The genesis and characteristics of black

holes

Marion Mikusch Physics institute, university of Graz

The contraction of a gas cloud molecules: do not have enough Ekin triggers: compressions Jeans mass and Jeans radius:

contraction Epot is released if heat is transported off collapse free falling time: protostar is born

A collapse sets in…

Different phases:

◦ hydrogen burning◦ helium burning◦ carbon, neon, oxygen, silicate burning

stage of equilibrium until fuel is depleted a new thermonuclear process starts Stars over 8 sm: also heavy elements are

built iron-nickel core is formed supernova

Stage of nucleosynthesis

neutron star: e+pn

until internal pressure prevents contraction

Star over 30 sm: unstoppable collapse a black hole is born

The unstoppable collapse

escape velocity reaches the speed of light

Schwarzschild radius: causal border

black hole with 10 sm: Rs = 29,5 km

event horizon: surface around the black hole

A black hole swallows everything…

interstellar matter approches in spiral tracks

X-ray emission

rotation space-time geometry is distorted

‘electromagnetic tornado‘

Accretion disc and matter jets

analogy between event horizon and entropy

entropy: disorder of missing information in a system

bit of information area of the event horizon

definition of entropy and temperature is possible

thermodynamical description

paradox: finite temperature emission of thermal radiation??

Quantum mechanics: uncertainty principle virtual particles can arise in pairs

they disengage for a short time and than annihilate

mass of the black hole decreases

total evaporation

Hawking radiation

Only 3 observable characteristics:

◦ mass◦ angular momentum◦ electric charge

huge information loss

but a swallowed bit is ‘saved‘ in an area of the event horizon like a hologram

3-dimensional object memorized by a 2-dimensional region

holographic principle