PHYS 005 Lecture Notes - Lecture 14: Seyfert Galaxy, Active Galactic Nucleus, Donut
5 Jul 2018
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Session 14 (Session 16) Supermassive Black Holes, Accretion Disks and Jets
Ch. 25, Sect. 4,5
How big is the central black hole that is creating the quasr?
●Use Eddington Limit
○Applies to everything bound by gravity
○Radiation pressure- light/whatever produces energy
■Photons that try to escape object-> creates radiation pressure
■Brighter it is, the more radiation it produces
○DIRECTLY related to MASS OF BLACK HOLE
■Higher the mass, higher the limit
■Bigger- brighter accretion disk, smaller- dimmer accretion disk
Radiometer Demo
●Light makes the thing spin (accretion disk spin)
If radiation of accretion disk > Eddington limit, the black hole has no more fuel
●Small-mass black hole
○Not too bright- things DON’T fall into black hole
○Too bright- radiation pressure pushes material away
●Massive black hole
○Bright- material not falling
○Not bright- material not falling
○Too bright- pushes material away
●-> small-mass black hole doesn’t have to be too bright before things start being pushed away
Black holes in quasars found to be super-massive
●Black holes suck everything in including other black holes to be supermassive, but more may be
created by:
●Massive galaxy collisions created the supermassive black holes
2,000x more bright
●Due to material that falls in
How does it get so hot?
●Kepler’s Laws- closer gas blob is to center of the disk, faster its orbital speed
○Inner & outer layers rub agst each other
●So hot- 1,000 degrees that it glows in UV/ x-rays
Jets in quasars
●NOT created in hole- is what OUTSHINES the whole galaxy
●**NOT material escaping fr black hole
●Moving @ speed of light- relativistic speed
Document Summary
Session 14 (session 16) supermassive black holes, accretion disks and jets. Photons that try to escape object-> creates radiation pressure. Brighter it is, the more radiation it produces. Directly related to mass of black hole. Bigger- brighter accretion disk, smaller- dimmer accretion disk. Light makes the thing spin (accretion disk spin) If radiation of accretion disk > eddington limit, the black hole has no more fuel. Not too bright- things don"t fall into black hole. Too bright- radiation pressure pushes material away. > small-mass black hole doesn"t have to be too bright before things start being pushed away. Black holes in quasars found to be super-massive. Black holes suck everything in including other black holes to be supermassive, but more may be created by: Massive galaxy collisions created the supermassive black holes. Kepler"s laws - closer gas blob is to center of the disk, faster its orbital speed. Inner & outer layers rub agst each other.
