Lecture 30 — Black Holes: Manifestations of GR

Reminders

1 Online Quiz Chapter 14 2 Read Chapter 14 3 Midterm 3 Friday Nov 20 (a week from Friday)

1 Lecture 30 — Black Holes: Manifestations of GR

2 Clicker Question

Novae occur because (a) runaway thermonuclear fusion of hydrogen on the surface (b) the hydrogen has time to cool and is supported by quantum mechanical pressure of electrons (c) Carbon and Oxygen fusion runs away in the center (d) both (a) and (b)

3 Clicker Question

In Type Ia supernovae, the white dwarf reaches the Chandrasekhar mass and explodes because (a) there is runaway thermonuclear fusion of hydrogen on the surface (b) the hydrogen does not have time to cool burns to Carbon and Oxygen non-degenerately (supported by ordinary thermal pressure) (c) Carbon and Oxygen fusion runs away in the center due to the fact that white dwarfs are supported by quantum mechanical pressure. (d) both (b) and (c) 4 Clicker Question

Nearly all the Carbon in the Universe is produced in (a) Core collapse supernovae (b) Type Ia supernovae (c) All types of supernovae (d) during CNO burning

5 Gravitational Redshift

Doppler shift is due to motion of source and wave nature of light

But light, or photons have energy Eγ = hν Takes energy to escape gravitational ﬁeld → photon loses energy climbing out of gravitational ﬁeld → photon is redshifted gravitationally

6 7 Gravitational Redshift

8 What if escape Velocity > c?

9 Black Holes

Schwarzschild Radius 2GM M R = = ( ) S 2 3 km c M Event Horizon Nature Abhors a naked singularity Black holes have no hair Black hole radiation Time dilation in coordinate time

10 Black Hole: Singularity + Event Horizon

11 Black Hole Recap

Schwarzschild Radius 2GM M R = = ( ) S 2 3 km c M Event Horizon Nature Abhors a naked singularity Black holes have no hair Black hole radiation Time dilation in coordinate time

12 Falling Into a Black Hole

13 Cygnus X-1: Candidate Black Hole M > 3.8 M

14 SS 433: Microquasar

15 Gamma Ray Bursts (GRB)

Discovered by Vela Satelites About 1 a day SWIFT Collapsar Model Magnetars

16 Gamma Ray Bursts

17 Some Gamma Ray Bursts are Associated with SNe

18 Short Gamma Ray Bursts are Associated with Magnetars