1.9k citations · 17.5k across the 116 of their papers we have counts for
9 papers · 1 filter
Accelerating cross-validation with total variation and its application to super-resolution imaging
Tomoyuki Obuchi, Shiro Ikeda, Kazunori Akiyama +1
We develop an approximation formula for the cross-validation error (CVE) of a sparse linear regression penalized by -norm and total variation terms, which is based on a per…
Reconstruction of Static Black Hole Images Using Simple Geometric Forms
Leonid Benkevitch, Kazunori Akiyama, Rusen Lu +2
General Relativity predicts that the emission close to a black hole must be lensed by its strong gravitational field, illuminating the last photon orbit. This results in a dark cir…
The Effects of Accretion Flow Dynamics on the Black Hole Shadow of Sagittarius A
Hung-Yi Pu, Kazunori Akiyama, Keiichi Asada
A radiatively inefficient accretion flow (RIAF), which is commonly characterized by its sub-Keplerian nature, is a favored accretion model for the supermassive black hole at Galact…
Observing---and Imaging---Active Galactic Nuclei with the Event Horizon Telescope
Vincent L. Fish, Kazunori Akiyama, Katherine L. Bouman +7
Originally developed to image the shadow region of the central black hole in Sagittarius A* and in the nearby galaxy M87, the Event Horizon Telescope (EHT) provides deep, very high…
EVN Observations of HESS J1943+213: Evidence for an Extreme TeV BL Lac Object
Kazunori Akiyama, Łukasz Stawarz, Yasuyuki T. Tanaka +3
We report on the 1.6 GHz (18 cm) VLBI observations of the unresolved, steady TeV source HESS J1943+213 located in the Galactic plane, performed with the European VLBI Network (EVN)…
PRECL: A new method for interferometry imaging from closure phase
Shiro Ikeda, Fumie Tazaki, Kazunori Akiyama +2
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 situatio…
Interstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB150418
Kazunori Akiyama, Michael D. Johnson
Keane et al. (2016) have recently reported the discovery of a new fast radio burst, FRB150418, with a promising radio counterpart at 5.5 and 7.5 GHz -- a rapidly decaying source, f…
Modeling Seven Years of Event Horizon Telescope Observations with Radiatively Inefficient Accretion Flow Models
Avery E. Broderick, Vincent L. Fish, Michael D. Johnson +6
An initial three-station version of the Event Horizon Telescope, a millimeter-wavelength very-long baseline interferometer, has observed Sagittarius A* (Sgr A*) repeatedly from 200…
Persistent Asymmetric Structure of Sagittarius A* on Event Horizon Scales
Vincent L. Fish, Michael D. Johnson, Sheperd S. Doeleman +69
The Galactic Center black hole Sagittarius A* (Sgr A*) is a prime observing target for the Event Horizon Telescope (EHT), which can resolve the 1.3 mm emission from this source on…