physicists are now in the golden age of understanding black holes. Since 2015, researchers have been able to use the Laser Interferometer Gravitational Wave Observatory (LIGO) to obtain the signals generated by the merger of black holes, and telescopes such as the Event Horizon Telescope (EHT) have taken the first pictures of black hole shadows. 2020 is no exception. A series of exciting and unique discoveries have deepened our understanding of black holes.
Below, let us review the top ten black hole discoveries in 2020.
2020 Nobel Prize in Physics in recognition of black holes found
if to prove that 2020 was a year of outstanding research achievements of black holes, the highest achievement award in the field of science – the Nobel Prize, awarded in October of that year three to study these mysterious universe Astrophysics physicist. They are Roger Penrose of the University of Oxford in the United Kingdom, who won half of the Nobel Prize in Physics for “discovering that general relativity predicts the formation of black holes”, and Andrea Gates of UCLA and the University of Bonn in Germany and Max Reinhard Genzel of the Planck Institute for Cosmophysics-for “discovering a super dense object in the center of the galaxy” shared the other half of the Nobel Prize in Physics. Gates is the fourth woman to win the Nobel Prize in Physics so far. The other three women who won the award were Madame Curie (1903), Maria Goppert-Meyer (1963) and Donna Strickland (2018).
LIGO observed the largest black hole merger to date
LIGO and Virgo, another gravitational wave observatory in Europe, can observe black holes through gravitational waves. Gravitational waves are huge ripples in the space-time structure caused by the vibration of massive objects. The LIGO-Virgo Gravitational Wave Observatory has contributed many impressive discoveries. However, in May 2020, the LIGO-Virgo team announced that it had discovered the largest black hole collision observed so far. The masses of these two black holes are respectively 85 times the mass of the sun and 66 times the mass of the sun. They collided and merged into a black hole of 142 times the mass of the sun. In addition to breaking the original record, this discovery is also the first discovery within the so-called “forbidden zone” of intermediate-mass black holes. Although astronomers have observed small-mass black holes about the size of the sun and know that there are super-large black holes millions of times the mass of the sun in the centers of galaxies, no one has found evidence of the existence of this medium-mass black hole before. The exact formation of intermediate-mass black holes remains to be further explored by scientists.
Primordial black hole
very short time after the Big Bang, the universe was filled with hot turbulent radiation. In some areas, the energy is so dense that in theory, this part of the energy itself would collapse and form a black hole. Although physicists do not know whether these primordial black holes (PBH) exist, they are already imagining what changes would be brought about by the existence of primordial black holes. Several papers have shown that some black holes smaller than black holes formed by dying stars may constitute dark matter-a mysterious matter that produces gravitational influence in the universe. In the future, scientists will carry out more experiments to find primordial black holes to prove or refute the existence of these primordial black holes.
There may be a very massive black hole
What would happen if the supermassive black holes in the center of the galaxy were merged together and then divided into 11 black holes? A paper published in September 2020 discussed the possibility of this “extremely massive black hole” (SLAB). The mass of a very massive black hole can reach at least 1 trillion or more of the mass of the sun. The largest known black hole is the quasar TON 618, with a mass of approximately 66 billion times the mass of the sun. The mass of a very massive black hole will be more than 10 times that of TON 618. Some extremely massive black holes may have formed in the early universe, and they are another type of primordial black holes. This means that we may be able to find clues about them through the cosmic microwave background radiation. The cosmic microwave background radiation is the optical radiation left by the universe 380,000 years ago. In addition, if there are extremely massive black holes between the earth and distant stars, we can also find them through gravitational lensing. At present, although extremely massive black holes only exist at the hypothetical level, they have attracted more and more attention.
LIGO discovered that asymmetric black holes merged
. Most of the dual black hole systems detected by the LIGO-Virgo Gravitational Wave Observatory consist of two black holes of equal mass. But in April 2020, the team announced that they had observed the most asymmetric black hole merger. The two black holes merged around 2.4 billion light-years away, and their masses were 8 times the mass of the sun and 30 times the mass of the sun, respectively. Northwestern University gravitational wave scientist Christopher Berry wrote: “It’s like melting an ordinary Oreo biscuit into a super Oreo biscuit.” Previously, astronomers thought such accidents were very rare, and they didn’t work. A few years of gravitational wave equipment may not be able to observe these phenomena. However, the findings of the LIGO-Virgo team questioned the above assumptions and prompted researchers to consider the possibility of hierarchical merging. In this type of merger, one black hole collides with another, and then the remnants of the collision continue to merge with the third black hole.
Black holes “spaghetti” stars
When a supermassive celestial body falls within a certain distance of a black hole, its extreme gravity can pull the celestial body into thin strips. This process is vividly described as “spaghettiization”. Since most black holes are hidden behind a vague layer of gas and dust, spaghettiization is rarely observed. But in October 2020, astronomers at the European Southern Observatory used the Very Large Telescope (VLT) and New Technology Telescope (NTT) to successfully capture the process of a star being “spaghettiized” with unprecedented clarity. This event is labeled “AT 2019qiz” and will help researchers to better understand gravity in extreme environments.
The nearest black hole
who do not want to be too close to a black hole (ending refer to the “spaghetti” of). Fortunately, the cosmic Pac-Man observed in May and the other two companion stars orbiting it are keeping a safe astronomical distance from each other. This triple star system consisting of a black hole and two stars is called “HR 6819” and is located in the telescope constellation of the southern constellation, about 1,000 light-years away from the earth. The distance between the nearest black hole and the Earth is about 3,000 light-years, which is more than three times the new record. Astronomers did not directly observe the black hole itself, but inferred the existence of the black hole based on the wobble of the trajectories of the other two stars in the HR 6819 system under the influence of gravity. Astronomers in the southern hemisphere can observe the two stars in the HR 6819 system with the naked eye on a clear night. They are located in the southwest corner of the telescope constellation, near the junction of the constellation with Pavo and Temple.
The black hole may be a fuzzy ball
To form a black hole, matter and energy must first collapse into a tiny dot with infinite density. Since such an infinity is almost impossible in physics, theorists have been trying to figure out a solution to this bizarre result. Therefore, they proposed a string theory, trying to replace all particles and forces with subatomic and vibrating strings. According to this string theory, the black hole may be something more peculiar—a yarn-like fuzzy ball composed of basic strings. In October 2020, a study showed that if the atoms in a neutron star (a kind of stellar remnant that is not dense enough to form a black hole) are actually a string of strings, then compressing these strings together can form a fuzzy ball, which is The aforementioned basic yarn-like fuzzy ball, not a black hole. This novel idea is not yet perfect, but it may be a potential way to solve the problem of infinity.
The universe lurking danger of “naked” black hole
physicists believe that every black hole should have hidden in the so-called “event horizon” behind. Once within the boundary of the event horizon, no one can escape. However, since the concept of black holes was first proposed, researchers have been thinking about whether event horizons are absolutely necessary. Is it possible that there is a black hole with no event horizon, that is, a “naked” black hole? If it exists, a naked black hole will be very dangerous. Because the known laws of physics are completely inapplicable within the event horizon of a black hole, and a naked black hole does not even have this last protective barrier. Although most theorists believe that black holes cannot exist naked, a paper published in November suggests that there may be a way to confirm this conjecture. The trick is to find the difference in the accretion disk. The difference in the accretion disk can distinguish a naked black hole from a normal black hole.
Black hole treasure house
For scientists studying black holes, the Christmas surprise in 2020 comes very early. In October, the LIGO-Virgo gravitational wave observatory team released a brand new catalog containing dozens of gravitational wave signals observed between April and September 2019. These 39 events contained many interesting discoveries, such as the merger of two supermassive black holes and a 142 times solar mass black hole, an 8 times solar mass black hole, and a 30 times solar mass black hole. The merging brought about a rare extremely asymmetric merger. Events, and mysterious celestial bodies that look like both small-mass black holes and large neutron stars. The researchers were very pleasantly surprised by these data. These data indicate that the joint device can capture a new signal every 5 days on average. Researchers plan to use this data to better understand the behavior and frequency of black hole merging.
