Black Hole Explorer (BHEX) is a space VLBI mission concept, which can probe the black hole spacetime and the plasma properties including the magnetic fields of the accretion flows and relativistic jets. We propose scientific inquiries anticipated to be addressed by EHE, primarily through the imaging of microarcsecond-scale signatures in target sources. An appearance of a crescent-shaped shadow in a bright state of the M87 will enable us to constrain the magnitude of the black hole spin (Kawashima et al. 2019). A possible appearance of the plasma injection region in the vicinity of the black hole results in the formation of the multiple ring structure and may enable us to understand the jet formation processes (Kawashima et al. 2021, and Ogihara et al. submitted to ApJ). In addition, the reversal of the sign of the circular polarization and the separation of linear and circular polarization flux peaks will constrain the magnetic field structure and the thermal properties of the electrons, respectively (Tsunetoe et al. 2021, 2022). Other topics, including potential scientific inquiries of luminous active galactic nuclei, will be also discussed.
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 (VLBI) to space. BHEX will discover and measure the bright and narrow “photon ring” that is predicted to exist in images of black holes, produced from light that has orbited the black hole before escaping. This discovery will expose universal features of a black hole’s spacetime that are distinct from the complex astrophysics of the emitting plasma, allowing the first direct measurements of a supermassive black hole’s spin. In addition to studying the properties of the nearby supermassive black holes M87∗ and Sgr A∗ , BHEX will measure the properties of dozens of additional supermassive black holes, providing crucial insights into the processes that drive their creation and growth. BHEX will also connect these supermassive black holes to their relativistic jets, elucidating the power source for the brightest and most efficient engines in the universe. BHEX will address fundamental open questions in the physics and astrophysics of black holes that cannot be answered without submillimeter space VLBI. The mission is enabled by recent technological breakthroughs, including the development of ultra-high-speed downlink using laser communications, and it leverages billions of dollars of existing ground infrastructure. We present the motivation for BHEX, its science goals and associated requirements, and the pathway to launch within the next decade.
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 into space. The mission, closely aligned with the science priorities of the Japanese VLBI community, involves an active engagement of this community in the development of the mission, resulting in the formation of the Black Hole Explorer Japan Consortium. Here we present the current Japanese vision for the mission, ranging from scientific objectives to instrumentation. The Consortium anticipates a wide range of scientific investigations, from diverse black hole physics and astrophysics studied through the primary VLBI mode, to the molecular universe explored via a potential single-dish observation mode in the previously unexplored 50-70 GHz band that would make BHEX the highest-sensitivity explorer ever of molecular oxygen. A potential major contribution for the onboard instrument involves supplying essential elements for its high-sensitivity dual-band receiving system, which includes a broadband 300 GHz SIS mixer and a space-certified multi-stage 4.5K cryocooler akin to those used in the Hitomi and XRISM satellites by the Japan Aerospace Exploration Agency. Additionally, the Consortium explores enhancing and supporting BHEX operations through the use of millimeter/submillimeter facilities developed by the National Astronomical Observatory of Japan, coupled with a network of laser communication stations operated by the National Institute of Information and Communication Technology.
VLBI Exploration of Radio Astrometry (VERA) is a VLBI facility operated by the National Astronomical Observatory of Japan. It comprises four 20 m radio telescopes located across the country. VLBI observations at 86 GHz allow us to explore the jet base of nearby active galactic nuclei. In recent years, the development of the 86 GHz receiver systems at the East Asia VLBI Network (EAVN) has started. Currently, only three Korea VLBI Network (KVN) antennas provide 86 GHz VLBI capability in the member stations of EAVN. The participation of VERA in the 86 GHz VLBI observations will boost resolution, sensitivity, and dynamic range. Therefore, we are developing a new 86 GHz low noise receiver system to be installed at VERA Mizusawa and Ishigaki stations. We are considering a cooled circular polarization receiver covering a wide frequency range of 67−116 GHz with the capability of cooling HEMT amplifiers. We are developing a room temperature 2 side band (2SB) system for down-converting signals in the 67−116 GHz band. Recently developed room-temperature mixers with an IF frequency over 25 GHz could cover most of the 67−116 GHz RF signals in a single observation. In this poster, we will discuss the development progress of the 2SB receiver and the design status of the cooling Dewar.
The new VLBI data acquisition system (OCTAVE-DAS) have been developed for VLBI Exploration of Radio Astrometry (VERA) and the East Asia VLBI Network (EAVN) based on the VSI-H and VDIF specifications at the National Astronomical Observatory of Japan. It consists of 1) a high speed 1-20 Gsps 3-10 bit RF(-30 GHz) direct sampler with DBBC functions, 2) media converter between one 10 GigE port and four 2 Gbps input and output ports conformable to VSI-H, 3) new VLBI recorders have functions of both recording and playing at a maximum rate of 32 Gbps and 4) Gbit real-time correlator and software correlator system using GPGPU technology. These OCTAVE-DAS instruments are connected via 10 GigE network with VDIF and VSI specifications. These components have been used for VERA, Japanese VLBI Network (JVN) and EAVN. We will report on current status and results of scientific broad-band (16 Gbps) VLBI test observation using the OCTAVE-DAS.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.