# Photon rings of spherically symmetric black holes and robust tests of non-Kerr metrics

@article{Wielgus2021PhotonRO, title={Photon rings of spherically symmetric black holes and robust tests of non-Kerr metrics}, author={Maciek Wielgus}, journal={Physical Review D}, year={2021} }

Under very general assumptions on the accretion flow geometry, images of a black hole illuminated by electromagnetic radiation display a sequence of photon rings (demagnified and rotated copies of the direct image) which asymptotically approach a purely theoretical critical curve – the outline of the black hole photon shell. To a distant observer, these images appear dominated by the direct emission, which forms a ring whose diameter is primarily determined by the effective radius of the…

## 6 Citations

Universal signatures of singularity-resolving physics in photon rings of black holes and horizonless objects

- Physics
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. Within quantum-gravity approaches and beyond, diﬀerent mechanisms for singularity resolution in black holes exist. Under a set of assumptions that we spell out in detail, these mechanisms leave…

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The observation of the shadow of the supermassive black hole M87∗ by the Event Horizon Telescope (EHT) is sensitive to the spacetime geometry near the circular photon orbit and beyond, and it thus…

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Gennady S. Bisnovatyi-Kogan 3, ∗ and Oleg Yu. Tsupko † Space Research Institute of Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117997, Russia National Research Nuclear University MEPhI…

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We study gravitational lensing of light by hairy black holes, which, in a certain parameter regime, can possess two photon spheres of diﬀerent size outside the event horizon. In particular, we focus…

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- Physics
- 2022

We study the lensing eﬀects of Kerr-Newman (KN) black holes and the multi-level images of luminous sources around the black holes. We obtain the analytic forms of the lens equations in KN spacetime…

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## References

SHOWING 1-10 OF 112 REFERENCES

Lensing by Kerr black holes

- PhysicsPhysical Review D
- 2020

Interpreting horizon-scale observations of astrophysical black holes demands a general understanding of null geodesics in the Kerr spacetime. These may be divided into two classes: "direct" rays that…

Observing the Inner Shadow of a Black Hole: A Direct View of the Event Horizon

- PhysicsThe Astrophysical Journal
- 2021

Simulated images of a black hole surrounded by optically thin emission typically display two main features: a central brightness depression and a narrow “photon ring” consisting of strongly lensed…

Image of a spherical black hole with thin accretion disk.

- Physics
- 1979

Black hole accretion disks are currently a topic of widespread interest in astrophysics and are supposed to play an important role in a number of high-energy situations. An investigation of the…

A Parametric Model for the Shapes of Black Hole Shadows in Non-Kerr Spacetimes

- Physics
- 2019

The Event Horizon Telescope (EHT) is taking the first images of black holes resolved at horizon scales to measure their shadows and probe accretion physics. A promising avenue for testing the…

The Shadow of a Spherically Accreting Black Hole

- PhysicsThe Astrophysical Journal
- 2019

We explore a simple spherical model of optically thin accretion on a Schwarzschild black hole, and study the properties of the image as seen by a distant observer. We show that a dark circular region…

Shadow of the regular Bardeen black holes and comparison of the motion of photons and neutrinos

- PhysicsThe European Physical Journal C
- 2019

The aim of the present research is the analysis of the photon motion in the regular spacetimes arising as solutions of the Einstein gravity coupled with a non-linear electrodynamics (NED). The…

Viewing the Shadow of the Black Hole at the Galactic Center.

- Physics
- 2000

In recent years, evidence for the existence of an ultracompact concentration of dark mass associated with the radio source Sagittarius A* in the Galactic center has become very strong. However,…

Measuring Spin from Relative Photon-ring Sizes

- Physics
- 2022

The direct detection of a bright, ring-like structure in horizon-resolving images of M87* by the Event Horizon Telescope (EHT) is a striking validation of general relativity. The angular size and…

Universal interferometric signatures of a black hole’s photon ring

- PhysicsScience Advances
- 2020

This work shows that a thin “photon ring” composed of an infinite sequence of self-similar subrings that are indexed by the number of photon orbits around the black hole produces strong and universal signatures on long interferometric baselines, which offer the possibility of precise measurements of black hole mass and spin.

First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole

- PhysicsThe Astrophysical Journal
- 2019

When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study…