A “sleeping” black hole discovered for the first time outside our galaxy

It was estimated that many stellar black holes must exist in pairs with a star, but without tearing material from it and therefore could not signal themselves by shining in the form of X-rays after the accretion of this material. A candidate for such a “sleeping” black hole has just been discovered in the Large Magellanic Cloud by combining the method of radial velocities and that of gravitational microlensing.

Black holes have become commonplace in the media landscape in recent years, and despite the mysteries that still surround them, which touch on very deep questions of theoretical physics, they are commonly considered in astrophysics and science. cosmologycosmology. We even study theirs emissionsemissions ofgravitational wavesgravitational waves in conflict with others starsstars relativistic compressions. More recently, their surroundings have even been photographed with radio telescopes, revealing the existence of what is believed to be an event horizon, which is the very definition of a black hole when it is a closed surface. .

Admittedly, the final proof of the existence of black holes still eludes us, but doubts about their presence in certain corners of The Milky WayThe Milky Way and galaxiesgalaxies increasingly difficult to justify. What contrastcontrast with the early 1960s only a handful of visionaries, such as John Wheeler, taking these solutions from equationsequations of general relativitygeneral relativity seriously even EinsteinEinstein did not do.

The first contenders for the title of black holes were nonetheless flushed out during the 1970s, in the form of a binary systembinary system where a star-sized hole, i.e. produced bycollapsecollapse the gravity of a starstar probably at least 30 plentyplenty solar rays, also happened to be a strong source of X-rays upon accretion fabricfabric from its companion star.

This matter, as it spirals towards the black hole, actually forms a compact disk where viscous frictional forces between the spirals of gasgas adjacent rooms emit heatheat to the point of producing a bright hot plasma in the X-ray region.

Black holes are among the most opaque objects in the universe. Fortunately, however, they are among the most attractive, and it is by their exaggerated attractiveness that we can discover them. Giant black holes are the most monstrous ogres in the cosmic zoo, but they are not weapons of mass destruction. The jets of matter they produce would have helped ignite the first stars and form the first galaxies. Hubert Reeves and Jean-Pierre Luminet, specialists in modern cosmology, answer all your questions. To find out more, visit From Big Bang to Life. © ECP Group, YouTube

However, we know that the majority of stars form binary systems, so we must expect that there is a certain number of these binary Xbinary X in the Milky Way. However, it is also possible that the distance between a star-sized hole and its companion star is such that no appreciable transfer of matter occurs. So no discgrowthgrowth and no X-ray emission, for example because the star has not yet become one red giantred giant which has expanded to the point where it overflows what is called its Roche lobe, named after the mathematician and astronomerastronomer 19th century Frenche century.

The first emergent tip of a population of dormant black holes

This kind of stellar black hole is said to be ” sleepingsleeping and so far none had been discovered. That just changed thanks to an international team of astronomers who used the Flames instrument for their discovery (Fiber Large Array Multi Element Spectrograph) on it VLTVLT of’ESOESOas the researchers explain in an article published in Natural astronomy.

To do this they had to turn their gaze from VLT towards fogfog of the Tarantula situated in Large Magellanic CloudLarge Magellanic Cloud, a neighboring galaxy to our own. Six years of observations were necessary for the team led by Tomer Shenar, who began this research at KU Leuven in Belgium and is now a Marie-Curie Fellow at the University of Amsterdam, in the Netherlands.

The dormant black hole candidate has been dubbed VFTS 243. It contains at least nine times the mass of our SunSun and orbits a hot blue star weighing 25 times the mass of the Sun. Remarkably, it is not accompanied by noticeable traces of debris from an explosion supernovasupernova (More precisely I’orbitorbit quasi-circular and kinematics of VFTS 243 imply that the collapse of the progenitor star into a the black hole was associated with little or no ejected matter) suggests that, as thought, a gravitationally collapsing star can sometimes directly become a black hole without going through the supernova stage.

The star that formed VFTS 243’s black hole appears to have completely collapsed with no evidence of a previous explosionexplains Tomer Shenar in an ESO statement, adding, evidence for this “direct collapse” scenario has emerged recently, but our study arguably provides one of the most direct indications. This has enormous implications for the origin of mergersmergers black holes in the cosmos. »


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