Black hole mass vs galaxy mass

In summary: A supermassive black hole at the center of a galaxy can grow to be millions of times more massive than the sun over the course of a few billion years by accretion of material from smaller black holes and stars.
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wolram
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What is the origin of the M-sigma relation between supermassive black hole mass and galaxy velocity dispersion?] How did the most distant quasars grow their supermassive black holes up to 109 solar masses so early in the history of the Universe?
 
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  • #2
wolram said:
What is the origin of the M-sigma relation between supermassive black hole mass and galaxy velocity dispersion?] How did the most distant quasars grow their supermassive black holes up to 109 solar masses so early in the history of the Universe?
This is an area of active research and is as yet unknown. The physics of black holes and the matter around them are horrifically complex.

Here's one fairly recent article that talks about one of the mechanisms that is relevant:
http://sci.esa.int/herschel/50333-powerful-black-holes-quenched-galaxy-star-formation/
 
  • #3
Astronomers had long suspected that black holes could exert such negative feedback on their host galaxy: the accretion process of matter onto a black hole is not completely efficient and can thus drive large amounts of the galaxy's interstellar matter outwards. These black-hole triggered winds would then deprive galaxies of the raw material needed to form stars. In recent years, evidence has mounted in support of this scenario; among others, a survey of galaxies performed with Herschel has shown, in 2011, that galactic outflows are indeed able to influence the entire galaxy's star formation.

What are these (winds) how are they produced?
 
  • #4
wolram said:
Astronomers had long suspected that black holes could exert such negative feedback on their host galaxy: the accretion process of matter onto a black hole is not completely efficient and can thus drive large amounts of the galaxy's interstellar matter outwards. These black-hole triggered winds would then deprive galaxies of the raw material needed to form stars. In recent years, evidence has mounted in support of this scenario; among others, a survey of galaxies performed with Herschel has shown, in 2011, that galactic outflows are indeed able to influence the entire galaxy's star formation.

What are these (winds) how are they produced?
I believe it's primarily radiation pressure from the active galactic nucleus acting on the galaxy's gas and dust.
 

1. What is the relationship between black hole mass and galaxy mass?

The relationship between black hole mass and galaxy mass is known as the "M-σ" relation, which states that the mass of a galaxy's central supermassive black hole is directly proportional to the mass of the galaxy's bulge. This means that the larger the galaxy's mass, the larger the mass of its black hole.

2. How do black holes and galaxies form?

Black holes and galaxies are formed through a process known as hierarchical merging. As smaller galaxies merge together, their central black holes also merge, resulting in a larger black hole and a more massive galaxy.

3. Why is the mass of a black hole important?

The mass of a black hole is important because it affects the structure and evolution of its host galaxy. A more massive black hole exerts a stronger gravitational pull, which can influence the orbits of stars and gas within the galaxy. This can also affect the galaxy's ability to form new stars.

4. How is the mass of a black hole measured?

The mass of a black hole can be measured in several ways, including through the observation of the orbital motion of stars and gas around the black hole, the measurement of X-ray emission from matter falling into the black hole, and the detection of gravitational waves produced by merging black holes.

5. Can the mass of a black hole change?

Yes, the mass of a black hole can change over time as it accretes matter from its surroundings. This is particularly true for active galactic nuclei, where the black hole is actively feeding on gas and stars, causing its mass to increase. However, in general, the mass of a black hole remains fairly constant once it has reached a steady state.

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