A study collided by the Institute of Astrophysics of Andalusia (IAA-CSIC) revealed that the ellipticity of the M87 galaxy ring, located about 55 million light years from the earth, is due to the turbulence of the plasma that surrounds it and not at its rotation speed on its own axis, known as spin.
This galaxy houses the supermassive black hole M87*in its nucleus, whose image turned the world in 2019 thanks to the Telescope of the Event Horizon (EHT), reports the Andalusian Institute of Astrophysics.
That historical photography revealed a luminous ring around M87* with a slightly elongated form that raised questions such as why it is not perfectly circular.
Astronomy & Astrophysics magazine now published a study collided by the Institute of Astrophysics of Andalusia that sheds light on this issue.
Rohan Dahale, an IAA -CSIC researcher and main co -author of the work, explains that the study showed that the slightly elongated form of the ring is not caused by gravity or by the turn -Spin- of the black hole, but by turbulent astrophysical processes in the plasma that surrounds it.
Einstein’s general relativity theory predicts that the shadow of a black hole in rotation is slightly stocked, adopting an elliptical shape as a consequence of the distortion of the space-time caused by its spin.
Quantifying this ellipticity constitutes a direct route to estimate the black hole spin, one of the two parameters that, together with the dough, completely define their appearance and physical properties, says the researcher.
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Beyond the perfect circle in the black hole M87
To refine this measure, the scientific team incorporated in 2018 the Greenland telescope into the EHT stations network, increasing the spatial resolution and the sensitivity of collaboration, which tripled with respect to previous campaigns.
Using five independent algorithms of image reconstruction based on opening synthesis techniques, it could be consistently verified that it departs from a perfect circle in approximately 8%.
They also discovered that this ellipse is turned around 50 ° in an anti -Horary sense with respect to the north, aligned approximately with the brightest point in the ring.
To find out if the severity alone could explain that elongated form, the team compared the real images with a series of computer simulations that explored different physical scenarios, including several spin values for the black hole.
The scientists did not find a clear relationship between the spin and the ellipse in the simulated images. Instead, they discovered that the elongated form of the ring went hand in hand with what they call “non -annular emission”: a diffuse glow that surrounds the main ring, more intense in those models with very energy electrons and with a jet of matter -Jet- most bright.
Ilje Cho, from the University of Yensei (South Korea) and main co -author of the study, clarifies that “these results suggest that the ellipticality of M87* is, above all, a trace of the turbulent plasma that revolves around the black hole, and not a direct reflection of its gravitational force or its rotation speed”.
“Thus we can better separate the role of the severity of astrophysical processes when forming these incredible images, and taking another step towards understanding how matter behaves in the most extreme environments of the universe, he explains.
Although measuring the spin of M87* In the presence of so much turbulence it is a great challenge, the team proposes to advance through two complementary pathways: on the one hand, to make sustained observations over the years and on the other, to launch telescopes in orbit that, by means black hole and wears a purer gravitational signal, ideal to measure the spin.
With EFE information
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