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
The general theory of relativity is our most accurate description of gravitation
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
Supermassive black holes exist at the centers of of most galaxies
Black holes evaporate spacetime, or even some other universe?
Black Holes have no Hair spacetime, or even some other universe?
Properties of a black hole:
- Spin (angular momentum)
- Charge (tends to be zero)
Black Holes can have impact on their environments spacetime, or even some other universe?
Do Black Holes Really Exist? Good Candidate: Cygnus X-1 spacetime, or even some other universe?
- Binary system: 30 MSun star with unseen companion.
- Binary orbit => companion > 7 MSun.
- X-rays => million degree gas falling into black hole.
An early gamma ray-burst spacetime, or even some other universe?
A Gamma Ray Burst Sampler spacetime, or even some other universe?
Great debate: 1967-1997 spacetime, or even some other universe?
Naked-eye visible for ~30 sec. Distance = 7.5 billion ly
Uh-oh spacetime, or even some other universe?
GRB Host spacetime, or even some other universe?
Bloom et al. 2002
GRB 970508 spacetime, or even some other universe?
Taylor et al 1997
GRB Expansion spacetime, or even some other universe?
Relativistic Expansion v ~ 0.96c
E ~ 10^53 ergs
R ~ (E/n)^1/8
Taylor et al 2004
Pihlstrom et al 2007
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)
Hjorth et al 2003
Final States of a Star curves
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
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
Where do most GRBs occur:
A: in globular clusters
B: in star forming regions
C: in old open clusters
D: in the Oort cloud
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.
NS-NS binary curves
Coalescence versus Collapse