z<1.55$, is first cosmological study at such high redshifts. detect clear anisotropy due to distortions (RSD) both in as separations parallel perpendicular sight its quadrupole moment. RSD has been extensively used test general relativity on scales $z<1$. Adopting LCDM cosmology with fixed...
The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding role this process. We report Atacama Large Millimeter/submillimeter Array detection an oxygen emission line at a wavelength 88 micrometers from galaxy epoch about 700 million years after Big Bang. abundance is estimated one-tenth that Sun. nondetection far-infrared continuum indicates deficiency dust galaxy. A carbon 158 also not detected,...
ABSTRACT We present coupled stellar evolution (SE) and 3D radiation-hydrodynamic (RHD) simulations of the primordial protostars, their immediate environment, dynamic accretion history under influence ionizing dissociating UV feedback. Our SE RHD calculations result in a wide diversity final masses covering 10 <?CDATA ${M}_{\odot }$?> ≲ M * 3 . The formation very massive (≳250 ) stars is possible weak feedback, whereas ordinary (a few ×10 form when feedback can efficiently halt accretion....
Abstract We present the number densities and physical properties of bright galaxies spectroscopically confirmed at z ∼ 7–14. Our sample is composed 60 spec 7–14, including recently = 12.34–14.18 with JWST, as well new confirmations 6.583–7.643 −24 < M UV −21 mag using ALMA Keck. JWST/NIRSpec observations have also revealed that very galaxy candidates 10–13 identified from ground-based telescope images before JWST are passive 3–4, emphasizing necessity strict screening spectroscopy in...
The discovery of luminous quasars at redshift z ~ 6 indicates the presence supermassive black holes (SMBHs) mass ~10^9 Msun when Universe was less than one billion years old. This finding presents several challenges for theoretical models. Here, we present first multi-scale simulations that, together with a self-regulated model SMBH growth, produce quasar 6.5 in LCDM paradigm. We follow hierarchical assembly history most massive halo 3 Gpc^3 volume, and find that this 8x 10^{12} forming...
We use gigaparticle N-body simulations to study galaxy cluster populations in Hubble volumes of ΛCDM (Ωm = 0.3, ΩΛ 0.7) and τCDM 1) world models. Mapping past light cones locations the computational space, we create mock sky surveys dark matter structure z ≃ 1.4 over 10,000 deg2 0.5 two full spheres. Calibrating Jenkins mass function at 0 with samples ~1.5 million clusters, show that fit describes survey counts ≲20% accuracy all redshifts for systems more massive than poor groups (5 × 1013...
We analyse the properties of substructures within dark matter haloes (subhaloes) using a set high-resolution numerical simulations formation structure in ΛCDM universe. Our simulation includes 11 massive clusters as well region mean density, allowing us to study spatial and mass distribution down resolution limit 109h−1 M⊙. also investigate how vary function 'parent' halo which they are located. find that substructure depends at most weakly on parent is described by power law. The radial...
We study the formation of dark halos in a ΛCDM universe under assumption that cold matter (CDM) particles have finite cross section for elastic collisions. compare evolution when CDM mean free paths are comparable to halo sizes with collisionless and fluid limits. show few collisions per particle Hubble time at center can substantially affect central density profile. Cross sections an order magnitude larger produce sufficient relaxation rich clusters develop core radii range 100-200 h-1 kpc....