Fumie Tazaki
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View article: Spectral analysis of a parsec-scale jet in M 87: Observational constraint on the magnetic field strengths in the jet
Spectral analysis of a parsec-scale jet in M 87: Observational constraint on the magnetic field strengths in the jet Open
Context. Because of its proximity and the large size of its black hole, M 87 is one of the best targets for studying the launching mechanism of active galactic nucleus jets. Currently, magnetic fields are considered to be an essential fact…
View article: A ring-like accretion structure in M87 connecting its black hole and jet
A ring-like accretion structure in M87 connecting its black hole and jet Open
The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation 1,2 . Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted a…
View article: Precessing jet nozzle connecting to a spinning black hole in M87
Precessing jet nozzle connecting to a spinning black hole in M87 Open
Powerful relativistic jets in active galactic nuclei (AGN) are believed to be originated from the accretion of material onto the supermassive black hole (SMBH) 1 . The nearby radio galaxy M87 is one of the best examples of this phenomenon,…
View article: Spectral analysis of a parsec-scale jet in M87: Observational constraint on the magnetic field strengths in the jet
Spectral analysis of a parsec-scale jet in M87: Observational constraint on the magnetic field strengths in the jet Open
Because of its proximity and the large size of its black hole, M87 is one of the best targets for studying the launching mechanism of active galactic nucleus jets. Currently, magnetic fields are considered to be an essential factor in the …
View article: Super-Resolved Image of M87 Observed with East Asian VLBI Network
Super-Resolved Image of M87 Observed with East Asian VLBI Network Open
Obtaining high-resolution images at centimeter-or-longer wavelengths is vital for understanding the physics of jets. We reconstructed images from the M87 22 GHz data observed with the East Asian VLBI Network (EAVN) by using the regularized…
View article: Transverse Oscillations of the M87 Jet Revealed by KaVA Observations
Transverse Oscillations of the M87 Jet Revealed by KaVA Observations Open
Recent VLBI monitoring has found transverse motions of the M87 jet. However, due to the limited cadence of previous observations, details of the transverse motion have not been fully revealed yet. We have regularly monitored the M87 jet at…
View article: Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN)
Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN) Open
The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists o…
View article: Collimation of the Relativistic Jet in the Quasar 3C 273
Collimation of the Relativistic Jet in the Quasar 3C 273 Open
The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs) is one of the key questions to understand the nature of AGN jets. However, little is known …
View article: The Photon Ring in M87*
The Photon Ring in M87* Open
We report measurements of the gravitationally lensed secondary image—the first in an infinite series of so-called “photon rings”—around the supermassive black hole M87* via simultaneous modeling and imaging of the 2017 Event Horizon Telesc…
View article: The Intrinsic Structure of Sagittarius A* at 1.3 cm and 7 mm
The Intrinsic Structure of Sagittarius A* at 1.3 cm and 7 mm Open
Sagittarius A* (Sgr A*), the Galactic Center supermassive black hole (SMBH), is one of the best targets in which to resolve the innermost region of an SMBH with very long baseline interferometry (VLBI). In this study, we have carried out o…
View article: East Asian VLBI Network observations of active galactic nuclei jets: imaging with KaVA+Tianma+Nanshan
East Asian VLBI Network observations of active galactic nuclei jets: imaging with KaVA+Tianma+Nanshan Open
The East Asian Very Long Baseline Interferometry (VLBI) Network (EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China, Japan and Korea. EAVN aims at forming a joint VLBI Network by…
View article: Effect of Multicomponent Exercise and Nutrition Support on the Cognitive Function of Older Adults: A Randomized Controlled Trial
Effect of Multicomponent Exercise and Nutrition Support on the Cognitive Function of Older Adults: A Randomized Controlled Trial Open
Masakazu Imaoka,1–4 Hidetoshi Nakao,1,2 Misa Nakamura,1,2 Fumie Tazaki,1,2 Motohiro Maebuchi,5 Masahisa Ibuki,5 Masatoshi Takeda1,2 1Department of Rehabilitation, Osaka Kawasaki Rehabilitation University, Kaizuka, Osaka 597-0104, Japan; 2C…
View article: SMILI: Sparse Modeling Imaging Library for Interferometry
SMILI: Sparse Modeling Imaging Library for Interferometry Open
SMILI is an open-source python-interfaced library for interferometric imaging using sparse sampling techniques and other regularization methods. SMILI is mainly designed for very long baseline interferometry and has been under the active d…
View article: Jet kinematics of the quasar 4C+21.35 from observations with the KaVA very long baseline interferometry array
Jet kinematics of the quasar 4C+21.35 from observations with the KaVA very long baseline interferometry array Open
We present the jet kinematics of the flat spectrum radio quasar (FSRQ) 4C+21.35 using time-resolved KaVA very long baseline interferometry array radio maps obtained from 2014 September to 2016 July. During two out of three observing campai…
View article: Source-Frequency Phase-Referencing Observation of AGNs with KaVA Using Simultaneous Dual-Frequency Receiving
Source-Frequency Phase-Referencing Observation of AGNs with KaVA Using Simultaneous Dual-Frequency Receiving Open
The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implem…
View article: Source-Frequency Phase-Referencing Observation of AGNS with KAVA Using Simultaneous Dual-Frequency Receiving
Source-Frequency Phase-Referencing Observation of AGNS with KAVA Using Simultaneous Dual-Frequency Receiving Open
The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to implem…
View article: Parabolic Jets from the Spinning Black Hole in M87
Parabolic Jets from the Spinning Black Hole in M87 Open
The M87 jet is extensively examined by utilizing general relativistic magnetohydrodynamic (GRMHD) simulations, as well as the steady axisymmetric force-free electrodynamic (FFE) solution. Quasi-steady funnel jets are obtained in GRMHD simu…
View article: Imaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope Using Sparse Modeling
Imaging the Schwarzschild-radius-scale Structure of M87 with the Event Horizon Telescope Using Sparse Modeling Open
We propose a new imaging technique for radio and optical/infrared interferometry. The proposed technique reconstructs the image from the visibility amplitude and closure phase, which are standard data products of short-millimeter very long…
View article: Superresolution Full-polarimetric Imaging for Radio Interferometry with Sparse Modeling
Superresolution Full-polarimetric Imaging for Radio Interferometry with Sparse Modeling Open
We propose a new technique for radio interferometry to obtain superresolution full-polarization images in all four Stokes parameters using sparse modeling. The proposed technique reconstructs the image in each Stokes parameter from the cor…
View article: Super-resolution Full Polarimetric Imaging for Radio Interferometry with Sparse Modeling
Super-resolution Full Polarimetric Imaging for Radio Interferometry with Sparse Modeling Open
We propose a new technique for radio interferometry to obtain super-resolution full polarization images in all four Stokes parameters using sparse modeling. The proposed technique reconstructs the image in each Stokes parameter from the co…
View article: STUDY OF SWIFT/BAT SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI OBSERVED WITH SUZAKU
STUDY OF SWIFT/BAT SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI OBSERVED WITH SUZAKU Open
We systematically analyze the broadband (0.5–200 keV) X-ray spectra of hard X-ray (>10 keV) selected local low-luminosity active galactic nuclei (LLAGNs) observed with Suzaku and Swift /BAT. The sample consists of 10 LLAGNs detected with S…
View article: Millimeter VLBI observations of Sgr A* with KaVA and KVN
Millimeter VLBI observations of Sgr A* with KaVA and KVN Open
We present recent observation results of Sgr A* at millimeter obtained with VLBI arrays in Korea and Japan. 7 mm monitoring of Sgr A* is part of our AGN large project. The results at 7 epochs during 2013-2014, including high resolution map…
View article: A radio detection survey of narrow-line Seyfert 1 galaxies using very long baseline interferometry at 22 GHz
A radio detection survey of narrow-line Seyfert 1 galaxies using very long baseline interferometry at 22 GHz Open
We conducted a high-sensitivity radio detection survey for 40 narrow-line Seyfert 1 (NLS1) galaxies using a very long baseline interferometry (VLBI) technique at 22 GHz through phase-referencing long-time integration and using a newly deve…
View article: PRECL: A new method for interferometry imaging from closure phase
PRECL: A new method for interferometry imaging from closure phase Open
For short-wavelength VLBI observations, it is difficult to measure the phase of the visibility function accurately. The closure phases are reliable measurements under this situation, though it is not sufficient to retrieve all of the phase…
View article: Imaging black holes with sparse modeling
Imaging black holes with sparse modeling Open
We introduce a new imaging method for radio interferometry based on sparse- modeling. The direct observables in radio interferometry are visibilities, which are Fourier transformation of an astronomical image on the sky-plane, and incomple…