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Quasars and Accretion Disk Model

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Questions and Answers

What could lead to a quasar having an arbitrarily high luminosity?

The gravitational pull of the central mass
A small supply of matter close to the black hole
Radiation pressure from the inner part of the accretion disk
A large supply of matter available sufficiently close to the black hole (correct)

What is the effect of radiation pressure on the accreting material in the accretion disk?

It directs the material inwards towards the central mass
It directs the material outwards, in opposition to the gravitational pull of the central mass (correct)
It increases the gravitational pull of the central mass
It decreases the accretion rate

What is the Eddington limit related to?

The black hole's mass
The accretion disk's temperature
The gravitational pull of the central mass
The maximum quasar luminosity for a fixed black hole mass (correct)

What would be the state of the hydrogen in the accretion flow at some stage?

Become ionized due to high-frequency radiation (B) Signup and view all the answers

What is the composition of the accretion flow after the hydrogen becomes ionized?

A mixture of unbound electrons and unbound protons in a plasma (C) Signup and view all the answers

Why is hydrogen considered the obvious candidate in the accretion flow?

It is the most abundant element in the Universe (C) Signup and view all the answers

What is the main reason why the electrons are not 'blown' away despite the strong radiation force on them?

A strong local electromagnetic restoring force prevents the separation of electrons and protons (B) Signup and view all the answers

Why is the gravitational force on the proton much stronger than that on the electron?

Because the proton is much more massive than the electron (B) Signup and view all the answers

What is the direction of the momentum of a photon moving radially outwards from a quasar?

Outwards away from the quasar (B) Signup and view all the answers

What is the main factor that determines the strength of the radiation force on an electron?

The charge of the electron (A) Signup and view all the answers

What is the net result of the competing forces of gravity and radiation pressure on a hydrogen atom?

The balance between the two forces determines the motion of the hydrogen atom (B) Signup and view all the answers

What is the reason why the radiation force on the electron is much greater than that on the proton?

The Thomson cross-section scales inversely with the square of the particle's mass (A) Signup and view all the answers

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