High energy Astrophysics Mat Page Mullard Space Science Lab, UCL Revision lecture

Revision lecture: This lecture: Quick race through the course! Intended to inspire you to look back through your notes!

1: What is high energy astrophysics? High energy because: –Photons emitted above 100 eV (X-ray sources) –Large energy density in photon field or magnetic field, (eg X-ray binaries, pulsars) –Large amount of energy stored in gravitational field (eg Black holes) Unusually high concentrations of energy

X-rays from stellar photospheres? Take the Sun. T=5800K XUIV R

X-ray, -ray and radio skies

2: The whole range of X-ray sources

3: emission mechanisms

4+5: accreting X-ray binaries

accretion efficiency How much energy can we get from accretion compared to fusion? Energy released per unit mass of material accreted = GM/R Energy equivalent per unit rest mass = c 2 So we can consider the efficiency of accretion to be GM/(Rc 2 ) For a white dwarf this is ~ 1.5 x Fusion of hydrogen converts of rest mass to energy so we could say this has an efficiency of 0.7%

6: radio galaxies e.g. Faranoff-Riley 1 galaxy

shell-like filled in Cas A Crab 7: supernova remnants

8: AGN

9: The X-ray background

Coma cluster 10: Masses of hot gas

11: Gamma-ray bursts

Burst lightcurves

12: Cosmic rays

13: Gravitational waves

14: The Galactic centre

15: The future!