Yutaka Fujita
A5026147033- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Neutrino Physics Research
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Nuclear physics research studies
- Coastal and Marine Dynamics
- Refrigeration and Air Conditioning Technologies
- Cardiac Valve Diseases and Treatments
- Scientific Research and Discoveries
- Particle physics theoretical and experimental studies
- Turbomachinery Performance and Optimization
- Aquatic Ecosystems and Phytoplankton Dynamics
- Laser-Plasma Interactions and Diagnostics
- Action Observation and Synchronization
Tokyo Metropolitan University
1997-2025
Tokyo Institute of Technology
1984-2023
Niigata University Medical and Dental Hospital
2018-2022
Ehime University
2022
Saitama University
2022
University of Miyazaki
2022
Osaka University
2011-2020
Shimizu (Japan)
1991-2020
HUN-REN Institute for Nuclear Research
2019
Osaka Health Science University
2006-2018
We have studied the morphology–density relation and morphology–cluster-centric-radius using a volume-limited sample (0.05 < z 0.1, Mr* −20.5) of Sloan Digital Sky Survey (SDSS) data. Major improvements compared with previous work are: (i) automated galaxy morphology classification capable separating galaxies into four types; (ii) three-dimensional local density estimation; (iii) extension field region. found that in SDSS data for both our morphological classifiers, Cin Tauto, as fractions...
The X-Ray Imaging and Spectroscopy Mission (XRISM) is the successor to 2016 Hitomi mission that ended prematurely. Like Hitomi, primary science goals are examine astrophysical problems with precise highresolution X-ray spectroscopy. XRISM promises discover new horizons in astronomy. carries a 6 x pixelized micro-calorimeter on focal plane of an mirror assembly co-aligned CCD camera covers same energy band over large field view. utilizes heritage, but all designs were reviewed. attitude orbit...
Using a simple model of molecular cloud evolution, we have quantitatively estimated the change star formation rate (SFR) disk galaxy falling radially into potential well cluster galaxies. The SFR is affected by ram-pressure from intracluster medium (ICM). As approaches center, increases to twice initial value, at most, in with high gas density and deep well, or central pressure $\sim 10^{-2} cm^{-3} keV$ because compresses galaxy. However, this increase does not affect color significantly....
We consider several mechanisms that possibly affect the evolution of disk galaxies in clusters using analytical models based on a hierarchical clustering scenario. especially focus subclusters located around main cluster. show ram-pressure stripping cannot be always ignored subclusters, although their masses are much smaller than The star-formation rate galaxy may gradually decrease by warm gas (`strangulation') However, we find could start before strangulation is completed, if field...
We show that the anomaly of positron fraction observed by PAMELA experiment can be attributed to recent supernova explosion(s) in a dense gas cloud near Earth. Protons are accelerated around remnant. Electrons and positrons created through hadronic interactions inside cloud. Their spectrum is harder than background because remnant spends much time radiative phase. Our scenario predicts antiproton flux dominates for $\ensuremath{\gtrsim}100\text{ }\text{ }\mathrm{GeV}$. compare results with...
Abstract We present an analysis of a Suzaku observation the link region between galaxy clusters A 399 and 401. obtained metallicity intracluster medium (ICM) up to cluster virial radii for first time. determined where two cross each other ($\sim 2$ Mpc away from their centers) found that it is comparable in inner regions 0.2\: Z_\odot$). It unlikely uniformity due mixing caused by collision. Since ram-pressure too small strip interstellar galaxies around radius cluster, fairly high we there...
<i>Context. <i/>Measurements of intracluster gas temperatures out to large radii, where much the galaxy cluster mass resides, are important for using clusters precision cosmology and studies physics. Previous attempts measure robust at virial radii have failed.<i>Aims. <i/>The goal this work is temperature profile very relaxed symmetric Abell 2204 possibly reaching radius.<i>Methods. <i/>Taking advantage its low particle background due low-Earth orbit, <i>Suzaku<i/> data used outer 2204....
We present a weak-lensing analysis of X-ray galaxy groups and clusters selected from the XMM-XXL survey using first-year data Hyper Suprime-Cam (HSC) Subaru Strategic Program. Our joint focuses on 136 spectroscopically confirmed X-ray-selected systems at 0.031 < z 1.033 detected in 25sqdeg XXL-N region. characterize mass distributions individual establish concentration-mass (c-M) relation for XXL sample, by accounting selection bias statistical effects, marginalizing over remaining...
We present ALMA Band 6 observations of the CO(2-1), HCN(3-2), and HCO$^{+}$(3-2) lines in nearby radio galaxy / brightest cluster (BCG) NGC 1275 with spatial resolution $\sim20$ pc. In previous observations, CO(2-1) emission was detected as radial filaments lying east-west direction. resolved inner filament found that cannot be represented by a simple infalling stream both morphologically kinematically. The observed complex nature resembles cold gas structure predicted recent numerical...
Abstract We present an analysis of the first two XRISM/Resolve spectra well-known Seyfert-1.5 active galactic nucleus (AGN) in NGC 4151, obtained 2023 December. Our work focuses on nature narrow Fe K α emission line at 6.4 keV, strongest and most common X-ray observed AGN. The total is found to consist three components. Even narrowest component resolved with evident ,1 (6.404 keV) ,2 (6.391 contributions a 2:1 flux ratio, fully consistent neutral gas negligible bulk velocity. Subject...
We consider nonthermal emission from clusters of galaxies produced by particle acceleration resonant scattering Alfv\'{e}n waves driven fluid turbulence through the Lighthill mechanism in intracluster medium. assume that is cluster mergers. find can accelerate electrons up to \gamma ~10^5 scattering. also turbulent give enough energy produce observed diffuse radio relic if have a pool with ~10^3. This explain hard X-ray magnetic field small (~< \mu G) or spectrum flatter than Kolmogorov law....
A simple model is constructed to evaluate the change of star formation rate a disk galaxy due environmental effects in clusters galaxies. Three effects, (1) tidal force from potential well cluster, (2) increase external pressure when plows into intracluster medium, (3) high-speed encounters between galaxies, are investigated. General analysis indicates that increases significantly molecular clouds rises above $\sim 3\times 10^5 cm^{-3} K$ 10^8$ yr. The cluster pressures infalling towards...
We study cosmic-ray acceleration in a supernova remnant (SNR) and the escape from it. model nonthermal particle photon spectra for hidden SNR open cluster Westerlund 2, old-age mixed-morphology W 28. assume that shock propagates low-density cavity, which is created heated through activities of progenitor stars and/or previous explosions. indicate diffusion coefficient cosmic-rays around SNRs less than ~1% away them. compare our predictions with gamma-ray molecular clouds illuminated by...
We report the detection of a new feature at centre NGC 1275 in Perseus cluster, hosting radio source 3C 84. This emerges ~ 2 mas (~ 0.8 pc) north central core recent 15 and 43 GHz VLBA images, seems to be counterjet known jet expanding south core. Apparently, two jets were born through an outburst around 2005. From ratio apparent lengths from core, we found that angle line sight is θ=65^\circ\pm 16^\circ, which not much different outer generated by activity 1959 constrains theories on...
On the basis of high-resolution two-dimensional hydrodynamic simulations, we show that bulk gas motions in a cluster galaxies, which are naturally expected during process hierarchical structure formation universe, have serious impact on core. We found represented by acoustic-gravity waves create local but strong turbulence, reproduces complicated X-ray structures recently observed cores. Moreover, if wave amplitude is large enough, they can suppress radiative cooling Contrary to previous...
We report Suzaku observations of the northern half Hydra A cluster out to ~1.4 Mpc, reaching virial radius. This is first a medium-size (kT ~3 keV) Two were conducted, north-west and north-east offsets, which continue in filament direction void large-scale structure Universe, respectively. The X-ray emission distribution galaxies elongate direction. temperature profiles two directions are mostly consistent with each other within error bars drop 1.5 keV at r_500. As observed by hot clusters,...
We present results of four-pointing Suzaku X-ray observations (total ∼200 ks) the intracluster medium (ICM) in A1835 galaxy cluster (kT ∼ 8 keV, z = 0.253) out to virial radius (rvir 2.9 Mpc) and beyond. Faint emission from ICM rvir is detected. The temperature gradually decreases with ∼8 keV inner region ∼2 at rvir. entropy profile shown flatten beyond r500, disagreement r1.1 dependence predicted accretion shock heating model. thermal pressure range 0.3r500 ≲ r agrees well that obtained...
Magnetic field is ubiquitous in the Universe and it plays essential roles various astrophysical phenomena, yet its real origin evolution are poorly known. This article reviews current understanding of magnetic fields interstellar medium, Milky Way Galaxy, external galaxies, active galactic nuclei, clusters cosmic web. Particularly, review concentrates on achievements that have been provided by centimeter meter wavelength radio observations. The also introduces methods to analyze linear...
We explain the excess of antiproton fraction recently reported by AMS-02 experiment considering collisions between cosmic-ray protons accelerated a local supernova remnant and surrounding dense cloud. The same "|$pp$| collisions" provide right ratio daughter particles to fit observed positron simultaneously in natural model parameters. happened relatively lower metallicity than major sources. cutoff energy electrons marks age |${\sim }10^{5}$| years, while may extend higher energy. Both...
Active galaxies contain a supermassive black hole at their center that grows by accreting matter from the surrounding galaxy. The accretion process in about central 10 parsecs has not been directly resolved previous observations because of small apparent angular sizes involved. We observed active nucleus Circinus Galaxy using submillimeter interferometry. A dense inflow molecular gas was evident on subparsec scales. calculated less than 3% this is accreted hole, with rest being ejected...
Abstract The X-Ray Imaging and Spectroscopy Mission (XRISM) is a joint mission between the Japan Aerospace Exploration Agency (JAXA) National Aeronautics Space Administration (NASA) in collaboration with European (ESA). In addition to three space agencies, universities research institutes from Japan, North America, Europe have joined contribute developing satellite onboard instruments, data-processing software, scientific observation program. XRISM successor ASTRO-H (Hitomi) mission, which...
Abstract We present XRISM Resolve observations of the core hot, relaxed galaxy cluster Abell 2029 (A2029). find that line-of-sight bulk velocity intracluster medium (ICM) within central 180 kpc is at rest with respect to brightest galaxy, a 3 σ upper limit ∣ v < 100 km s −1 . robustly measure field-integrated ICM dispersion be = 169 ± 10 , obtaining similar results for both single-temperature and two-temperature plasma models account cool core. This result, if ascribed isotropic...