135 citations · 1.3k across the 68 of their papers we have counts for
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The 2015-2017 Large EVPA Rotation in OJ 287: Dominant Propagating Component in a Helical Magnetic Field with Time-Dependent Viewing Geometry
Wanchaloem Khwammai, Minchul Kam, Motoki Kino +11
We present high-cadence, multi-frequency monitoring of the blazar OJ 287 using KVN (22--129 GHz), ALMA (91.5--343.5 GHz), and Metsähovi (37 GHz), covering 2012--2023, together with…
Discovery of Limb Brightening in the Parsec-scale Jet of NGC 315 through Global Very Long Baseline Interferometry Observations and Its Implications for Jet Models
Jongho Park, Guang-Yao Zhao, Masanori Nakamura +19
We report the first observation of the nearby giant radio galaxy NGC 315 using a global VLBI array consisting of 22 radio antennas located across five continents, including high-se…
Evidence for a toroidal magnetic field in the core of 3C 84
G. F. Paraschos, L. C. Debbrecht, J. A. Kramer +13
The spatial scales of relativistic radio jets, probed by relativistic magneto-hydrodynamic jet launching simulations (RMHDs) and by most very-long-baseline interferometry (VLBI) ob…
A study of the radio spectrum of Mrk 421
Jee Won Lee, Sang-Sung Lee, Jeffrey Hodgson +5
We present the results of a spectral analysis using simultaneous multifrequency (22, 43, 86, and 129 GHz) very long baseline interferometry (VLBI) observations of the Korean VLBI N…
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…
Lost in the curve: Investigating the disappearing knots in the blazar 3C 454.3
Efthalia Traianou, Thomas P. Krichbaum, José L. Gómez +21
One of the most well-known extragalactic sources in the sky, quasar 3C 454.3, shows a curved parsec-scale jet that has been exhaustively monitored with very-long-baseline interfero…
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…
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…
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…
Jet kinematics in the transversely stratified jet of 3C 84 A two-decade overview
G. F. Paraschos, T. P. Krichbaum, J. -Y. Kim +11
3C84 (NGC1275) is one of the brightest radio sources in the mm radio-bands, which led to a plethora of VLBI observations at numerous frequencies over the years. They reveal a two-s…
The intrinsic structure of Sagittarius A* at 1.3 cm and 7 mm
Ilje Cho, Guang-Yao Zhao, Tomohisa Kawashima +63
Sagittarius A* (Sgr A*), the Galactic Center supermassive black hole (SMBH), is one of the best targets to resolve the innermost region of SMBH with very long baseline interferomet…
Magnetic Field Strengths of the Synchrotron Self-Absorption Region in the Jet of CTA 102 During Radio Flares
Sang-Hyun Kim, Sang-Sung Lee, Jee Won Lee +15
CTA 102 is a blazar implying that its relativistic jet points towards Earth and emits synchrotron radiation produced by energetic particles gyrating in the magnetic field. This stu…
Interferometric Monitoring of Gamma-ray Bright AGNs: Measuring the Magnetic Field Strength of 4C +29.45
S. Kang, S. -S. Lee, J. Hodgson +7
We present the results of multi-epoch, multi-frequency monitoring of a blazar 4C +29.45, which was regularly monitored as part of the Interferometric Monitoring of GAmma-ray Bright…
A detailed kinematic study of 3C 84 and its connection to Gamma-rays
Jeffrey A. Hodgson, Bindu Rani, Junghwan Oh +7
3C 84 (NGC 1275) is the bright radio core of the Perseus Cluster. Even in the absence of strong relativistic effects, the source has been detected at Gamma-rays up to TeV energies.…
The jet collimation profile at high resolution in BL Lacertae
C. Casadio, N. R. MacDonald, B. Boccardi +14
Controversial studies on the jet collimation profile of BL Lacertae (BL Lac), the eponymous blazar of BL Lac objects class, complicate the scenario in this already puzzling class o…
Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016
H. E. S. S. Collaboration, H. Abdalla, R. Adam +430
The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, GeV…
Kinematics of the M87 jet in the collimation zone: gradual acceleration and velocity stratification
Jongho Park, Kazuhiro Hada, Motoki Kino +36
We study the kinematics of the M87 jet using the first year data of the KVN and VERA Array (KaVA) large program, which has densely monitored the jet at 22 and 43 GHz since 2016. We…
Ejection of Double knots from the radio core of PKS 1510--089 during the strong gamma-ray flares in 2015
Jongho Park, Sang-Sung Lee, Jae-Young Kim +8
PKS 1510--089 is a bright and active -ray source that showed strong and complex -ray flares in mid-2015 during which the Major Atmospheric Gamma Imaging Cherenkov telescopes…
High-Energy Polarimetry - a new window to probe extreme physics in AGN jets
B. Rani, H. Zhang, S. D. Hunter +31
The constantly improving sensitivity of ground-based and space-borne observatories has made possible the detection of high-energy emission (X-rays and gamma-rays) from several thou…
The magnetic field structure in CTA 102 from high resolution mm-VLBI observations during the flaring state in 2016-2017
Carolina Casadio, Alan P. Marscher, Svetlana G. Jorstad +14
Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to shed light on the crucial physical processes giving rise to the jet forma…
Nustar view of the central region of the Perseus cluster
B. Rani, G. M. Madejski, R. F. Mushotzky +2
Located at the center of the Perseus cluster, 3C 84 is an extremely bright and nearby radio galaxy. Because of the strong diffuse thermal emission from the cluster in X-rays, the d…
Revealing the Nature of Blazar Radio Cores through Multi-Frequency Polarization Observations with the Korean VLBI Network
Jongho Park, Minchul Kam, Sascha Trippe +13
We study the linear polarization of the radio cores of eight blazars simultaneously at 22, 43, and 86 GHz with observations obtained by the Korean VLBI Network (KVN) in three epoch…
Exploring the Variability of the Flat Spectrum Radio Source 1633+382. II: Physical Properties
Juan-Carlos Algaba, Sang-Sung Lee, Bindu Rani +13
The flat spectrum radio quasar 1633+382 (4C~38.41) showed a significant increase of its radio flux density during the period 2012 March - 2015 August which correlates with gamma-ra…
Gamma-rays in the radio galaxy 3C 84: A complex situation
Jeffrey A. Hodgson, Bindu Rani, Junghwan Oh
3C 84 is a nearby Active Galactic Nucleus (AGN) that is unique in that is believed that we are observing near the true jet launching region - unlike blazars. The source is active i…