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Universal Polarimetric Signatures of the Black Hole Photon Ring

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arxiv 2001.08750 v1 pith:R7M2MS3T submitted 2020-01-23 gr-qc astro-ph.HEhep-th

Elizabeth Himwich , Michael D. Johnson , Alexandru Lupsasca , Andrew Strominger This is my paper · ORCID
classification gr-qcastro-ph.HEhep-th
keywords blackholephotonringuniversalpolarimetricsignaturesspin
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Black hole images present an annular region of enhanced brightness. In the absence of propagation effects, this "photon ring" has universal features that are completely governed by general relativity and independent of the details of the emission. Here, we show that the polarimetric image of a black hole also displays universal properties. In particular, the photon ring exhibits a self-similar pattern of polarization that encodes the black hole spin. We explore the corresponding universal polarimetric signatures of the photon ring on long interferometric baselines, and propose a method for measuring the black hole spin using a sparse interferometric array. These signatures could enable spin measurements of the supermassive black hole in M87, as well as precision tests of general relativity in the strong field regime, via a future extension of the Event Horizon Telescope to space.

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Cited by 5 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Polarization Signatures of Inspiraling Hotspots around Kerr Black Holes

    astro-ph.HE 2026-02 unverdicted novelty 7.0 of 10

    Inspiraling hotspots near Kerr black holes produce precessing, unwinding Stokes Q-U polarization loops, unlike the closed loops of stable circular orbits.

  2. The glow of eternal black holes

    gr-qc 2026-08 accept novelty 6.0 of 10

    An eternal Schwarzschild black hole with an emitting surface at r=r_m would show a bright spot inside its shadow, whose interferometric visibility decays exponentially with baseline length.

  3. Dark matter environments and safeguards for spacetime inference from horizon scale interferometry

    gr-qc 2026-07 conditional novelty 6.0 of 10

    Using public 2017 M87* closure data, a frozen Kerr source fails an absolute adequacy test and the differential tidal-charge response fails numerical convergence, so no posterior or bound is reported.

  4. Semi-analytical Study on the Polarized Images of Black Hole due to Frame Dragging

    gr-qc 2025-08 unverdicted novelty 5.0 of 10

    Frame dragging flips an initially retrograde equatorial flow around a Kerr black hole, and the polarized image shows three distinct critical locations whose spatial hierarchy is derived analytically for an on-axis observer.

  5. Testing Extended Theories of Gravity via Black Hole Photon Rings

    gr-qc 2025-05 conditional novelty 3.0 of 10

    For Konoplya-Zhidenko deformed Schwarzschild black holes, epsilon controls photon sphere, shadow, and photon ring size while a2 and b2 are observationally degenerate, and EHT data constrain epsilon to about -0.09 to 0...

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