This technical report discusses black holes and their properties. It defines a black hole as an area of space-time with such intense gravitational pull that nothing, not even light, can escape. The report describes how black holes are formed from massive stars undergoing supernovas and collapsing under their own gravity. It also discusses observational evidence of black holes through detections of their intense gravitational lensing, jets of particles and electromagnetic emissions. The report concludes that while debated, black holes provide the best explanation for various astronomical observations and their existence is supported by modern theories of physics and astronomy.

1. Subhadra Sundar Chakraborty (CSE/2015/043)
S. Tushar (CSE/2015/042)
Amar Kr. Gupta (CSE/2015/053)
Akhil Mishra (CSE/2015/060)
Akshay Mishra (CSE/2015/052)
The Supernova andThe Supernova and
Black HolesBlack Holes
HU481
Technical Report Writing & Language Laboratory

2. Black Holes: A TheoreticalBlack Holes: A Theoretical
DefinitionDefinition
 An area of space-timeAn area of space-time
with a gravitationalwith a gravitational
field so intense thatfield so intense that
it’s escape velocity isit’s escape velocity is
equal to or exceedsequal to or exceeds
the speed of light.the speed of light.
 The important thing isThe important thing is
that this area can be ofthat this area can be of
any size.any size.

3. The Finite Speed of LightThe Finite Speed of Light
 The base of physicalThe base of physical
theories assumes thattheories assumes that
speed of light inspeed of light in
vacuum is finite andvacuum is finite and
maximum possible.maximum possible.
(A black-hole-powered jet of(A black-hole-powered jet of
subatomic particles traveling atsubatomic particles traveling at
nearly the speed of light out of thenearly the speed of light out of the
M87 galaxy)M87 galaxy)

4. Escape Velocity, Density, andEscape Velocity, Density, and
Schwarzschild RadiusSchwarzschild Radius
 Every entity has anEvery entity has an
escape velocity asescape velocity as
 VVESCESC = sqrt(2GM / R)= sqrt(2GM / R)
 From thatFrom that
Schwarzschild RadiusSchwarzschild Radius
can be easily found.can be easily found.
 All comes down to aAll comes down to a
matter of density.matter of density.
√(2∗GM
R )

5. Thinking in Terms of GeneralThinking in Terms of General
RelativityRelativity
 Einstein’s Theory ofEinstein’s Theory of
General RelativityGeneral Relativity
basically says thatbasically says that
gravity warps spacegravity warps space
time.time.
 It can be depicted byIt can be depicted by
drawing an analogy todrawing an analogy to
bending rubberbending rubber
sheets.sheets.
The Bending of Space and
Time

6. Types of Black HolesTypes of Black Holes
 ““Normal Sized” BlackNormal Sized” Black
HolesHoles
 Microscopic (Primordial)Microscopic (Primordial)
SizedSized
 Super-Massive BlackSuper-Massive Black
Holes (On the order ofHoles (On the order of
millions to billions ofmillions to billions of
Solar Masses)Solar Masses)
 (Estimated 3 million solar(Estimated 3 million solar
masses for Milky Waymasses for Milky Way
Black Hole)Black Hole)

7. How Normal Black Holes ComeHow Normal Black Holes Come
AboutAbout
 Most Black Holes areMost Black Holes are
believed to comebelieved to come
about from the deathabout from the death
of massive stars.of massive stars.
 These deaths areThese deaths are
termed as Supernova.termed as Supernova.

8. Supernovas ExplainedSupernovas Explained
 After many fusion cycles, star’s core reduces to FeAfter many fusion cycles, star’s core reduces to Fe3+3+ (Iron)(Iron)
ion. If the star now is of mass M < 1.4 Mion. If the star now is of mass M < 1.4 Msunsun , the star will, the star will
degenerate as a Type II supernova. Otherwise, itdegenerate as a Type II supernova. Otherwise, it
becomes a white dwarf, supported by degeneratebecomes a white dwarf, supported by degenerate
electron pressure.electron pressure.
 This mass limit for supernovas is the Chandrasekhar limit.This mass limit for supernovas is the Chandrasekhar limit.

9. Black Hole or Neutron Star?Black Hole or Neutron Star?
 If the star the wentIf the star the went
supernova was betweensupernova was between
1.4 and 3 M1.4 and 3 Msunsun , then the, then the
remnant will be a Neutronremnant will be a Neutron
Star supported byStar supported by
degenerate neutrondegenerate neutron
pressure (Pulsar).pressure (Pulsar).
 Otherwise,Otherwise,
MMfinalfinal > 3M> 3Msunsun , and the result, and the result
is a black hole because theis a black hole because the
is no source of outwardis no source of outward
pressure strong enough.pressure strong enough.

10. Where Could Super-Massive BlackWhere Could Super-Massive Black
Holes Exist?Holes Exist?
 The only known placesThe only known places
in the Universe wherein the Universe where
there could be enoughthere could be enough
mass in one area is inmass in one area is in
the center of massivethe center of massive
galaxiesgalaxies
 Not believed to beNot believed to be
anywhere elseanywhere else

11. The Stellar Seed ModelThe Stellar Seed Model
 Provided that theProvided that the
surroundingsurrounding
environment isenvironment is
sufficiently rich insufficiently rich in
matter, a giant blackmatter, a giant black
hole could result in anhole could result in an
initial “stellar seed” ofinitial “stellar seed” of
10 M10 Msunsun producedproduced
during a supernova.during a supernova.

12. Optical JetsOptical Jets
 The magnetic fieldsThe magnetic fields
around the black holesaround the black holes
come from thecome from the
surrounding hot matters.surrounding hot matters.
 The jets are made by theThe jets are made by the
Magnetic field of theMagnetic field of the
matter before it goes inmatter before it goes in
the Black Hole.the Black Hole.
 They emit synchrotronThey emit synchrotron
radio signalsradio signals
Cygnus A

13. CannibalismCannibalism
 Apparently, Quasars areApparently, Quasars are
only active on order ofonly active on order of
100 million years100 million years
 A dead quasar could beA dead quasar could be
revived with a new sourcerevived with a new source
food—by collidingfood—by colliding
galaxiesgalaxies
 Proof—elliptical galaxiesProof—elliptical galaxies
have been found to behave been found to be
active in radioactive in radio
transmissions as well.transmissions as well. Collision Galaxies NGC
2207 & IC 2163

14. The Expanding UniverseThe Expanding Universe
 There exist anThere exist an
observationobservation
stating whereverstating wherever
a person look ata person look at
into theinto the
universe, heuniverse, he
would observewould observe
everythingeverything
moving away.moving away.
 Of course , this isOf course , this is
not possible in anot possible in a
finite geometry.finite geometry.

15. More on expansion...More on expansion...
The universe
now centered
on the blue and
red dots.

16. Even more...Even more...
The universe
now centered
somewhere
else.

17. Observations of Super MassiveObservations of Super Massive
Black HolesBlack Holes
 Radio observations atRadio observations at
various radiovarious radio
telescopestelescopes
 X-Ray observationsX-Ray observations
from the orbitalfrom the orbital
Chandra ObservatoryChandra Observatory
 Optical observationsOptical observations
from Hubble Spacefrom Hubble Space
TelescopeTelescope

18. Travelling Towards a Black HoleTravelling Towards a Black Hole
It shouldn’t come as a surprise that we would die ifIt shouldn’t come as a surprise that we would die if
we were to travel towards a black hole. But whatwe were to travel towards a black hole. But what
is interesting is what happens before that.is interesting is what happens before that.
How would a Black Hole appear to us?How would a Black Hole appear to us?
1. Light coming from behind is distorted1. Light coming from behind is distorted
2. Hence objects far behind it would appear as2. Hence objects far behind it would appear as
a ring.a ring.
3. This is known as Gravitational Lensing.3. This is known as Gravitational Lensing.

19. Photon SpherePhoton Sphere
1. The next interesting stop is1. The next interesting stop is
photon sphere.photon sphere.
2. At this point more than half2. At this point more than half
of our vision is in completeof our vision is in complete
darkness.darkness.
3. The light neither gets sucked in nor leaves the Black Hole.3. The light neither gets sucked in nor leaves the Black Hole.
4. In this region, Photon particles orbit the4. In this region, Photon particles orbit the Event Horizon.Event Horizon.
5. Seeing in this region, one can get his or her rear view.5. Seeing in this region, one can get his or her rear view.

20. The Observer’s ViewThe Observer’s View
1. A falling object would not1. A falling object would not
be sucked in suddenly.be sucked in suddenly.
Fall would gradually slowFall would gradually slow
down.down.
2. It continues till event2. It continues till event
horizon where light cannothorizon where light cannot
escape.escape.
3. Object falls towards3. Object falls towards
singularity until diminishing view of the Universe finallysingularity until diminishing view of the Universe finally
disappears and there’s complete darkness.disappears and there’s complete darkness.

21. SpaghettificationSpaghettification
1. Now this is where things
would start to hurt.
2. Gravitational pull across
space is greater.
3. So parts facing singularity
will be pulled more
strongly than those facing
away.
4. The difference is so
pronounced that our body
will be stretched. The
effect is so incredible that
the scientists call it
Spaghettification.

22. Fate of UniverseFate of Universe
 All Black Holes Evaporate over time due to HawkingAll Black Holes Evaporate over time due to Hawking
RadiationRadiation
 Eventually the Universe will have no matter in a cold darkEventually the Universe will have no matter in a cold dark
death and all there will be left is radiation.death and all there will be left is radiation.
 Estimated Evaporation Time:Estimated Evaporation Time:
1010-7-7 (M/M(M/Msunsun))33 YearsYears
On order of 10On order of 102020 yearsyears

23. PicturesPictures
NGC4261

24. ConclusionConclusion
Existence of black holes are highly debated. However,Existence of black holes are highly debated. However,
without them the universe doesn’t seem to make anywithout them the universe doesn’t seem to make any
sense.sense.
The facts provide strong evidences that they do exist allThe facts provide strong evidences that they do exist all
over the space.over the space.

25. BibliographyBibliography
https://en.wikipedia.org/wiki/Supermassive_black_holehttps://en.wikipedia.org/wiki/Supermassive_black_hole

The Metaphysics BlogThe Metaphysics Blog

NASA Think Tank.NASA Think Tank. “NASA Hubble Web Exploratorium”.“NASA Hubble Web Exploratorium”. Annual SpaceAnnual Space
Magazine 2002Magazine 2002

http://www.exploratorium.edu/origins/hubble/tools/center.htmlhttp://www.exploratorium.edu/origins/hubble/tools/center.html

Carroll, Sean M.Carroll, Sean M. Spacetime and Geometry.Spacetime and Geometry. Toronto. Pearson.Toronto. Pearson.
20072007

26. Thank You