Also make mistakes serve: by chance using a technique of “double gravitational zoom” has been observed the crown of a black hole with a detail never seen.

A group of astronomers was able to see, with unprecedented sharpness, the crown of a supermassive black hole, thanks to an astronomical “double zoom” technique, made possible by a rare cosmic alignment. The black hole in question, called J1131 RX, is located about 6 billion light years from the earth and rotates more than half of the speed of light.

While the black hole itself remains hidden, it is devouring gas and nearby powders, which heat up to temperatures of millions of degrees generating a very powerful quasar. Recall that a quasar is the ultra-luminous nucleus of a galaxy fed by a supermassive black hole that swallows matter and transforms it into energy visible even to billions of light years. The crown of the black hole in question – a halo of overheated gases that surrounds the black hole – has an estimated size of about 50 astronomical units (AU), that is, roughly the diameter of our entire sun system, taking into account that an AU corresponds to about 150 million kilometers.

How was this “double zoom” possible? In the study it is explained that two gravitational lens mechanisms worked together to allow you to have this “double zoom” on the black hole. First of all, a front galaxy, i.e. a galaxy placed at about 4 billion light years from us, has acted as a strong gravitational lens (a gravitational lens is a cosmic object so massive as to bend the light that passes near it, creating distorted, multiple or enlarged images of celestial bodies in the background.

It is like a deforming mirror in space, foreseen by the general relativity of Einstein), curving and enlarged the light from Quasar. Then further “microlensing” (ie small gravitational lenses) were caused by individual stars present in that leading galaxy, which in turn opened from smaller and variable lenses, temporarily amplifying different portions of the crown. This caused independent flicit (variations in brightness) in the various “paintings” or pictures of the quasar formed by the main lens.

The study. Analyzing old data from the Alma Radio Telescope (Atacama Large Millimeter/Submillimeter Array) in Chile, collected on a scale of decades, the team noticed these variations which, initially, seemed strange: “This did not seem correct,” said the researcher Matus Rybak of the University of Leiden, who led the study.

A crucial test arrived with close observations (about a day later) in 2022: if the origin of the fluctuations had been close to the black hole, all the images should have changed brightness simultaneously.

Instead, the images varied independently, demonstrating that the prominent microlensing was influencing different parts of the crown.

Because it is important. It is the first direct measurement of the crown of a black hole on a scale so extensive, thanks to the “double zoom”. The observations showed that the issue in wavelengths in the millimeter is not static as expected, but it can also vary on stairs of days or less. This changes the previous ideas that considered such relatively stable emissions.

Understanding the crown and its variations is fundamental because it is connected to the magnetic fields around the black hole, which regulate both the entry of matter (that is, what the black hole “swallows”) and the expulsion of gas or jets. These processes determine how a black hole grows over time.

And the future? Unfortunately, one of the key telescopes for studying X-ray emission, Chandra X-Ray Observatory, is under threat of closing due to budget cuts. This would complicate the multiband observation (i.e. both radio/millimetric and x-ray) of these phenomena.

The team aims to collect new data not only from Alma but also by future telescopes such as the real Rubin Observatory, which will be able to discover many more gravitational lenses optically observable. These tools will allow you to study optical flicker (brightness fluctuations) with much higher precision.