It is monitored very closely by international teams of astronomers. This supermassive black hole is located at the heart of the galaxy 1ES 1927+654, approximately 270 million light years away, in the constellation Dragon, reports a NASA article.
In 2018, the black hole began to show unusual properties, notably with a major flare in visible light, ultraviolet and X-rays. Since then, Eileen Meyer has not let go of it. On January 13, this assistant professor at the University of Maryland Baltimore County (UMBC) was able to present the results of her team in the journal The Astrophysical Journal Letters. After a period of calm, the black hole became active again in 2023 with an increase in X-rays and has since attracted the interest of many other researchers around the world. Their discoveries attribute new behaviors to the black hole, such as a plasma jet, or even X-ray fluctuations.
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Plasma jets detected
Since 2023, this team of American researchers has intensively observed the black hole using several tools. In particular, they use a network of radio telescopes called the Very Long Baseline Array, which combines signals from different satellite dishes located throughout the country. This creates a kind of high-resolution camera that can detect features less than a light year away in the galaxy where the black hole is located.
Radio data collected in February, April and May 2024 reveal new details about its activity: jets of plasma, extending on either side of the axis of the black hole. Another observation concerns extremely rapid X-ray variations detected between July 2022 and March 2024.”During this period, the X-ray brightness steadily increased and decreased by 10% every few minutes. These changes (…) are difficult to detect around supermassive black holes and have only been observed in a few systems so far ” details NASA.
-The culprit: an orbiting object, probably a white dwarf
For the researchers, it then became a question of knowing what could have caused these fluctuations. “These oscillations can be produced by an object orbiting in the black hole's accretion disk” said Megan Masterson, a doctoral candidate at the Massachusetts Institute of Technology (MIT) in Cambridge.
Orbiting masses generate ripples in space-time called gravitational waves. These waves drain orbital energy, bringing the object closer to the black hole, increasing its speed and shortening its orbital period.
But then why didn't he fall into the black hole? According to the researchers, this is explained by an intriguing phenomenon: “We realized that as the object got closer to the black hole, the hole's strong gravitational pull could begin to pull material away from the object. This loss of mass could compensate for the energy removed by gravitational waves, thus stopping the movement of the object towards the interior of the black hole” explains Megan Masterson.
Several hypotheses were then suggested about the nature of this object. According to astronomers' predictions, it could be a low-mass white dwarf, born from the residue of a star, and approximately the size of Earth. If so, the gravitational waves it produces will be detectable by LISA (Laser Interferometer Space Antenna), a European Space Agency (ESA) mission in partnership with NASA, which is expected to be launched in the next decade .
