GENERAL PROFICIENCY PRESENTATION ON

The Holy Grail of Astrophysics- Black Holes

Department of Electronics and Telecommunication EngineeringGirijananda Chowdhury Institute of Management and Technology

Azara Guwahati-781017(Assam)

Presented by-Names Roll No.

Akash Saha G-12/12

Chinmoy Adhikary G-12/104

Debashish Basyas G-12/115

Debjani Debnath G-12/118

INTRODUCTION• What is a Black Hole?

An area of space-time where-– space is curved around it completely– Great mass– Unimaginably dense – Inescapable gravity– Escape velocity > c– Not even light can escape

Structure of black holes:

Three types:– Stellar-mass: 3 to 20

times the mass of our sun – Supermassive: millions to

billions of times the mass of our Sun

– Mid-mass: In between stellar-mass and supermassive

Term “black hole” was introduced by John Wheeler in 1967.

Black hole classifications

Class Mass Size

Supermassive black hole

~105–1010 MSun

~0.001–400 AU

Intermediate-mass black hole

~103 MSun~103 km ≈

REarth

Stellar black hole ~10 MSun ~30 km

Micro black hole up to ~MMoon

up to ~0.1 mm

In the background: Simulation of a Supermassive Black hole

Characteristics

• Variety of masses and sizes, structures all alike.

• Entire mass concentrated in an almost infinitely small and dense point called a ‘singularity’.

• This point surrounded by the ‘event horizon’.

• It is surrounded by the ‘Ergosphere’- a region in which the black hole drags space itself.

In the background: M87 giant elliptical galaxy has a powerful jet, which is coming from the a disk around 109Msun black hole

Properties

• no-hair theorem- a black hole has only three independent physical properties: – Mass– Charge and– Angular momentum.

History • 18th century- John Michell and Pierre-Simon Laplace

first mention objects with a huge gravitation, from which even light cannot escape.

• 1915- Albert Einstein develops the theory of general relativity.

• 1916-Karl Schwarzschild finds black holes as a solution to Einstein’s equations

• 1939-Robert Oppenheimer and Hartland Snyder predict that massive stars can collapse into black holes

• 1967-Term “black hole” introduced by John Wheeler …

In the background: Merging galaxy Cen A

Formation

• when a giant star dies• blown into space as a

supernova explosion.• core collapses under its

own weight.• If remaining mass >

mass of 3 Suns, it will collapse into a black hole.

M15 - one globular cluster with a suspected black hole at its center.

When the stars reaches its end of life, gets crushed under its own gravity, leaving

behind a black hole• .

If black holes are black, how can we find them?

• three ways:1. Weird motion of

objects2. Gravitational lensing3. Accretion disc and

Relativistic jets

In the background: simulation of a gas cloud after close approach to the black hole at the center of the Milky way

How do black holes affect things near them?

• In danger of Being gobbled up by a black hole? No !

• Stellar-mass black holes don’t go around tearing up stars and eating everything in sight!

• Total mass the inner region of a galaxy ≈ the mass of its central black hole!

• A ‘Blast’ from the past , literally!

What happens when you fall into a black hole?

• “spaghettification.”• our math (and intuition)

fail us• At the singularity, space

and time as we know them come to an end.

Can black holes be used to travel through spacetime?

• Science fiction cliché- fact to be?• Can form a tunnel in space called a wormhole

What can we learn from black holes?

Ultimate endpoints of matter.Ripples in fabric of the UniverseLooking back all the way to Time Zerospace, time, and everything in between.

Where are black holes located?

To Infinity and Beyond

• EXIST-The Energetic X-ray Imaging SurveyTelescope (EXIST) is a proposed NASA satellite that will look at the energetic X-

rays emitted from black holes and other exotic astronomical objects

• one of the three “Einstein Probes” in NASA’s Beyond Einstein Program.

• next decade, with unparalleled sensitivity