The black hole in distant galaxy stuns scientists with prolonged flare
Astronomers from around the world witnessed an extraordinary phenomenon in the centre of a distant galaxy. It was the first event of its kind to be observed in the history of astronomy.
In 2019, a galaxy designated SDSS1335+0728, which had not stood out and was located 290 million kilometres from our planet, suddenly brightened. This unexpected flare drew the attention of scientists, who began to intensely observe the phenomenon using various instruments, both space-based and ground-based. Among them was the Very Large Telescope (VLT), part of the European Southern Observatory (ESO) in Chile.
A distant black hole surprised scientists
Professor Paula Sánchez Sáez from ESO describes the phenomenon as follows: "Imagine you’ve been observing a distant galaxy for years, and it always seemed calm and inactive. Suddenly, its [core] starts showing dramatic changes in brightness, unlike any typical events we've seen before."
The galaxy's brightening could be caused by various phenomena, such as a supernova explosion or the so-called tidal disruptions, which occur when a black hole rips apart a star approaching it. However, these flares usually last only a few tens to a maximum of a few hundred days. In the case of galaxy SDSS1335+0728, the flare has continued for over four years since the first changes were noticed.
Furthermore, this flare's characteristics differ from anything observed so far. After a thorough analysis of data collected from various instruments, scientists noticed that the galaxy emits much more ultraviolet, visible, and infrared light following the flare. In February of this year, it also began to emit X-rays.
"It's changing, in particular its energetic state" stated Prof. Sánchez Sáez.
Scientists believe that the most likely explanation is a flare in the core of the galaxy, where a supermassive black hole is located, similar to the centre of our galaxy, the Milky Way.
"If so, this would be the first time that we see the activation of a massive black hole in real time," emphasized co-author of the discovery Lorena Hernández García.
According to scientists, the black hole at the centre of the observed galaxy began rapidly consuming the surrounding gas. Supermassive black holes are located in the centres of most galaxies, including our Milky Way. Therefore, a similar phenomenon could also occur in the supermassive black hole of our galaxy (Sagittarius A*), although the probability of such an event is unknown.
Astronomers worldwide continue to observe the galaxy SDSS1335+0728, trying to understand what caused its flare. There is a chance that the changes they observe might be explained differently – for example, by a prolonged tidal disruption or some utterly unknown phenomenon. "Regardless of the nature of the variations, (this galaxy) provides valuable information on how black holes grow and evolve," Prof. Sánchez Sáez points out.
"We expect that instruments like (MUSE on the VLT or those on the upcoming Extremely Large Telescope) will be key in understanding (why the galaxy is brightening)," added the professor.
