July 18, 2022 (Nanowerk News) A team of international experts, known to disprove several discoveries of black holes, has found a black hole of stellar mass in the Large Magellanic Cloud, a galaxy adjacent to ours (Nature Astronomy , “An X- silent black hole born with an insignificant kick in a massive track of the Great Magellanic Cloud”). “For the first time, our team met to report on a discovery of a black hole, rather than rejecting one,” says study leader Tomer Shenar. In addition, they discovered that the star that gave rise to the black hole disappeared without any sign of a powerful explosion. The discovery was made thanks to six years of observations obtained with the Very Large Telescope (VLT) of the European Southern Observatory (ESO). “We have identified a‘ needle in a haystack ’,” says Shenar, who started the study at KU Leuven in Belgium and is now a Marie-Curie Fellow at the University of Amsterdam in the Netherlands. Although other candidates for similar black holes have been proposed, the team claims that this is the first “latent” stellar mass black hole to be detected unambiguously outside our galaxy. This artist’s print shows what the VFTS 243 binary system might look like if we looked at it closely. The system, located in the Tarantula Nebula in the Large Magellanic Cloud, is composed of a hot blue star with 25 times the mass of the Sun and a black hole, which is at least nine times the mass of the Sun. The sizes of the two binary components are not to scale: in fact, the blue star is about 200,000 times larger than the black hole. Note that the “slow” effect around the black hole is shown for illustrative purposes only, to make this dark object more noticeable in the image. The tilt of the system means that, looking at it from Earth, we cannot observe the black hole eclipsing the star. (Image: ESO / L. Road) Black holes of stellar mass are formed when massive stars reach the end of their life and collapse under their own gravity. In a binary system, a system of two stars rotating around each other, this process leaves behind a black hole in orbit with a luminous accompanying star. The black hole is “latent” if it does not emit high levels of X-ray radiation, which is how these black holes are normally detected. “It’s amazing that we hardly know about latent black holes, given how astronomers believe they are common,” explains co-author Pablo Marchant of KU Leuven. The newly found black hole has at least nine times the mass of our Sun and orbits a hot blue star that weighs 25 times the mass of the Sun. Latent black holes are especially difficult to detect because they do not interact much with their environment. “For more than two years, we have been looking for these black hole binary systems,” says co-author Julia Bodensteiner, an ESO researcher in Germany. “I was very excited when I learned about VFTS 243, which in my opinion is the most convincing candidate ever reported.” To find VFTS 243, the collaboration searched for nearly 1,000 massive stars in the region of the Magellanic Large Cloud Tarantula Nebula, looking for those that could have black holes as companions. Identifying these mates as black holes is extremely difficult, as there are so many alternative possibilities. “As a researcher who has denied possible black holes in recent years, I was extremely skeptical about this discovery,” says Shenar. Skepticism was shared by co-author Kareem El-Badry of the Center for Astrophysics Harvard and Smithsonian in the US, whom Shenar calls the “black hole destroyer.” “When Tomer asked me to review his findings, I had my doubts. But I couldn’t find a plausible explanation for the data not involving a black hole,” El-Badry explains. The discovery also allows the team a unique insight into the processes that accompany the formation of black holes. Astronomers believe that a black hole of stellar mass is formed when the core of a dying massive star sinks, but it is still unclear whether or not this is accompanied by a powerful supernova explosion. “The star that formed the black hole at VFTS 243 appears to have collapsed completely, with no sign of a previous explosion,” Shenar explains. “Evidence of this ‘direct collapse’ scenario has emerged recently, but our study certainly provides one of the most direct clues. This has huge implications for the origin of black hole fusions in the cosmos.” . The black hole in VFTS 243 was found using six years of observations of the Tarantula Nebula using the Large Fiber Multi-Element Spectrograph (FLAMES). Despite the nickname “black hole police”, the team actively encourages scrutiny and hopes that their work, published today in Nature Astronomy, will allow the discovery of other black holes of stellar mass orbiting massive stars. thousands of which are expected to exist in the Milky Way and the Magellanic Clouds. “Of course, I hope others in the field will carefully examine our analysis and try to work out alternative models,” El-Badry concludes. “It’s a very exciting project to participate in.”