A black hole is a region of space time exhibiting such strong gravitational effects that nothing, not even particles and electromagnetic radiation such as light can escape from inside it. The theory of general relativity predicts that a sufficiently compact mass can deform space time to form a black hole.
The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways a black hole acts like an ideal black body, as it reflects no light.
Moreover, quantum field theory in curved space time predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.
How are Black Holes identified?
As the universe is too big and dark, we can barely see the black holes because of the matching colors of both bodies. But scientists had found a way to spot a black hole by following the massive shadow cast by it in many heavenly bodies.
Event Horizon Telescope(EHT) Project
The Event Horizon Telescope is a project to create a large telescope array consisting of a global network of radio telescopes and combining data from several very-long-baseline interferometry stations around the Earth. The aim is to observe the immediate environment of the super massive black hole Sagittarius A* at the center of the Milky Way, as well as the even larger black hole in the center of the super giant elliptical galaxy Messier 87, with angular resolution comparable to the black hole’s event horizon.
It previously, on 10th April, 2019 was successful to capture the photo of a super massive Black Hole, located at the center of Messier 87 Galaxy, commonly known as M87. The Black Hole located there is about 6.5 Billion times massive than our Sun of solar system. The black hole was given the name Pōwehi, meaning “embellished dark source of unending creation” in Hawaiian.
Messier 87(M87) is a super giant elliptical galaxy in the constellation Virgo. One of the most massive galaxies in the local Universe. It has a large population of globular clusters about 12,000 compared with the 150–200 orbiting the Milky Way and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs (4,900 light-years), traveling at relativistic speed. It is one of the brightest radio sources in the sky, and a popular target for both amateur and professional astronomers.
The French astronomer Charles Messier discovered M87 in 1781, and cataloged it as a nebulous feature while searching for objects that would otherwise confuse comet hunters. M87 is located about 16.4 million parsecs (53 million light-years) from Earth and is the second-brightest galaxy within the northern Virgo Cluster, having many satellite galaxies. Unlike a disk-shaped spiral galaxy, M87 has no distinctive dust lanes. Instead, it has an almost featureless, ellipsoidal shape typical of most giant elliptical galaxies, diminishing in luminosity with distance from the center. Forming around one-sixth of its mass, M87’s stars have a nearly spherically symmetric distribution. Their population density decreases with increasing distance from the core. It has an active super massive black hole at its core, which forms the primary component of an active galactic nucleus. The black hole was imaged in 2017 by the Event Horizon Telescope, with a final, processed image released on 10 April 2019.
The galaxy is a strong source of multi wavelength radiation, particularly radio waves. Its galactic envelope extends to a radius of about 150 kilo-parsecs (490 thousand light-years), where it is truncated possibly by an encounter with another galaxy. Its interstellar medium consists of diffuse gas enriched by elements emitted from evolved stars.
Super Massive Black Hole
A super massive black hole is the largest type of black hole, containing a mass of the order of hundreds of thousands, to billions of times, the mass of the Sun. This is a class of astronomical objects that has undergone gravitational collapse, leaving behind a spheroidal region of space from which nothing can escape, not even light. Observational evidence indicates that all, or nearly all, massive galaxies contain a super massive black hole, located at the galaxy’s center. In the case of the Milky Way, the super massive black hole corresponds to the location of Sagittarius A* at the Galactic Core. Accretion of interstellar gas onto super massive black holes is the process responsible for powering quasars and other types of active galactic nuclei.
First Image of Black Hole
On 10th April, 2019, The first ever real image of black hole was captured. It was so tiny in the picture that the crew scientists had to zoom it till it was formed bigger. The Diameter of super massive Black Hole in was 0.000100 cm.
The first ever picture of black hole has now open a new era for astrophysicists.
But the exciting thing is that, The General Theory of Relativity, first proposed by renowned Physicist Albert Einstein, had passed the test again. The thing is that, before 100 years before, in 1915 AD, among billion brain, only 1 brain of Albert Einstein could imagine it. Therefore, the very old General Theory of Relativity passed the test of several scientists and is in practice today as well.
“Imagination is important than Knowledge. Knowledge is Limited. Imagination encircles the World. Imagination is the language of Soul.”
– Renowned Physicist Albert Einstein