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Black Hole Explorer Mission Development in Japan
Kazunori Akiyama, Mareki Honma, Akihiro Doi +21
The Black Hole Explorer (BHEX) is a next-generation space very-long-baseline interferometry (VLBI) mission concept that will extend existing ground-based millimeter/submillimeter V…
First Very Long Baseline Interferometry Detections at 870μm
Alexander W. Raymond, Sheperd S. Doeleman, Keiichi Asada +276
The first very long baseline interferometry (VLBI) detections at 870m wavelength (345GHz frequency) are reported, achieving the highest diffraction-limited angular resolutio…
The Black Hole Explorer: Instrument System Overview
Daniel P. Marrone, Janice Houston, Kazunori Akiyama +14
The Black Hole Explorer (BHEX) is a space very-long-baseline interferometry (VLBI) mission concept that is currently under development. BHEX will study supermassive black holes at…
The Black Hole Explorer Cryocooling Instrument
Hannah Rana, Kazunori Akiyama, Edgar Canavan +10
The Black Hole Explorer (BHEX) is a space-based very-long baseline interferometry (VLBI) mission aimed at precision black hole measurements, detecting the photon ring around black…
The Black Hole Explorer: Motivation and Vision
Michael D. Johnson, Kazunori Akiyama, Rebecca Baturin +65
We present the Black Hole Explorer (BHEX), a mission that will produce the sharpest images in the history of astronomy by extending submillimeter Very-Long-Baseline Interferometry…
The Black Hole Explorer: Operating a Hybrid Observatory
Sara Issaoun, Kim Alonso, Kazunori Akiyama +16
We present a baseline science operations plan for the Black Hole Explorer (BHEX), a space mission concept aiming to confirm the existence of the predicted sharp ``photon ring" resu…
Receivers for the Black Hole Explorer (BHEX) Mission
C. Edward Tong, Kazunori Akiyama, Paul Grimes +6
In this paper, we introduce the receiver architecture for the Black Hole Explorer (BHEX) Mission, designed to reveal the photon ring of black holes. The primary instrument is a dua…
The Japanese Vision for the Black Hole Explorer Mission
Kazunori Akiyama, Kotaro Niinuma, Kazuhiro Hada +43
The Black Hole Explorer (BHEX) is a next-generation space very long baseline interferometry (VLBI) mission concept that will extend the ground-based millimeter/submillimeter arrays…
Enabling Transformational ngEHT Science via the Inclusion of 86 GHz Capabilities
Sara Issaoun, Dominic W. Pesce, Freek Roelofs +13
We present a case for significantly enhancing the utility and efficiency of the ngEHT by incorporating an additional 86 GHz observing band. In contrast to 230 or 345 GHz, weather c…
The Haystack Telescope as an Astronomical Instrument
Jens Kauffmann, Ganesh Rajagopalan, Kazunori Akiyama +4
The Haystack Telescope is an antenna with a diameter of 37~m and an elevation-dependent surface accuracy of that is capable of millimeter-wave observations. The…
Millimeter/submillimeter VLBI with a Next Generation Large Radio Telescope in the Atacama Desert
Kazunori Akiyama, Jens Kauffmann, Lynn D. Matthews +3
The proposed next generation Event Horizon Telescope (ngEHT) concept envisions the imaging of various astronomical sources on scales of microarcseconds in unprecedented detail with…
Overview of the Observing System and Initial Scientific Accomplishments of the East Asian VLBI Network (EAVN)
Kazunori Akiyama, Juan-Carlos Algaba, Tao An +101
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 Southe…
Evaluation of the ngVLA Revision D array configuration for stellar imaging
Catherine G. Petretti, Kazunori Akiyama, Lynn D. Matthews
A transformative science case for the proposed next-generation Very Large Array (ngVLA) is resolving the surfaces of nearby stars, both spatially and temporally, enabled by the com…
New Views of Black Holes from Computational Imaging
Kazunori Akiyama, Andrew Chael, Dominic W. Pesce
The unique challenges associated with imaging a black hole motivated the development of new computational imaging algorithms. As the Event Horizon Telescope continues to expand, th…
SYMBA: An end-to-end VLBI synthetic data generation pipeline
F. Roelofs, M. Janssen, I. Natarajan +203
Realistic synthetic observations of theoretical source models are essential for our understanding of real observational data. In using synthetic data, one can verify the extent to…
Studying black holes on horizon scales with space-VLBI
Kari Haworth, Michael D. Johnson, Dominic W. Pesce +25
The Event Horizon Telescope (EHT) recently produced the first horizon-scale image of a supermassive black hole. Expanding the array to include a 3-meter space telescope operating a…
Studying Black Holes on Horizon Scales with VLBI Ground Arrays
Lindy Blackburn, Sheperd Doeleman, Jason Dexter +35
High-resolution imaging of supermassive black holes is now possible, with new applications to testing general relativity and horizon-scale accretion and relativistic jet formation…
First M87 Event Horizon Telescope Results. II. Array and Instrumentation
The Event Horizon Telescope Collaboration
The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comp…
Source-Frequency Phase-Referencing Observation of AGNs with KaVA Using Simultaneous Dual-Frequency Receiving
Guang-Yao Zhao, Taehyun Jung, Bong Won Sohn +27
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 interfer…
Imaging Black Holes and Jets with a VLBI Array Including Multiple Space-Based Telescopes
Vincent L. Fish, Maura Shea, Kazunori Akiyama
Very long baseline interferometry (VLBI) from the ground at millimeter wavelengths can resolve the black hole shadow around two supermassive black holes, Sagittarius A* and M87. Th…
EHT-HOPS pipeline for millimeter VLBI data reduction
Lindy Blackburn, Chi-kwan Chan, Geoffrey B. Crew +12
We present the design and implementation of an automated data calibration and reduction pipeline for very-long-baseline interferometric (VLBI) observations taken at millimeter wave…
Faraday Tomography with Sparse Modeling
Kazunori Akiyama, Takuya Akahori, Yoshimitsu Miyashita +4
Faraday tomography (or rotation measure synthesis) is a procedure to convert linear polarization spectra into the Faraday dispersion function, which provides us with unique informa…
Interferometric Imaging Directly with Closure Phases and Closure Amplitudes
Andrew A. Chael, Michael D. Johnson, Katherine L. Bouman +3
Interferometric imaging now achieves angular resolutions as fine as 10 microarcsec, probing scales that are inaccessible to single telescopes. Traditional synthesis imaging methods…
Superresolution Interferometric Imaging with Sparse Modeling Using Total Squared Variation --- Application to Imaging the Black Hole Shadow
Kazuki Kuramochi, Kazunori Akiyama, Shiro Ikeda +5
We propose a new superresolution imaging technique for interferometry using sparse modeling, utilizing two regularization terms: the -norm and a new function named Total Sq…