Resolving Nearby Supermassive Black Holes with the Black Hole Explorer
Abstract
Recent Event Horizon Telescope results have demonstrated unique and transformative science in gravitational physics and black hole astrophysics enabled by event-horizon-scale imaging of supermassive black holes (SMBHs). Nevertheless, the angular resolution of current ground-based very long baseline interferometry (VLBI) arrays limits such studies to only two sources, precluding systematic investigations of horizon-scale emission across a nearby SMBH population. The proposed Black Hole Explorer (BHEX), a millimeter/submillimeter space VLBI mission, would overcome this limitation by delivering substantially higher angular resolution. Here, we present a series of simulated observations to assess a population of nearby horizon-scale targets accessible with BHEX. Based on a recently developed SMBH number density model, we find that BHEX could infer black hole masses for ~70-90 sources from size measurements, constrain magnetic field structures through linear polarization imaging for ~20-30 sources, and resolve black hole shadows for ~20-25 sources. Targeted observations of ~50 nearby SMBHs are expected to yield measurements for ~30 source sizes and ~10 shadows and linear-polarization patterns. These projections are supported by detailed imaging simulations of general relativistic magnetohydrodynamic (GRMHD) models for eleven nearby SMBHs. Together, our results highlight BHEX as a powerful facility for revealing the demographics of SMBH properties across diverse accretion states, radio loudness, host galaxy environments, and viewing geometries.
Versions
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BibTeX
@misc{akiyama2026resolving,
title = {{Resolving Nearby Supermassive Black Holes with the Black Hole Explorer}},
author = {Yuto Akiyama and Kazunori Akiyama and Dominic W. Pesce and Daniel C. M. Palumbo and Angelo Ricarte and Paul Tiede and Marvin N. Martinez and Hikaru Yoshida and Avery E. Broderick and Aya E. Higuchi and Sara Issaoun and Neil M Nagar and Kotaro Niinuma and Venkatessh Ramakrishnan and Xinyue Alice Zhang},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.16983},
eprint = {2608.16983},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.16983},
}
RIS
TY - UNPB
TI - Resolving Nearby Supermassive Black Holes with the Black Hole Explorer
AU - Yuto Akiyama
AU - Kazunori Akiyama
AU - Dominic W. Pesce
AU - Daniel C. M. Palumbo
AU - Angelo Ricarte
AU - Paul Tiede
AU - Marvin N. Martinez
AU - Hikaru Yoshida
AU - Avery E. Broderick
AU - Aya E. Higuchi
AU - Sara Issaoun
AU - Neil M Nagar
AU - Kotaro Niinuma
AU - Venkatessh Ramakrishnan
AU - Xinyue Alice Zhang
PY - 2026
DA - 2026/08/17
PB - arXiv
DO - 10.48550/arxiv.2608.16983
UR - https://arxiv.org/abs/2608.16983
AB - Recent Event Horizon Telescope results have demonstrated unique and transformative science in gravitational physics and black hole astrophysics enabled by event-horizon-scale imaging of supermassive black holes (SMBHs). Nevertheless, the angular resolution of current ground-based very long baseline interferometry (VLBI) arrays limits such studies to only two sources, precluding systematic investigations of horizon-scale emission across a nearby SMBH population. The proposed Black Hole Explorer (BHEX), a millimeter/submillimeter space VLBI mission, would overcome this limitation by delivering substantially higher angular resolution. Here, we present a series of simulated observations to assess a population of nearby horizon-scale targets accessible with BHEX. Based on a recently developed SMBH number density model, we find that BHEX could infer black hole masses for ~70-90 sources from size measurements, constrain magnetic field structures through linear polarization imaging for ~20-30 sources, and resolve black hole shadows for ~20-25 sources. Targeted observations of ~50 nearby SMBHs are expected to yield measurements for ~30 source sizes and ~10 shadows and linear-polarization patterns. These projections are supported by detailed imaging simulations of general relativistic magnetohydrodynamic (GRMHD) models for eleven nearby SMBHs. Together, our results highlight BHEX as a powerful facility for revealing the demographics of SMBH properties across diverse accretion states, radio loudness, host galaxy environments, and viewing geometries.
ER -