Measurement of the spin of the M87 black hole from its observed twisted light

By Fabrizio Tamburini, B. Thid'e, M. della Valle. Monthly Notices of the Royal Astronomical Society Letters, 2019

139 citations recorded by the source corpus.

We present the first observational evidence that light propagating near a rotating black hole is twisted in phase and carries orbital angular momentum (OAM). This physical observable allows a direct measurement of the rotation of the black hole. We extracted the OAM spectra from the radio intensity data collected by the Event Horizon Telescope from around the black hole M87* by using wavefront reconstruction and phase recovery techniques and from the visibility amplitude and phase maps. This method is robust and complementary to black hole shadow circularity analyses. It shows that the M87* rotates clockwise with an estimated rotation parameter a = 0.90 ± 0.05 with an $\sim 95{{\ \rm per\ cent}}$ confidence level (c.l.) and an inclination i = 17° ± 2°, equivalent to a magnetic arrested disc with an inclination i = 163° ± 2°. From our analysis, we conclude that, within a 6σ c.l., the M87* is rotating.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/50dd71da6fb3b357404e6fa3bd34c8bed7a7a1b0

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

Silhouette of M87*: A new window to peek into the world of hidden dimensions (2019, background): “However, a recent analysis [70] predicts the rotation parameter to be |a| ∼ 0.”
Testing the rotational nature of the supermassive object M87* from the circularity and size of its first image (2019, methodology): “These constraints are therefore complementary to those of [58].”
Black holes with scalar hair in light of the Event Horizon Telescope (2020, background): “However, most of the BHs we have observed, including M87*, carry spin [109].”