Supermassive black hole M87*: Magnetic fields are surprisingly turbulent
The supermassive black hole M87* was the first to be photographed. Now there are more images of the object and they show surprising changes.
The three images including the indication of the polarization
(Image: EHT-Kollaboration)
The polarization of light from the supermassive black hole at the center of the galaxy Messier 87 (M87) has unexpectedly reversed between 2017 and 2021, and the dynamics now discovered “push our theoretical models to their limits.” This is what astronomer Paul Tiede from the Center for Astrophysics, Harvard & Smithsonian says about the classification of new images of the object that have now been presented. These show the supermassive black hole M87* for mid-April 2017, 2018, and 2021, including the polarization of the underlying light. On the one hand, they clearly show the stability of the object's shadow as predicted by Albert Einstein, but at the same time reveal surprising turbulence in the magnetic fields, explains the Max Planck Institute for Radio Astronomy.
Enormously dynamic magnetic fields
(Image:Â EHT-Kollaboration)
The new images were taken by the Event Horizon Telescope, a global network of telescopes that can be interconnected and simultaneously pointed at the black hole. This enabled the historic first-ever direct image of a black hole to be taken in 2017. The iconic image shows the immediate surroundings of the black hole in the center of M87, 55 million light-years away. Later, the measurement data on the polarization of the light was added, and now there are already three images that combine this data. The large differences between the complicated polarization patterns are immediately apparent. These indicate the enormous dynamics of the magnetic fields there.
While the direction of oscillation of individual light waves is normally random, polarized light waves oscillate in one plane. Such polarization can be achieved by filters (for example, in sunglasses) or by strong magnetic fields at the light source. The measured polarization therefore provides a clearer view of the black hole of M87 and, above all, of the magnetic fields there. The three images indicate “an evolving, turbulent environment in which magnetic fields play a crucial role in how matter falls into the black hole and how energy is channeled into the outward-facing jet,” explains the Max Planck Institute. The surprising changes called existing models into question.
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However, it is also remarkable that the size of the ring has remained constant over the years, exactly as predicted by Albert Einstein's theories, adds Tiede. The multi-year images would therefore deepen our knowledge of one of the most extreme places in the universe and reveal an unexpected complexity. The next step is to work on more frequent images—ideally sufficient for a movie. The discovery is presented in the science magazine Astronomy & Astrophysics. Those responsible also point out that the Event Horizon Telescope has benefited “decisively” from the connection of two telescopes, one in the USA and one in the French Alps.
(mho)
