The genesis and characteristics of black holes

1. The genesisandcharacteristicsofblackholes Marion Mikusch Physicsinstitute, universityof Graz

2. The contractionof a gas cloud • molecules: do not haveenoughEkin • triggers: compressions • Jeans massand Jeans radius:

3. A collapsesets in… • contraction Epotisreleased • ifheatistransported off collapse • freefalling time:  protostarisborn

4. Stage ofnucleosynthesis • Different phases: • hydrogen burning • heliumburning • carbon, neon, oxygen, silicateburning • stageofequilibriumuntilfuelisdepleted •  a newthermonuclearprocessstarts • Stars over 8 sm: also heavy elementsarebuilt • iron-nickelcoreisformed  supernova

5. The unstoppablecollapse • neutronstar: e+pn • untilinternalpressurepreventscontraction • Star over 30 sm: unstoppablecollapse  a black hole isborn

6. A black hole swallowseverything… • escapevelocityreachesthespeedoflight • Schwarzschild radius:  causalborder • black hole with 10 sm: Rs = 29,5 km • eventhorizon: surfacearoundtheblack hole

7. Accretiondiscand matter jets • interstellar matter approches in spiral tracks • X-rayemission • rotation  space-time geometryisdistorted • ‘electromagnetictornado‘

8. thermodynamicaldescription • analogybetweeneventhorizonandentropy • entropy: disorderofmissinginformation in a system • bitofinformation areaoftheeventhorizon • definitionofentropy andtemperature ispossible

9. Hawking radiation • paradox: finite temperature emissionof thermal radiation?? • Quantum mechanics: uncertaintyprinciple  virtualparticlescanarise in pairs • theydisengagefor a short time andthanannihilate • massoftheblack hole decreases  total evaporation

10. holographicprinciple • Only 3 observable characteristics: • mass • angular momentum • electriccharge • hugeinformationloss • but a swallowedbitis ‘saved‘ in an areaoftheeventhorizon  like a hologram • 3-dimensional objectmemorizedby a 2-dimensional region

11. Thankyouforyourattention!