Title Page Janet Moore NASA Educator Ambassador. What is a Black Hole? Definition: a place where the escape velocity is faster than the speed of light.

Title PageTitle Page

Janet Moore

NASA Educator Ambassador

What is a Black Hole?What is a Black Hole?

Definition: a place where the escape velocity is faster than the speed of light.

Close-up Picture of a Black HoleClose-up Picture of a Black Hole

Escape VelocityEscape Velocity

Definition: the velocity at which something must travel

away from an object such that the gravity

of the object cannot stop it.

Escape Velocity (2)Escape Velocity (2)

Escape velocity depends on the

gravitygravityof the object

Escape Velocity (3)Escape Velocity (3)

Lowmass

Mediummass

Highmass

Very high mass

for a given radius

^

Escape Velocity (4)Escape Velocity (4)radius decreases increases

What is a Black Hole?What is a Black Hole?

It’s an object of high enough It’s an object of high enough mass mass

and small enough radius and small enough radius such that such that

the escape velocity is the escape velocity is faster than light.faster than light.

Nothing can escape.

Or, put another way …Or, put another way …

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The First Way A Black The First Way A Black Hole Can Kill YouHole Can Kill You

1.2.3.4.5.6.7.

Falling in

Down the DrainDown the Drain

Forcing the IssueForcing the IssueThe force of gravity from an object depends on

1) the mass of the object2) your distance from it

Black holes are really massive, And you can get

really, really close

But this means….

Gm1m2

F=

r2

So if it’s really massive, or you’re really close, the force is high.

Forcing the Issue (2)Forcing the Issue (2)The force you feel CHANGES as you get closer.

Something closer to the black hole feels MORE force.

If you fall in feet first, you have a problem.

STRETTTTTCH!

There is a TideThere is a TideThe change in force is called a TIDE

Tides on surface of Earth (distance = 6400 km) : 1/1,000,000th of a g

DISTANCE FORCE (g)

6400 km 0.5

2000 18

1000 144

100 150,000

10150,000,000B

LA

CK

HO

LE

TID

ES

6400 km

Fup

Fdown

(for a 3 solar mass black hole)

The Second Way A The Second Way A Black Hole Can Kill YouBlack Hole Can Kill You

1.2.3.4.5.6.7.

Falling inSpaghettification

Why the long face?Why the long face?

The Third Way A Black The Third Way A Black Hole Can Kill YouHole Can Kill You

1.2.3.4.5.6.7.

Falling inSpaghettificationBe near one when it’s bornBe near one when it’s born

Cold War, Hot TopicCold War, Hot Topic

Vela Satellites flown to detect

nuclear explosions on Earthin 1960s and 1970s

by looking for gamma rays

Over their lifetime, they detected 73 events.

NOT ONE WAS OF THIS EARTH

Gamma Ray BurstsGamma Ray Bursts

GRBs happen every day, somewhere in the Universe

The Birth of a Black HoleThe Birth of a Black Hole

Hypernova!

Coalescing neutron stars

Birth PangsBirth PangsEnergy generated in a GRB = 1052 ergs

This is 10x the Sun’s total energy

over its entire lifetime.

Enough energy to vaporize the Earth

100 billion times over.

Pfffssssst!Pfffssssst!

NASA’s Swift ResponseNASA’s Swift Response

Swift detects

>100 GRBs per year

LaunchedNovember 20, 2004

The Fourth Way A Black The Fourth Way A Black Hole Can Hole Can KillKill You You

1.2.3.4.5.6.7.

Falling inSpaghettificationBe near one when it’s bornBe near one when it dies

Pare ProductionPare ProductionParticles created here

Buh bye!Free at last!

Black hole

Hawking Radiation:2 particles created, one particle leaves

Net Effect: Black holes radiate

away energy

Size Does MatterSize Does Matter

Hawking radiation depends on size/mass of the black hole:smaller holes radiate faster!

In fact, radiation emitted goes as 1/mass3

Stellar black hole lives for 1067 years

A mini black hole (mass =1012 kg)

would be exploding now

Emits higher energy radiation faster as size shrinks.

KABOOM!

The Fifth Way A Black The Fifth Way A Black Hole Can Kill YouHole Can Kill You

1.2.3.4.5.6.7.

Falling inSpaghettificationBe near one when it’s bornJust passing throughBe near one when it dies

notnot It’s a Wonderful Day in the It’s a Wonderful Day in the Neighborhood Neighborhood

What if . . .What if . . .

What would happenif the sun became ablack hole?

Solar System Black HoleSolar System Black Hole

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The Sixth Way A Black The Sixth Way A Black Hole Can Kill YouHole Can Kill You

1.2.3.4.5.6.7.

Falling inSpaghettificationBe near one when it’s bornJust passing throughBe nearby when they merge

Be near one when it dies

When Galaxies CollideWhen Galaxies Collide

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Wave Bye ByeWave Bye Bye

Gravitational waves expand and contract space itself

The Long and the Short of ItThe Long and the Short of It

ESA’s Response: LISAESA’s Response: LISA

3 “Wagon wheels”That will detect

passing gravitational

waves

Target launch: 2014

The Seventh Way A The Seventh Way A Black Hole Can Kill YouBlack Hole Can Kill You

1.2.3.4.5.6.7.

Falling inSpaghettificationBe near one when it’s bornJust passing throughBe nearby when they merge

Be near one when it dies

Fried by the light

Traveling CompanionTraveling CompanionHD 226868: just your typicalbloated supergiant star… but it has a secret

HD 226868 in X-rays(100,000x energy of Sun!)

Cygnus X-1

Hey, where is it?

The Hideous VortexThe Hideous Vortex

Disks and Fields and Jets, Oh MyDisks and Fields and Jets, Oh My

Not-so-compact DiskNot-so-compact Disk

Angry NeighborsAngry Neighbors

Cygnus A

M 87

(600 million light years)

(60 million light years)

Our GLAST (Fermi) ResortOur GLAST (Fermi) Resort

Gamma-RayLarge AreaSpace Telescope

Launched: June 2008

Fermi will see thousands

of active galaxies

The Seven Ways A Black The Seven Ways A Black Hole Can Kill YouHole Can Kill You

1.2.3.4.5.6.7.

Falling inSpaghettificationBe near one when it’s bornJust passing throughBe nearby when they merge

Fried by the light

Be near one when it dies

What’s on the other side…?What’s on the other side…?

Questions?Questions?

The Sky by EyeThe Sky by Eye

DIRBE’s Milky WayDIRBE’s Milky Way

EXTREME Close upEXTREME Close up

The Monster in the MiddleThe Monster in the Middle

Video DiskVideo Disk