Calculating the Feeding Rate of Supermassive Black Holes to Power Quasars

In summary, quasars are formed when supermassive black holes consume gas or stars, with typical masses of 10^7 solar masses and luminosities of 10^39 W. In order to power this luminosity, one of these black holes must consume a certain amount of stars per year, which can be calculated using the equation L = GM/R * deltaM/deltaR, where deltaM and deltaR represent the rate of accretion. By plugging in the given values and the Schwarzschild radius, one can solve for deltaM and deltaR. The units on the resulting value for deltaM/deltaR will depend on the units used for mass and distance in the equation.
  • #1
amt2124
3
0

Homework Statement


Quasars arise when supermassive black holes swallow nearby gas, or even
entire stars. Their masses are typically 10&7 solar masses, and their luminosities are
typically around 10&39 W. Hide the children! Roughly how many stars must one of
these monsters eat per year, in order to power that luminosity?

Homework Equations



L = GM/R * deltaM/deltaR

The Attempt at a Solution


So far I can find deltaM/deltaR like the professor said we should. I am having trouble understanding where we go from there.
 
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  • #2
amt2124 said:
So far I can find deltaM/deltaR like the professor said we should. I am having trouble understanding where we go from there.
Perhaps you can expound a bit upon what deltaM and deltaR are, and how you have found them?
 
  • #3
gneill said:
Perhaps you can expound a bit upon what deltaM and deltaR are, and how you have found them?
I assumed that I am able to plug in the schwarzschild radius for the radius, G is a constant, and I am given the luminosity and mass. When I plug those in I can solve for deltaM and deltaR (which is the rate of accretion).
 
  • #4
Can you show the algebra that you did, plugging the Schwarzschild radius into your luminosity equation?
 
  • #5
gneill said:
Can you show the algebra that you did, plugging the Schwarzschild radius into your luminosity equation?
 

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  • #6
Okay. Now what are the units on your ΔM/ΔR value?
 

1. What is accretion?

Accretion is the process by which matter, such as gas or dust, falls onto a central object due to gravity. In the context of astrophysics, this typically refers to the accretion of material onto a black hole or a young star.

2. How do accretion disks form around black holes?

As matter falls towards a black hole, it begins to spin faster and faster due to conservation of angular momentum. This creates a disk-like structure, known as an accretion disk, around the black hole. The accretion disk is heated by friction and can emit intense radiation, making it visible as a quasar.

3. What is a quasar?

A quasar, short for quasi-stellar object, is an extremely bright and distant object in space that is powered by the accretion of matter onto a supermassive black hole. Quasars are among the most luminous objects in the universe and are thought to be the early stages of galaxy formation.

4. How are quasars used to study the early universe?

Quasars are extremely bright and can be seen from very far distances, making them useful tools for studying the early universe. By observing the light from quasars, scientists can learn about the composition and evolution of the universe in its early stages.

5. What role do quasars play in galaxy formation?

Quasars are thought to be the early stages of galaxy formation, as the intense radiation emitted from the accretion disk can heat up surrounding gas and trigger the formation of stars. Additionally, the supermassive black holes at the center of quasars play a crucial role in regulating the growth of galaxies through their powerful jets and outflows.

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