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Black Holes Spin!. by Paola Rebusco. MIT, April 22nd 2009. BH have NO HAIR. By J.A. Wheeler. Black Holes’ Anatomy. Once they form they are left with ……… Mass Spin Charge. km. miles. Some History.

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slide1

Black Holes Spin!

by Paola Rebusco

MIT, April 22nd 2009

slide2

BH have NO HAIR

By J.A. Wheeler

slide3

Black Holes’ Anatomy

Once they form they are left with

……… Mass

Spin

Charge

km

miles

some history

Some History

John Michell (1784) and Pierre-Simon Laplace (1796) propose the existence of “dark stars”…that lock in light (in Newtonian mechanics)

Albert Einstein publishes his first paper on GR (1915)

Karl Schwarzschild finds black holes as a solution to Einstein’s equations (1916)

Subrahmanyan Chandrasekhar suggests that a massive star can collapse into something denser (1930)

Robert Oppenheimer and Hartland Snyder predict that massive stars can collapse into black holes (1939)

Roy Kerr finds the solution for rotating black holes (1963)

Stephen Hawking considers quantum effects: quantum black holes are different from classical black holes (1974)

a farm picture

THROUGH the ample open door of the peaceful country barn,

A sun-lit pasture field, with cattle and horses feeding;

And haze, and vista, and the far horizonS, fading away..

AFarm-Picture

Walt Whitman - Leaves of Grass 1900

slide6

region

http://nrumiano.free.fr/Images/tn_kerr_E.gif

slide7

Frame-dragging

TEST: Gravity Probe B

slide9

QUIZ

What would happen to the Earth’s orbit IF the Sun was to be replaced by a black hole of the same mass and spin?

slide10

IF black holes exist…

how do they form?!

life cycle of massive stars

REMEMBER: gravity against pressure gradient

  • High Temperature and Pressure: successive fusion reactions!

Life Cycle of Massive Stars

Fusing H into He, He into C,O, …and so on into Fe

Carbon Burning

Oxygen Burning

slide12

Iron is the most stable…

Supernovae Type II and Hypernovae!

  • Collapse..250000000 km/h!
  • More energy released than our Sun in billions of years!

What is left?

slide15

YEAH!

a=0.75-0.90 (Gammie et al 2004)

slide16

Mergers!

Short

Gamma

Ray

Bursts

NOTE: spin up

intermezzo quantum or not quantum

INTERMEZZO: Quantum or Not Quantum?

Any black hole emits Hawking black body radiation with

The characteristic time for quantum effectsis

For MBH= 1 MSUN ….

slide18

QUIZ

The energy reached by the Large Hadron Collider MAY produce micro black holes ( )…if this were to occur, would it be dangerous?Why?

commercial break further reading

Commercial Break!!!(Further Reading)

  • Schutz, B. A First Course in General Relativity
  • Carroll, S. An Introduction to General Relativity: Spacetime and Geometry
  • D’Inverno, R. Introducing Einstein's Relativity
  • Wald, Robert. General Relativity
  • Hartle J. An Introduction to Einstein’s General Relativity
  • Thorne, K. Black Holes and Time Warps: Einstein's Outrageous Legacy
  • Begelman M. & Rees M. Gravity’s Fatal Attraction: BH in the Universe
  • Ferguson K. Prisons of Light -Black Holes
slide20

Do Black Holes Exist?

  • Lasciate ogni speranza,
  • o voi ch’entrate.
  • Abandon all hope,
  • you who enter here.
  • Dante Alighieri
  • (Divina Commedia-Hell)

Artist impression

John Wheeler 1967- Physics Today

black holes are not alone

Black Holes are not Alone!

Binaries (BH+Companion)

Live in Galaxies

Affect the Motion of Stars

slide22

X-ray Binaries

Artist impression

slide23

Shakura & Sunyaev model (1973)

Thin disks:

  • h/r<<<1 neglect higher order terms
  • l=lk, : keplerian angular momentum
  • Viscosity prescription - (molecular viscosity is not enough)
1972 cygnus x 1

1972: Cygnus X-1

  • The first black hole candidate!!!!!!!
  • A blue supergiant (optically bright, X-ray dim) orbits an unseen (optically, but bright X-ray) companion!
  • Rapid X-ray variability
slide25

Some X-ray Telescopes

RXTE

Timing

XMM Newton

Spectroscopy

Chandra

Imaging

slide27

Radio Galaxies

(A type of galaxy with an Active Galactic Nucleus=AGN)

  • fast (less than 1 yr) change in time
  • A lot of power in a small space
  • - Superluminal jets!
slide28

Supermassive Black Holes powering AGN!!!

NGC 1275 is

very active…

(radio,X,GAMMA)

(Credit: Radio: NRAO/AUI/NSF)

slide30

..or quiet : Sagittarius A*

Infrared Observation

1 light year = 9.4605284 1015 m

slide32

Where the disk ‘ends’….

ISCO (depends on the spin)

spin measurements

Spin Measurements

  • Relativistic Lines -
  • Relativistic Doppler Shift
  • and gravitational red shift
  • STRONGEST at the ISCO
  • Accretion disk continuum -
  • Closer is hotter

(Miller et al 09)

spin measurements1

Spin Measurements

  • Quasi Periodic Oscillations -
  • Lie in the range
  • of ORBITAL FREQUENCIES
  • of geodesics close to the
  • ISCO
  • Reverberation (measure time lags between variations in the continuum and in emission lines)
  • Polarimetry (the rotation angle is energy -> radius dependent)

Courtesy of R.Remillard

test gr what happens at the singularity understand quantum gravity

Other (many) challenges!

Test GR

What happens at the singularity? Understand Quantum Gravity!!!!!