Nature

Black Hole sceptics discover a stellar-mass black hole

2022-07-18

This composite image shows the star-forming region 30. Doradus, also known as the Tarantula Nebula. The background image, taken in the infrared, is itself a composite: it was captured by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) and the Visible and Infrared Survey Telescope for Astronomy (VISTA), shows bright stars and light, pinkish clouds of hot gas. The bright red-yellow streaks that have been superimposed on the image come from radio observations taken by the Atacama Large Millimeter/submillimeter Array (ALMA), revealing regions of cold, dense gas which have the potential to collapse and form stars. The unique web-like structure of the gas clouds led astronomers to the nebula’s spidery nickname. ESO, ALMA (ESO/NAOJ/NRAO)/Wong et al., ESO/M.-R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit

Composite infrared and radio image of 30 Doradus — This composite image shows the star-forming region 30. Doradus, also known as the Tarantula Nebula. The background image, taken in the infrared, is itself a composite: it was captured by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) and the Visible and Infrared Survey Telescope for Astronomy (VISTA), shows bright stars and light, pinkish clouds of hot gas. The bright red-yellow streaks that have been superimposed on the image come from radio observations taken by the Atacama Large Millimeter/submillimeter Array (ALMA), revealing regions of cold, dense gas which have the potential to collapse and form stars. The unique web-like structure of the gas clouds led astronomers to the nebula’s spidery nickname. ESO, ALMA (ESO/NAOJ/NRAO)/Wong et al., ESO/M.-R. Cioni/VISTA Magellanic Cloud survey. Acknowledgment: Cambridge Astronomical Survey Unit

In what may be called a cosmic irony, a group of black hole debunkers found a black hole in our neighbouring galaxy, in a Large Magellanic Cloud. According to the study’s leader, Tomer Shenar, the team discovered a star that formed the black hole and disappeared without leaving any trace of a massive explosion.

The finding was made possible after six years of observations with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument of the Very Large Telescope (VLT) of the European Southern Observatory (ESO).

We found a “needle in a haystack,” said Shenar, a Marie-Curie Fellow at Amsterdam University in the Netherlands who began the study at KU Leuven in Belgium.

According to the research team, this is the first ‘dormant’ stellar-mass black hole to be unmistakably discovered beyond our galaxy, despite numerous hypotheses for such black holes having been suggested.

When giant stars near the end of their life and collide with one another due to gravity, stellar-mass black holes are created. If the black hole doesn’t generate a lot of X-ray radiation, which is how such black holes are normally found, it is considered “dormant.”

Given how prevalent astronomers think inactive black holes to be, co-author Pablo Marchant of KU Leuven says it is remarkable that we hardly know of any. The newly discovered black hole circles a bright, blue star that is 25 times the mass of our Sun and is at least nine times as massive.

Black holes that are dormant are particularly difficult to locate since they do not interact with their environment very much. According to co-author Julia Bodensteiner, a research fellow at the German ESO, they have been seeking such black-hole-binary systems for more than two years already. “I was excited”, she says, to learn about VFTS 243, which is, in her opinion, the strongest prospect yet.

Nearly 1000 massive stars in the Tarantula Nebula area of the Large Magellanic Cloud were combed by the collaboration in search of potential black hole partners in order to locate VFTS 243. It is quite challenging to determine whether these companions are black holes because so many other possible explanations exist.

“I was very sceptical” about this discovery, says Shenar, a physicist who has disproved the existence of black holes. Kareem El-Badry, the co-author and the man Shenar refers to as the “black hole destroyer” of the Center for Astrophysics | Harvard & Smithsonian in the United States, expressed the same doubt. “I had my doubts,” said Wl-Badry when Tomer requested him to confirm the results. However, “I could not” come up with a reasonable explanation for the data that did not include a black hole, says El-Badry.

The discovery also gives the scientists a novel perspective on the procedures that go along with black hole development. There is some debate about whether or not a strong supernova explosion occurs when the centre of a dying big star collapses, creating a stellar-mass black hole.