black hole ,types of black hole, size,relativity theory of einstein, components of black hole. how somethings convert into black hole

1. Black Hole

2. Presented by

3. Black hole
• A black hole is an area of space with
a gravitational field so strong that
nothing, not even light, can escape
it.
• Black holes are volumes of space
where gravity is extreme enough to
prevent the escape of even the
fastest moving particles. Not even
light can break free, hence the name
‘black’ hole.

4. History
• Albert Einstein first predicted the existence of black holes in
1916, with his general theory of relativity. Albert Einstein was the
first to suggest that our universe contains such strange, dense,
massive objects. Black holes emerge from Einstein’s equations of
general relativity as a natural consequence of the death and
collapse of massive stars
• The term “black hole” was coined many years later in 1967 by
American astronomer John Wheeler. After decades of black holes
being known only as theoretical objects, the first physical black
hole ever discovered was spotted in 1971.

5. Cont.
• In 2006, Stephen Hawking proposed that microscopic
black holes are formed in the huge explosion that gave
birth to universes.
• In 2019 the Event Horizon Telescope (EHT) collaboration
released the first image ever recorded of a black hole.
• The image maps the sudden loss of photons (particles of
light). It also opens up a whole new area of research in
black holes, now that astronomers know what a black
hole looks like.

7. STRUCTURE OF BLACK HOLES:
• Singularity:
• The point where whole mass of a black hole is concentrated.
• Photon Sphere:
• The outer edge where light bends but is still escapable.
• Event Horizon:
• It is a “point of no return” around a black hole.
• Accretion Disk:
• It is a disk of gases, dust, stars and planets that fall into the orbit
of a black hole.

9. Schwarzschild radius
• The concept of a black hole can be
understood by thinking about how fast
something needs to move to escape the
gravity of another object – this is called the
escape velocity.
• The radius at which a mass has an escape
velocity equal to the speed of light is called
the Schwarzschild radius. Any object that is
smaller than its Schwarzschild radius is a
black hole – in other words, anything with
an escape velocity greater than the speed
of light is a black hole.

10. Cont.
• The Schwarzschild radius (Rg) of an object of mass M is
given by the following formula, in which G is the universal
gravitational constant and c is the speed of light:
• Rg = 2GM/c2
• Where G is universal gravitational constant and M is the
mass of object c is the speed of light
• The Schwarzschild radius is named for the German
astronomer and physicist Karl Schwarzschild, who
investigated the concept in the early 20th century.

11. General relativity

12. Gravity bend the path of light

13. How black holes form
• There are so many theories about formation
• The most obvious way of black hole – the core collapse of massive stars
at least with the size of three solar masses. M= 1.989 x 10^30 kg. When
the stars reaches its end of life, gets crushed under its own gravity,
leaving behind a black hole.
• When a gigantic star reaches the final stage of its life and is about to
go supernova, it spends all the nuclear fuel by then. So it stops burning
and heating up and cannot create the nuclear energy required to feed
the star.

15. RADIO JETS
• Quasar is a supermassive black hole that is
actively feeding on material. The infalling
matter has swirled into a disk that has heated
up, and it shines so brightly that its light
drowns out the rest of the galaxy around the
black hole.
• Scientists have spotted plasma jets — streams
of energy and hot matter — fleeing the core of
certain black holes at one-third the speed of
light. Researchers still aren’t certain how these
jets form or escape celestial voids.
• Interaction of jet materials with magnetic field
gives rise to Radio emission.

16. TYPES OF BLACK HOLES:
• Stellar-mass Black Holes:
• Stellar-mass black holes are created when massive stars
explode, leaving behind a black hole with the mass of just a
few suns.
• Supermassive Black Holes:
• Supermassive black holes exist in the hearts of galaxies and
usually contain the mass equivalent to millions and billions
of suns.
• Intermediate Black Holes:
• Such bodies could form when stars collide in a chain
reactions and usually contain the mass equivalent to
hundreds and thousands of suns.

17. The sizes of black holes
The diameter of a black hole’s
event horizon increases in
direct proportion to its mass. A
black hole with 10 times the
Sun’s mass would span 37 miles
(60 km), while the one in the
Milky Way’s center measures 17
Suns across.

18. HOW DO WE FIND BLACK HOLES:
• The X-rays are sent off into space and when they strike the matter
around the black hole , it can be detected.
• Binary X-ray sources are placed to find strong black hole .
• Another sign of the presence of a black hole is random variation
of emitted Xrays. And gravitational lensing , accretion disks and
gas jets .
• As the light emitted by distant galaxies passes by massive objects
in the universe, the gravitational pull from these objects can
distort or bend the light. This is called gravitational lensing.

20. FALLING INTO A BLACK HOLE
• A black hole is a place where the force of gravity is so powerful
that you would need to be travel at a speed faster than the speed
of light to escape its pull. Since nothing in the universe is faster
than the speed of light, nothing that falls into a black hole can
ever escape.
• The pulling force would increase as you moved toward the center,
creating what’s called a “tidal force” on your body.
• If you fell into a large enough black hole, no one outside would be
able to see you, but you’d have a view of them. Meanwhile, the
gravitational pull would bend the light weirdly and distort your
last moments of vision.

21. FAMOUS BLACK HOLES:
•Cygnus X-1
•Sagittarius A*
•M87
•Centaurus A

22. Thank you