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Observational Evidence to Support a Dense Ambient Medium Shaping the Jet in 3C 84
Jongho Park, Motoki Kino, Hiroshi Nagai +4
Highly collimated relativistic jets are a defining feature of certain active galactic nuclei (AGN), yet their formation mechanism remains elusive. Previous observations and theoret…
Evolution of the Termination Region of the Parsec-Scale Jet of 3C 84 Over the Past 20 Years
Minchul Kam, Jeffrey A. Hodgson, Jongho Park +4
We present the kinematics of the parsec-scale jet in 3C 84 from 2003 November to 2022 June observed with the Very Long Baseline Array (VLBA) at 43 GHz. We find that the C3 componen…
First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization
The Event Horizon Telescope Collaboration
Event Horizon Telescope (EHT) observations have revealed a bright ring of emission around the supermassive black hole at the center of the M87 galaxy. EHT images in linear polariza…
Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes
Freek Roelofs, Michael D. Johnson, Andrew Chael +4
The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagit…
First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
The Event Horizon Telescope Collaboration
Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies…
First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
The Event Horizon Telescope Collaboration
We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr…
First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
The Event Horizon Telescope Collaboration
In this paper, we provide a first physical interpretation for the Event Horizon Telescope (EHT)'s 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at…
First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
The Event Horizon Telescope Collaboration
We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A), the Galactic center source associated with a supermassive black hole. These observati…
First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
The Event Horizon Telescope Collaboration
In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. W…
Precessing jet nozzle connecting to a spinning black hole in M87
Yuzhu Cui, Kazuhiro Hada, Tomohisa Kawashima +76
The nearby radio galaxy M87 offers a unique opportunity to explore the connections between the central supermassive black hole and relativistic jets. Previous studies of the inner…
Calibrating VLBI Polarization Data Using GPCAL. II. Time-Dependent Calibration
Jongho Park, Keiichi Asada, Do-Young Byun
We present a new method of time-dependent instrumental polarization calibration for Very Long Baseline Interferometry (VLBI). This method has been implemented in the recently devel…
Calibrating VLBI Polarization Data Using GPCAL. I. Frequency-Dependent Calibration
Jongho Park, Keiichi Asada, Do-Young Byun
In this series of papers, we present new methods of frequency- and time-dependent instrumental polarization calibration for Very Long Baseline Interferometry (VLBI). In most existi…
A search for pulsars around Sgr A* in the first Event Horizon Telescope dataset
Pablo Torne, Kuo Liu, Ralph P. Eatough +282
The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz (=1.3 mm). Th…
Double SSA Spectrum and Magnetic Field Strength of the FSRQ 3C 454.3
Hyeon-Woo Jeong, Sang-Sung Lee, Whee Yeon Cheong +7
We present the results of a radio multi-frequency () study of the blazar 3C~454.3. After subtracting the quiescent spectrum corresponding to optically thin emission,…
Probing the Heart of Active Narrow-line Seyfert 1 Galaxies with VERA Wideband Polarimetry
Mieko Takamura, Kazuhiro Hada, Mareki Honma +9
We explored the parsec-scale nuclear regions of a sample of radio-loud narrow-line Seyfert 1 galaxies (NLSy1s) using the VLBI Exploration of Radio Astronomy (VERA) wideband (at a r…
A ring-like accretion structure in M87 connecting its black hole and jet
Ru-Sen Lu, Keiichi Asada, Thomas P. Krichbaum +118
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…
The Capella Program: Toward A Space-only High-frequency Radio VLBI Network Formed by Small Satellites in Low Earth Orbits
Sascha Trippe, Taehyun Jung, Jung-Won Lee +11
Very long baseline radio interferometry (VLBI) with ground-based observatories is limited by the size of Earth, the geographic distribution of antennas, and the transparency of the…
Spectral analysis of a parsec-scale jet in M87: Observational constraint on the magnetic field strengths in the jet
Hyunwook Ro, Motoki Kino, Bong Won Sohn +49
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, magne…
Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration
Cora Prather, Jason Dexter, Monika Moscibrodzka +270
Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrume…
The Event Horizon Telescope Image of the Quasar NRAO 530
Svetlana Jorstad, Maciek Wielgus, Rocco Lico +27
We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5-7, when NRAO 530 was used as a calibrator for the EHT observations of Sa…