The general theory of relativity is our most accurate description of gravitation
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The general theory of relativity is our most accurate description of gravitation. Published by Einstein in 1915, this is a theory of gravity A massive object causes space to curve and time to slow down These effects manifest themselves as a gravitational force

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The general theory of relativity is our most accurate description of gravitation

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The general theory of relativity is our most accurate description of gravitation

The general theory of relativity is our most accurate description of gravitation

  • Published by Einstein in 1915, this is a theory of gravity

  • A massive object causes space to curve and time to slow down

  • These effects manifest themselves as a gravitational force

  • These distortions of space and time are most noticeable in the vicinity of large masses or compact objects


The general theory of relativity is our most accurate description of gravitation

The general theory of relativity also predicts the existence of

gravitational waves, which are ripples in the overall geometry of

space and time produced by moving masses

Gravitational waves have been detected indirectly, and specialized

antennas are under construction to make direct measurement

of the gravitational waves from cosmic cataclysms


The general theory of relativity is our most accurate description of gravitation

  • If a stellar corpse has a mass greater than about 2 to 3 M, gravitational compression will overwhelm any and all forms of internal pressure

  • The stellar corpse will collapse to such a high density that its escape speed exceeds the speed of light


The general theory of relativity is our most accurate description of gravitation

Supermassive black holes exist at the centersof most galaxies

  • These are detected by observing the motions of material around the black hole


The general theory of relativity is our most accurate description of gravitation

Falling into a black hole is an infinite voyage


The general theory of relativity is our most accurate description of gravitation

  • Could a black hole somehow be connected to another part of spacetime, or even some other universe?

  • General relativity predicts that such connections, called wormholes, can exist for rotating black holes


The general theory of relativity is our most accurate description of gravitation

Black holes evaporate


The general theory of relativity is our most accurate description of gravitation

Black Holes have no Hair

Properties of a black hole:

- Mass

- Spin (angular momentum)

- Charge (tends to be zero)


The general theory of relativity is our most accurate description of gravitation

Black Holes can have impact on their environments


The general theory of relativity is our most accurate description of gravitation

Do Black Holes Really Exist? Good Candidate: Cygnus X-1

- Binary system: 30 MSun star with unseen companion.

- Binary orbit => companion > 7 MSun.

- X-rays => million degree gas falling into black hole.


The general theory of relativity is our most accurate description of gravitation

An early gamma ray-burst

Vela satellite


The general theory of relativity is our most accurate description of gravitation

A Gamma Ray Burst Sampler


The general theory of relativity is our most accurate description of gravitation

Great debate: 1967-1997


Bepposax satellite

Bepposax Satellite

GRBM:

40-600 keV

WFC: 2-30

keV

NFI: 2-10

keV


X ray afterglow from grb 971214

X-Ray Afterglow from GRB 971214

t=6.5 hrs

t=12.5 hrs

t=54 hrs


Optical afterglow from grb 971214

Optical Afterglow from GRB 971214

Keck

Images

2 days

2 months

Host

HST Image


Optical afterglow from grb 080319b

Optical Afterglow from GRB 080319b

Swift Image

Light Curve

Naked-eye visible for ~30 sec. Distance = 7.5 billion ly


The general theory of relativity is our most accurate description of gravitation

Uh-oh


The general theory of relativity is our most accurate description of gravitation

GRB Host

Galaxies

Bloom et al. 2002


Radio light curves from long grbs

Radio Light Curves from long GRBs


The general theory of relativity is our most accurate description of gravitation

GRB 970508

  • First VLBI detection of a GRB Afterglow

  • absolute position to < 1 mas

  • Size < 10^19 cm (3 lt years)

  • Distance > 10000 lt years

Taylor et al 1997


The general theory of relativity is our most accurate description of gravitation

GRB Expansion

Relativistic Expansion v ~ 0.96c

E ~ 10^53 ergs

(isotropic equivalent)

R ~ (E/n)^1/8

Taylor et al 2004

Pihlstrom et al 2007


The evidence long grbs

Peak toward low end of gamma-ray, complex gamma-ray light curves

Often have bright afterglows

Evidence for a relativistic explosion

Energy required of ~ 1053 ergs (isotropic)

Associated with regions of star formation in distant galaxies (out to edge of observable universe)

Sometimes obscured by dust

Plus …

The Evidence (long GRBs)


Example supernova 1998bw

Example Supernova: 1998bw


The general theory of relativity is our most accurate description of gravitation

Long GRBs clearly connected to Supernovae

Hjorth et al 2003


The general theory of relativity is our most accurate description of gravitation

Final States of a Star

1. White Dwarf

If initial star mass < 8 MSun or so

2. Neutron Star

If initial mass > 8 MSun and < 25 MSun

3. Black Hole

If initial mass > 25 MSun

No Event + PN

Supernova + ejecta

GRB + Supernova + ejecta


Clicker question

Clicker Question:

What is the remnant left over from a GRB?

A: a white dwarf + expanding shell

B: a neutron star + expanding shell

C: a black hole + expanding shell

D: no remnant, just the expanding shell


Clicker question1

Clicker Question:

Where do most GRBs occur:

A: in globular clusters

B: in star forming regions

C: in old open clusters

D: in the Oort cloud


Clicker question2

Clicker Question:

What was the subject of the great debate about GRBs that went on for ~30 years?

A: If they were produced by Supernovae or colliding stars.

B: If they were galactic or extragalactic in origin.

C: If they were of terrestrial or extraterrestrial in origin?

D: If a nearby GRB killed off the dinosaurs.


The general theory of relativity is our most accurate description of gravitation

NS-NS binary

Massive star

Coalescence versus Collapse


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