Topic : Black Hole and Its Types | All about black holes
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A black hole is a curve in spacetime fabric where gravity is so strong ,from which nothing can escape ,not even light or any Particles.
The idea of an object in space so massive and dense that light could not escape it has been around for centuries. Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity. which showed that when a massive star dies, it leaves behind a small, dense remnant core ,Which Later turn into a black hole. The term “black hole” was coined several years later in 1967 by American astronomer John Wheeler.
The theory of general relativity predicts that a sufficiently compact mass can distort spacetime to form a black hole. The boundary of the region from which no migration is possible is called the event horizon. Although the event horizon has a great influence on the fate and conditions of crossing an object, according to general relativity it has no locally detectable features.
In many ways, a black hole acts like an ideal black body, because it does not reflect light. Furthermore, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with a black body of the same spectrum with the same spectrum inversely proportional to its mass. This temperature is on the order of billions of Kelvin for a black hole of stellar mass, making it essentially impossible to observe.
The Schwarzschild radius is the radius of the event horizon around a non-rotating black hole. Any physical object, which has a radius smaller than the Schwarzschild radius, will be a black hole.
If you could compress the object down to a radius of its Schwarzschild radius, it would become a black hole.
- Types of Black holes:
In our known universe, astronomers have identified three types of black holes:
1) Supermassive black holes
2) stellar Black holes
3) Intermediate black holes.
But there is another type of black holes they are called Miniature Black holes, Actually they are hypothetical Black holes Predicted by Stephen Hawking.
Supermassive black holes
Supermassive black holes are the largest type of black hole, with masses ranging from hundreds to thousands-billions of the mass of the Sun .A black hole is a celestial object that undergoes the fall of gravity Which causes a Curves in Space time Fabric. Observational evidence and researches Scientists suggests that almost all large galaxies have a supermassive black hole, which is at the center of the galaxy. In the case of our Milky Way Galaxy, the supermassive black hole corresponds to the location of Sagittarius A in the galactic core.
Stellar black hole
A stellar black hole is a black hole formed by the collapse of gravity of a star. They have solar masses that range from about 5 to several tens. This process is seen as a hypernova explosion or gamma ray burst. These black holes are also known as callopers.
Intermediate Black hole
A black hole with a mass of 110-105 Sun Mass much larger than the stellar black hole but less than a supermassive black hole with 105-110 Sun Mass. Several Intermediate Black holes candidate objects have been discovered in our gas and many other nearby ones, based on the discrete spectra observations of indirect gas cloud velocity and accretion of different disclaimer strength.
Miniature Black hole
Miniature Black holes are hypothetical tiny black holes or we can say they are Quantum black holes ,In 1971 Stephen Hawking was the First Person to give the concept that Miniature black holes may exist.
Event horizon is defined as a boundary in the region of space around a black hole from which nothing can escape. If you are thinking light can escape , then you are wrong ,even light can’t escape it. To escape the event horizon of a black hole a object must have its escape velocity greater than speed of light.
Singularity of a black hole
In a simple word we can say Singularity is a infinitely small space with a huge mass , where density and gravity become infinite and space-time curves infinitely, and where the laws of Physics almost break down. Singularity is commonly known as Gravitational singularity and it is present in the center of a black hole.
People think that in Singularity things become infinite but in reality. Singularity is a place where general relativity breaks down.
As predicted by general relativity, the presence of a mass deformation occurs spacetime in such a way that the pathways taken by the particles are inclined towards the mass. At the event horizon of a black hole, this distortion becomes so strong that there are no routes leading away from the black hole.
Evaporation of a Black hole
In 1974, Hawking predicted that black holes are not entirely black but emit small amounts of thermal radiation at a certain temperature. This effect of thermal radiation has become known as Hawking radiation. With the help of Quantum field theory, he determined that a black hole should emit particles that display a perfect black body spectrum.
After Hawking’s many other Scientists verified the same thing. If Hawking’s theory on black hole radiation is correct, then black holes are expected to shrink and evaporate over time as they lose mass by the emission of photons and other particles.
As per research on this theory Scientists identified that , Large black holes emit less radiation than small black holes. If a black hole is very small, the effects of the radiation are expected to become very strong.
Entropy of a black hole:
The amount of entropy that must be assigned to a black hole in order for it to comply with the laws of thermodynamics is called black hole’s entropy. This is especially true for the first and second laws. Black hole entropy is a concept with geometric roots but with many physical consequences. It combines assumptions from gravity, thermodynamics and quantum theory together, and is thus considered as the yet hidden world of quantum gravity.
Real image of black hole
After many year of hard work and struggle ,On April 10, 2019, Scientists and researchers unveiled the first image of black hole(Supermassive black hole) in a conference. This task was not very easy, for this many researchers from different places worked together for this in a multi international collaboration.
Scientists have obtained the first image of a black hole using the Event Horizon Telescope observations at the center of the galaxy M87.In this image we can clearly see the luminous ring, which bends around a black hole in intense gravity as light, which is 6.5 billion times more massive than the Sun.
What happen when two black holes collide ?
In the past centuries people believe was No such events like colliding of two black holes occur , But after many years of observation and the data collected with the help of telescopes ,now we know that when two black holes collide it produces gravitational waves in the fabric of space-time. After the collision of black hole , the wave reaches the highest point. And then they become a large massive black hole.
So this is all about Black hole we have learnt many important things through this Article. I hope you enjoyed reading this , and that’s it for today , see you in the next article.