A5025957651- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Mesoporous Materials and Catalysis
- Astronomical Observations and Instrumentation
- Silicone and Siloxane Chemistry
- Chemical Synthesis and Analysis
- Polyoxometalates: Synthesis and Applications
- Pulsars and Gravitational Waves Research
- CCD and CMOS Imaging Sensors
- Image Processing Techniques and Applications
- Spectroscopy and Laser Applications
- Advanced Optical Sensing Technologies
- Molecular Spectroscopy and Structure
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Chemical Synthesis and Reactions
- Astro and Planetary Science
- Superconducting and THz Device Technology
- Thin-Film Transistor Technologies
Toyo University
2015-2024
Netherlands Institute for Radio Astronomy
2002-2024
Joint Institute for VLBI ERIC
2022-2024
National Astronomical Observatory of Japan
2007-2023
The Graduate University for Advanced Studies, SOKENDAI
1998-2023
Sojo University
2023
University College Cork
2023
Hitachi (Japan)
1979-2017
Waseda University
2006-2012
Kitasato Institute Hospital
2005-2007
We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual is 0.489 ± 0.017 mas (2.04 0.07 kpc), where error dominated by a systematic atmospheric contribution. This distance consistent with photometric distances from previous determined CH3OH maser astrometry presented in related paper. also find that source driving outflow, "TW-object," moves three-dimensional velocity >7 km s-1...
We report on results from new high-sensitivity, high-resolution 86GHz (3.5 millimeter) observations of the jet base in nearby radio galaxy M87, obtained by Very Long Baseline Array conjunction with Green Bank Telescope. The resulting image has a dynamic range exceeding 1500 to 1, highest ever achieved for this at frequency, resolving and imaging detailed formation/collimation structure down ~10 Schwarzschild radii (Rs). clearly confirms some important features known lower frequencies, i.e.,...
We investigated the detailed inner jet structure of M87 using Very Long Baseline Array data at 2, 5, 8.4, 15, 23.8, 43, and 86 GHz, especially focusing on multi-frequency properties radio core base. First, we measured a size region transverse to axis, defined as $W_{\rm c}$, each frequency \nu, found relation between c}$ $\nu$ c}(\nu) \propto \nu^{-0.71\pm0.05}$. Then, by combining c}(\nu)$ dependence position $r_{\rm c}(\nu)$, which was obtained our previous study, have constructed...
Abstract We study the kinematics of M87 jet using first-year data KVN and VERA Array (KaVA) large program, which has densely monitored at 22 43 GHz since 2016. find that apparent speeds generally increase from ≈0.3 c ≈0.5 mas base to ≈2.7 ≈20 mas, indicating is accelerated subluminal superluminal on these scales. perform a complementary kinematic analysis by archival Very Long Baseline monitoring observed in 2005–2009 1.7 moving relativistic up ≈5.8 distances 200–410 mas. combine two results...
Novel oligomeric alkoxysilanes consisting of double-four-ring (D4R) units functionalized with mono-, di-, and trialkoxysilyl groups (designated as 1, 2, 3, respectively) were designed nanobuilding blocks for synthesizing silica-based nanomaterials. Hydrolysis polycondensation these oligomers performed under acidic conditions. The gelation occurred much faster than monomeric, dimeric, cubic octameric alkoxysilanes, which should depend on both molecular size siloxane structures. Structural...
We report the initial results of our high-cadence monitoring program on radio jet in active galaxy M87, obtained by KVN and VERA Array (KaVA) at 22 GHz. This is a pilot study that preceded larger KaVA-M87 program, which currently ongoing. The was mostly performed every two to three weeks from December 2013 June 2014, recording rate 1 Gbps, obtaining data for total 10 epochs. successfully sequence good quality maps revealed rich structure this <~1 mas 20 mas, corresponding physical scales...
We conducted Very Long Baseline Array (VLBA) observations of seven nearby narrow-line Seyfert 1 (NLS1) galaxies at 1.7 GHz (λ18 cm) with milliarcsecond resolution. This is the first systematic very long baseline interferometry study focusing on central parsec-scale regions radio-quiet NLS1s. Five were detected a brightness temperature ≳ 5 × 106 K and contain radio cores high temperatures >6 107 K, indicating nonthermal process driven by jet-producing engines as in radio-loud NLS1s other...
We present ALMA ~0.02"-resolution observations of the nucleus nearby (~14 Mpc) type-2 AGN NGC 1068 at HCN/HCO+/HNC J=3-2 lines, as well their 13C isotopologue and vibrationally excited to scrutinize morphological/dynamical/chemical/physical properties dense molecular gas in putative dusty torus around a mass-accreting supermassive black hole. confirm almost east-west-oriented emission both morphologically dynamically, which we regard coming from torus. Bright is compact (<3 pc),...
Abstract The Korean very-long-baseline interferometry (VLBI) network (KVN) and VLBI Exploration of Radio Astrometry (VERA) Array (KaVA) is the first international array dedicated to high-frequency (23–43 GHz bands) observations in East Asia. Here, we report imaging three bright active galactic nuclei (AGNs) known for their complex morphologies: 4C 39.25, 3C 273, M 87. This one initial results KaVA's early operation. Our KaVA images reveal extended outflows with substructures such as knots...
Sagittarius A* (Sgr A*), the Galactic Center supermassive black hole (SMBH), is one of best targets to resolve innermost region SMBH with very long baseline interferometry (VLBI). In this study, we have carried out observations toward Sgr at 1.349 cm (22.223 GHz) and 6.950 mm (43.135 East Asian VLBI Network, as a part multi-wavelength campaign Event Horizon Telescope (EHT) in 2017 April. To mitigate scattering effects, physically motivated kernel model from Psaltis et al. (2018) parameters...
We performed astrometric observations with the VLBA of WB89-437, an H2O maser source in Outer spiral arm Galaxy. measure annual parallax 0.167 +/- 0.006 mas, corresponding to a heliocentric distance 6.0 0.2 kpc or Galactocentric 13.4 kpc. This value for is considerably smaller than kinematic 8.6 confirms presence faint toward l = 135 degrees. also measured full space motion object and find large peculiar ~20 km/s Galactic center. explains error estimate. that WB89-437 has same rotation speed...
The detection of NH3 inversion lines up to the level is reported toward central regions nearby galaxies NGC 253, Maffei 2, and IC 342. observed are 406 K (for ) 848 transition) above ground state reveal a warm ( K) molecular component all studied. tentatively detected line evidence for an even warmer (>400 Toward 342 2 global beam averaged abundances , while abundance relative H2 around 10-7. temperatures similar values found Galactic region. C-shocks produced in cloud-cloud collisions can...
We report on the detailed radio status of M87 jet during Very-High-Energy (VHE) gamma-ray flaring event in April 2010, obtained from high-resolution, multi-frequency, phase-referencing VLBA observations. especially focus properties for base (the core) and peculiar knot HST-1, which are currently favored as emitting sites. During VHE event, HST-1 region remains stable terms its structure flux density optically thin regime above 2GHz, being consistent with no signs enhanced activities reported...
A 1280×960 floating diffusion storage global shutter image sensor is implemented in a 3D stacked back illuminated indirect time of flight (iToF). The sensor, achieves 18,000e- full well capacity and 32% quantum efficiency (QE) with pyramid surface for diffraction (PSD) structure [1], utilizing 3.5µm pixel. Low power consumption also achieved, due to low leakage current the iToF pixel resistance Cu-Cu connection metal wiring. These device architectures enable high resolution wide dynamic...
Unique low-dimensional SiO2-based nanomaterials can be encapsulated and synthesized inside the nanometer-scale one-dimensional internal spaces of carbon nanotubes (CNTs). In this study, various single-walled CNTs (SWNTs) double-walled (DWNTs) having different diameters are used as containers for cubic octameric H8Si8O12 molecules. High-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy observations revealed that, depending...
High resolution (0.4 arcsec) Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 observations of HCO+(4-3) and HCN(4-3) toward a mid-stage infrared bright merger VV114 have revealed compact nuclear (<200 pc) extended (3 - 4 kpc) dense gas distribution across the eastern part galaxy pair. We find significant enhancement emission in an unresolved broad (290km/s) component found nucleus VV114, we suggest associated with surrounding material around Active Galactic Nucleus (AGN), mass...
(abridged) Very long baseline interferometry (VLBI) observations at 86$\,$GHz (wavelength, $\lambda = 3\,$mm) reach a resolution of about 50 $\mu$as, probing the collimation and acceleration regions relativistic outflows in active galactic nuclei. To extend statistical studies compact extragalactic jets, large global 86 GHz VLBI survey 162 radio sources was conducted 2010-2011 using Global Millimeter Array. The data attained typical sensitivity 0.1 Jy image 5 mJy/beam, providing successful...
ABSTRACT We report the detection of two CH 3 OH lines ( J K = 2 –1 and –2 ) between progenitor’s disks (“Overlap”) mid-stage merging galaxy VV 114 obtained using Atacama Large Millimeter/submillimeter Array (ALMA) Band 4. The detected emission shows an extended filamentary structure (∼3 kpc) across with relatively large velocity width (FWZI ∼ 150 km s −1 ). is only significant in “overlap” not nuclei. Assuming optically thin local thermodynamic equilibrium, we found column density relative...
Abstract We have found an extragalactic water-vapor megamaser source in NGC 5793, edge-on spiral galaxy. Its spectral profile shows two distinct high-velocity maser features, one on each side of the systemic velocity They are almost symmetrically offset from velocity. The isotropic luminosity features is as large 125 L⊙ at a distance 50 Mpc. Weaker were possibly detected. constructed model which explains our observational data. HO emission emitted nearly circumnuclear disk, or torus, whose...