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Probing Axions with Event Horizon Telescope Polarimetric Measurements

6 Pith papers cite this work. Polarity classification is still indexing.

6 Pith papers citing it
abstract

With high spatial resolution, polarimetric imaging of a supermassive black hole, like M87$^\star$ or Sgr A$^\star$, by the Event Horizon Telescope can be used to probe the existence of ultralight bosonic particles, such as axions. Such particles can accumulate around a rotating black hole through the superradiance mechanism, forming an axion cloud. When linearly polarized photons are emitted from an accretion disk near the horizon, their position angles oscillate due to the birefringent effect when traveling through the axion background. In particular, the observations of supermassive black holes M87$^\star$ (Sgr A$^\star$) can probe the dimensionless axion-photon coupling $c = 2 \pi g_{a \gamma} f_a$ for axions with mass around $O(10^{-20})$~eV ($O( 10^{-17}$)~eV) and decay constant $f_a < O(10^{16})$ GeV, which is complimentary to other axion measurements.

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2026 4 2025 2

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representative citing papers

Stellar Superradiance and Low-Energy Absorption in Dense Nuclear Media

hep-ph · 2025-12-15 · unverdicted · novelty 6.0

Collective nucleon scattering in neutron-star matter suppresses the effective absorption of ultralight bosons at the long wavelengths relevant for superradiance, weakening the link between stellar cooling bounds and superradiant instability rates.

Gravitational Atoms from Topological Stars

gr-qc · 2025-11-13 · unverdicted · novelty 5.0

Bound states of a massive scalar field around topological stars form strictly normal modes, producing a hydrogen-like spectrum when the Compton wavelength exceeds the star size and localized states otherwise.

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Showing 6 of 6 citing papers.