Our Milky Way has a secret heart of darkness, shrouded in mystery and well hidden from our view. Within this strange region, resides a powerful gravitational beast: a supermassive black hole called Sagittarius A *–gold Sgr A * (pronounced saj-a-star) in short, it weighs millions of times more than our Sun. Sgr A * has kept its many secrets hidden from the prying eyes of curious astronomers, now it is finally beginning to tell its story, and what a story it is! In May 2018, astronomers using the Chandra X-ray Observatory, announced that they have discovered evidence of the existence of thousands of relatively small stellar mass black holes, performing an exotic ballet near the dark heart of our Galaxy, where Sgr A * dwells. Stellar mass black holes They typically weigh between 5 and 30 times the mass of the sun, and this newly discovered treasure filled with these “smaller” objects is three light-years from where Sgr A * it reigns in a secret and sinister splendor: a bewitching heart of darkness that keeps things to itself.

Three light years is a very short distance on cosmic scales. Theoretical studies of the dynamics of stars that inhabit galaxies have suggested that a significant population of stellar mass black holes–maybe up to 20,000– could wander inward as time goes on and finally reunite Sgr A *. This recent study using data obtained from Chandra provides the first observational evidence for the existence of such a group of bewitching black holes in the heart of our Milky Way.

Stellar mass objects are born as a result of the gravitational collapse of an especially massive star. This strange birth is usually announced by a brilliant display of heavenly fireworks called supernova. Supernovae They are the most powerful stellar explosions known, and they are so bright that they can often be observed to the very edge of the observable Universe, and can actually outshine their entire galactic host for a brief blink of an eye in cosmic. time scales. Stellar mass black holes are often called collapses.

FOR stellar mass dungeon, which is firmly locked in a close orbit with a star, will steal gas from its unfortunate companion. Astronomers call these systems X-ray binaries. The stolen stellar material falls into a disk It heats up to millions of degrees and emits X-rays before disappearing into the hungry jaws of the gravitational beast. Some of these X-ray binaries appear as point sources in the Chandra Photography.

therefore, the dungeon it is observable in X-rays. In contrast, astronomers can observe the victimized companion star using optical telescopes. The release of energy for both black holes and neutron stars they are of the same order of magnitude and, for this reason, astronomers often find it difficult to distinguish between the two objects.

Neutron stars are the very dense, city-sized remnants of a massive star that has perished in the blazing fireworks of a supernova explosion. Indeed, neutron stars are so dense that a teaspoonful of neutron starthings can weigh as much as a school of whales. However, the massive stars that are the progenitors of neutron stars they are not as massive as the stars that collapse to become stellar mass black holes.

The good news is that neutron stars it sports some identifying attributes. Neutron stars show differential rotation, and can have both a magnetic field and localized explosions, which is called thermonuclear bursts. Whenever astronomers observe these gossip properties, the compact object inhabiting the binary system reveals itself as a neutron star–preferable to stellar mass black hole.

The derived masses come from observations of compact X-ray sources combining optical data with X-ray data. All the neutron stars that have been identified so far show masses below 2.0 solar masses. None of the compact systems with masses greater than 2.0 solar masses, which have been observed, show the properties of a neutron star. Therefore, the combination of these properties makes it increasingly probable that the class of compact stars sports masses above 2.0 solar masses are actually stellar mass black holes.

Our galaxy is home to several stellar mass black hole candidates, who reside closer to Earth than Sgr A *. Most of these candidates are members of X-ray binary systems in which the compact member of the duo steals star material from his partner through the accretion disk.

Hairless

FOR dungeon– of any size – can be described as having only three properties. According to certain assumptions “hairless” theories, a dungeon It has three fundamental properties: mass, electric charge, and spin (angular momentum). Scientists generally believe that all black holes they are born in the wild with a twist. However, a definitive observation of this turn has not been recorded, at least not yet. The twist of a stellar mass black hole it is due to the conservation of the angular momentum of the massive parent star that produced it.

The gravitational collapse of a massive star is a natural process. It is inevitable that when a massive star finally reaches the end of that long stellar path, in which all its sources of stellar energy are depleted, it will collapse under the relentless pull of its own gravity and then shatter in fire. Grand finale of a supernova explosion. If the mass of the collapsed part of the parent star is below the limit of neutron degenerate matter (Tolman-Oppenheimer-Volkoff – TOV – limit), the end result is a compact star. The compact star can be a white dwarf or a neutron star–but May also be a still hypothetical stellar object called a quark star. However, if the progenitor star, which is in the process of collapsing, has a mass greater than the TOV limit, the intense pressure of your own gravity will go on and on and U.S until volume zero is reached and a new stellar mass black hole it is born around that point in space.

According to Albert Einstein Theory of general relativity (1915), a dungeon of any mass can exist in nature. The smaller the mass, the higher the density of matter must be to give rise to a dungeon. No known process can form a dungeon with a mass less than a few times the solar mass. Yes there are black holes so small, that they exist anywhere in the Universe, they are probably primordial black holes.

Over the past twenty years, astronomers have managed to gather enough evidence to support the idea that our Milky Way is home to a supermassive beast in his secret heart of darkness. There, hidden in the center of our galaxy, its dinner awaits: a crushed star, perhaps, or a doomed gas cloud. Because this mysterious object lurks relatively close to our own planet, it provides astronomers with valuable information about the fascinating, annoying, and puzzling way extreme gravity behaves. For this reason, Sgr A * also sheds a fascinating new light on General relativity. Because black holes they are so completely black that astronomers try to understand their exotic properties by observing the light emitted by the blazing, fiery gas that immediately surrounds them. (accretion disk).

The treasure of stellar-mass black holes

A team of astronomers, led by Dr. Charles Hailey of Columbia University in New York, used data derived from Chandra to hunt X-ray binaries that contain black holes residing near Sgr A *. The scientists studied the X-ray spectra (the amount of X-rays observed at different energies) from sources that reside within about 12 light-years of our Milky Way. supermassive dark heart.

The team then went on to select sources that displayed X-ray spectra similar to those of X-ray binaries which showed relatively large amounts of low-energy X-rays. Using this technique, the scientists were able to detect fourteen X-ray binaries located about three light years from Sgr A *. A duo of X-ray sources is believed to contain neutron stars. This probability is based on the detection of characteristics neutron star outbursts observed in previous studies. For this reason, the two sources were removed from the analysis.

Dr. Hailey and his team concluded that most of the remaining X-ray binaries probably contains stellar mass black holes. The amount of variability they have shown over the years is different from that predicted for X-ray binaries lodging neutron stars.

Only the brightest X-ray binaries containing black holes are detectable at the distance of the resident of our galaxy supermassive black hole It is from Earth. For this reason, the detections included in this investigation suggest that a considerably larger population of X-ray binaries (at least 300 to one thousand) host stellar mass black holes in the general neighborhood surrounding Sgr A *.

This population of black holes, who possesses a stellar companion close to Sgr A *, could shed new light on the mysterious formation of X-ray binaries as a result of narrow passages between stars and stellar mass black holes. This discovery could also help future gravitational wave studies. That is because knowing the number of black holes, lurking in the heart of a typical galaxy, can help astronomers better predict how many gravitational wave events may be associated with them. Gravitational waves they are ripples in the fabric of space-time itself, and they provide astronomers with a new way of studying the Universe.

An even larger population of stellar mass black holes, who are loners, without a companion star to call their own, they should also be dancing nearby Sgr A *. According to theoretical follow-up research by Dr. Aleksey Generozov (Columbia University) and his colleagues, there should be more than approximately 10,000 stellar mass black holes haunting the hidden dark heart of our Milky Way.

While Dr. Hailey and his colleagues favor the stellar mass black hole scenario of their findings, they do not rule out the possibility that up to 50% of the sources observed are actually from a population of millisecond pulsars. FOR Millisecond pulse is a newborn that turns rapidly and regularly neutron star, fresh from the funeral pyre of its parent star who perished in a brilliant supernova explosion. Millisecond pulsars they have very powerful magnetic fields.

An article describing these results appears in the April 5, 2018 issue of the magazine. Nature.

Tea Chandra X-ray Observatory is a space observatory launched by NASA on July 23, 1999.