INTRODUCTION ABOUT BLACK HOLES

1. BLACK HOLES

2.  INTRODUCTION
 FORMATION OF BLACK HOLES
 PARTS OF BLACK HOLES
 TYPES OF BLACK HOLES
 THEORIES
 FACTS

4. What is a Black Hole?
In Newtonian gravity, the escape velocity from a
spherical body depends on its size and mass. As the
size decreases and the mass increases, escape velocity
goes up. For the escape velocity to equal the speed of
light (186,000 miles (299,000 km) per second), nature
requires a certain size for a given mass. If an object
contracts to this critical size, light can no longer escape
from its surface to the distant universe.
This is the essence of a black hole.

5. A black hole is a region of spacetime exhibiting such strong
gravitational effects that nothing—not even
particles and electromagnetic radiation such as light—can
escape from inside it.

6. The first use of the term "black hole" in print was by science
journalist Ann Ewing in her article "'Black Holes‘ in Space",
dated 18 January 1964, which was a report on a meeting of
the American Association for the Advancement of Science
held in Cleveland, Ohio.
In December 1967, a student reportedly suggested the
phrase "black hole" at a lecture by John Wheeler; Wheeler
adopted the term for its brevity and "advertising value", and
it quickly caught on, leading some to credit Wheeler with
coining the phrase.

11.  If the star the went
supernova was between
1.4 and 3 Msun , then the
remnant will be a
Neutron Star supported
by degenerate neutron
pressure (Pulsar).
 Otherwise,
Mfinal > 3Msun , and the
result is a black hole
because the is no source
of outward pressure
strong enough.

14.  The only known
places in the
Universe where
there could be
enough mass in
one area is in the
center of massive
galaxies
 Not believed to be
anywhere else

15.  From “Lumps” in
the early universe
 The “Stellar Seed”
Model
 Collapse of a whole
star cluster

16.  In the “Big Bang” the
whole universe was in a
really dense state. So
much that perhaps
lumps could have
formed and of matter
dense enough that a
black hole was formed.
 There was enough
surrounding matter that
galaxies formed around
the lumps
 Could explain why
pockets of interstellar
gas never became
galaxies

17.  Provided that the
surrounding
environment is
sufficiently rich in
matter, a giant
black hole could
result in an initial
“stellar seed” of 10
Msun produced
during a supernova.

18.  If the stars of a tight
knit cluster of the
moderately young
Universe had all
relatively the same size
stars (above the
Chandrasekhar Limit),
there would be quite a
few Black Holes
forming
simultaneously causing
smaller stars to be
absorbed, and black
holes to combine.
 NGC 1850 to the right

19.  Radio observations
at various radio
telescopes
 X-ray observations
from the orbital
Chandra
Observatory
 Optical
Observations from
Hubble Space
Telescope

20. NGC4261

27. This ring like structure is called as
photon sphere.

29.  In terms of
gravitational force,
every object has an
escape velocity as
 vesc = Sqrt[(2 G
M)/r].
 From that
Schwarzschild
Radius can be easily
found.
 All comes down to
a matter of density.

30.  Einstein’s Theory of
General Relativity
basically says that
gravity warps space
time.
 Rubber Sheet
analogue
 Down, up, and through the funnel. An
embedding diagram is generally a good
representation of a black hole's warping
of nearby space-time. But such 2-
dimensional illustrations can also cause
conceptual problems.

31.  The black hole no
hair theorem shows
that mass, charge,
and angular
momentum are the
only properties a
black hole can
possess

45.  All Black Holes Evaporate over time due to
Hawking Radiation
 Eventually the Universe will have no matter in
a cold dark death and all there will be left is
radiation.
 Evaporation Time:
1 * 10^-7 (M/Msun)^3 Years
On order of 1* 10^20 years