A group of black holes in the secret heart of our galaxy
Our galaxy, the Milky Way, has a secret heart of darkness, shrouded in mystery and well hidden from view. Within this strange region resides a powerful gravitational beast, a super massive black hole called Sagittarius A*–Prayed Sgr A* (pronounced saj-a-star) for short, weighing millions of times more than our Sun. Although 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! As of May 2018, astronomers using NASA Chandra X-ray Observatoryannounced that they have discovered evidence of the existence of thousands of relatively small stellar mass black holesperforming an exotic ballet near the dark heart of our Galaxy, where Sgr A* Blackberry stellar mass black holes typically weighs between 5 and 30 times the mass of the Sun, and this newly discovered treasure trove full of these “smaller” objects is within three light-years of where Sgr A* reigns in secret, 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–perhaps as many as 20,000– could wander inward as time goes on, eventually gathering around Sgr A*. This recent study using data obtained from Chandra provides the first observational evidence for the existence of such a group of spell casters 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 heralded by a brilliant display of celestial fireworks called supernova. supernovae they are the most powerful stellar explosions known, and are so bright that they can often be seen to the very edge of the observable Universe, and can actually outshine their entire galactic host by a brief blink of an eye on time scales. cosmic. stellar mass black holes are often called collapsing
HAS stellar mass dungeon, which is tightly locked in a close orbit with a star, will steal gas from its unlucky partner. Astronomers call these systems x-ray binaries. The stolen star material falls into a disk which 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 image.
Therefore, the dungeon it is observable in X-rays. By contrast, astronomers can observe the victim companion star using optical telescopes. The release of energy for both black holes Y neutron stars they are of the same order of magnitude and, for this reason, astronomers frequently find it difficult to distinguish between the two objects.
neutron stars it is the very dense, city-sized remains of a massive star that has perished in the blazing fireworks of a supernova burst. Indeed, neutron stars are so dense that a full teaspoon of neutron star-things 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 They show some identifying attributes. neutron stars show differential rotation, and can possess both a magnetic field and localized explosions, called thermonuclear bursts. Every time astronomers observe these gossipy properties, the compact object that inhabits the binary system is revealed to be a neutron star–preferable to stellar-mass black hole.
The derived masses come from observations of compact x-ray sources that combines 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 likely that the class of compact stars sports masses above 2.0 solar masses are truly stellar-mass black holes.
Our Galaxy hosts several stellar mass black hole candidates, who reside closer to Earth than Sgr A*. Most of these candidates are members of binary x-ray systems in which the compact member of the duo steals stellar material from his partner through the accretion disk.
hairless
HAS dungeon–of any size–can be described as having only three properties. according to certain so-called “hairless” theories has dungeon it has three fundamental properties: mass, electric charge, and spin (angular momentum). Scientists generally believe that all black holes they are born in nature with a twist. However, no definitive observation of this spin has been recorded, at least not yet. The turn of a stellar mass black hole it is due to the conservation of 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, where all its stellar energy sources are exhausted, it will collapse under the relentless pull of its own gravity and then shatter. the fiery Grand finale of a supernova explosion. If the mass of the collapsed portion of the parent star is below the limit for neutron degenerate matter (Tolman-Oppenheimer-Volkoff–TOV–limit), the end result is a compact star. The compact star can be a white dwarf gold has neutron star–but May also be a still hypothetical stellar object called quark star However, if the parent star, which is in the process of collapsing, has a mass greater than the TOV limitthe intense grip of its own gravity will go on and on and us until zero volume is reached and a new stellar mass black hole is born around that point in space.
According to Albert Einstein General Relativity Theory (1915), has dungeon of any mass can exist in nature. The smaller the mass, the higher the density of the matter must be for a reaction to occur. dungeon. No known process can form a dungeon with a mass less than a few times the solar mass. Yes there are black holes that small, existing anywhere in the Universe, are probably primordial black holes.
Over the past twenty years, astronomers have been able to collect enough evidence to support the idea that our Milky Way galaxy does indeed host a super massive beast in his secret heart of darkness. There, hidden in the center of our galaxy, he awaits his dinner: a crushed star, perhaps, or a cloud of doomed gas. Because this mystery object lurks relatively close to our own planet, it provides astronomers with valuable insights into the fascinating, vexing, and puzzling ways extreme gravity behaves. For this reason, Sgr A* also sheds 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 dazzling, scorching gas that immediately surrounds them (accretion disk).
Treasure trove 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 contains black holes residing near Sgr A*. Scientists studied X-ray spectra (the number of X-rays observed at different energies) from sources that reside within about 12 light-years of our Milky Way. super massive 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, scientists were able to detect fourteen x-ray binaries located within about three light-years of Sgr A*. A duo of the X-ray sources are believed to contain neutron stars This probability is based on the detection of features neutron star outbursts observed in earlier 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 contain stellar-mass black holes. The amount of variability they have shown over the years is different from that predicted for x-ray binaries accommodation neutron stars
only the brightest x-ray binaries containing black holes are detectable at the distance of the resident of our galaxy super massive black hole it’s from Earth. For this reason, the detections included in this research suggest that a considerably larger population of undetected, weaker x-ray binaries (at least 300 up to a thousand) host stellar mass black holes in the general surrounding neighborhood Sgr A*.
This population of black holeshave a close stellar companion Sgr A*, could shed new light on the mysterious formation of x-ray binaries resulting from close passages between stars and stellar-mass black holes. This discovery could also help future studies of gravitational waves. This is because knowing the number of black holeslurking 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 holeswho are lonely, without a companion star to call their own, should be dancing nearby too Sgr A*. According to follow-up theoretical research by Dr. Aleksey Generozov (Columbia University) and colleagues, there should be more than about 10,000 stellar mass black holes lurking in the dark hidden heart of our Milky Way.
While Dr. Hailey and colleagues are in favor of stellar mass black hole scenario for their findings, they do not rule out the possibility that up to 50% of the observed sources are actually from a population of millisecond pulsar. HAS millisecond pulsar is a newborn who spins quickly and regularly neutron starfresh from the funeral pyre of its parent star that 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 journal. Nature.
Tea Chandra X-ray Observatory It is a space observatory launched by NASA on July 23, 1999.
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