Why does the amount of dark matter increase the further away from the

In summary, dark matter in galaxies does not appear to be randomly distributed. It has a tendency to "yo-yo" in and out of the local center of gravity, gaining velocity as it approaches and slowing as it exits. The distribution of dark matter is likely a result of how different galaxies formed and it is not affected by most normal astrophysical reactions. Without a way to measure its peculiar velocity, the best we have are computer models to understand its behavior.
  • #1
sytric
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Why isn't the dark matter just randomly distributed? How does it know where to go? Why does the amount of dark matter increase the further away from the galaxy's center?
 
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  • #2
Dark matter yo-yo's in and out of the local center of gravity. It gains velocity as it approaches the center of gravity and slows as it exits. Because of its low velocity in the 'halo' region, it tends to spend more time there.
 
  • #3
sytric said:
Why isn't the dark matter just randomly distributed? How does it know where to go? Why does the amount of dark matter increase the further away from the galaxy's center?

You might ask the same questions about visible matter in Galaxies. It is not evenly distributed either, especially not in spiral galaxies.

The distribution of mass is likely a result how how different galaxies formed.

We do not believe dark matter would be changed by most normal astrophysical reactions other than gravity (friction, for instance), so where it tends to settle would be different than where normal baryonic matter would settle.
 
  • #4
vociferous said:
We do not believe dark matter would be changed by most normal astrophysical reactions other than gravity (friction, for instance), so where it tends to settle would be different than where normal baryonic matter would settle.

Yes, but the point is more that it probably DOESN'T "settle". As Chronos pointed out, it yo-yos from one side of the galaxy to the other
 
  • #5
I have the same issue with long-period comets. It's almost as if they're avoiding us.
 
  • #6
zyxwv99 said:
I have the same issue with long-period comets. It's almost as if they're avoiding us.

You think it was something we said? :smile:
 
  • #7
phinds said:
Yes, but the point is more that it probably DOESN'T "settle". As Chronos pointed out, it yo-yos from one side of the galaxy to the other

I do not think anything really "settles", but without a way to measure the peculiar velocity of dark matter (as far as I know), I think the best we have are computer models.
 

1. Why does the amount of dark matter increase the further away from the center of a galaxy?

The amount of dark matter increases as you move away from the center of a galaxy due to the distribution of matter in the galaxy. Dark matter is thought to make up a significant portion of a galaxy's mass, and its density decreases as you move away from the center. This means that the further away you go, the more dark matter there is relative to visible matter.

2. How does dark matter affect the rotation of galaxies?

Dark matter plays a crucial role in the rotation of galaxies. Without dark matter, galaxies would not have enough mass to hold together and would spin too quickly. The gravitational pull of dark matter helps to keep galaxies from flying apart due to their rapid rotation.

3. Why is dark matter invisible?

Dark matter is invisible because it does not interact with light or other forms of electromagnetic radiation. This means that it does not emit, absorb, or reflect light, making it difficult to detect using traditional telescopes. Scientists can only infer the presence of dark matter through its gravitational effects on visible matter.

4. How is dark matter different from regular matter?

Dark matter and regular matter are fundamentally different because they interact with the universe in different ways. Regular matter is made up of atoms and particles that interact with electromagnetic radiation, while dark matter does not. Additionally, dark matter accounts for a much larger portion of the universe's mass, while regular matter only makes up a small fraction.

5. What are some theories about the origin of dark matter?

There are several theories about the origin of dark matter, but the most widely accepted one is the cold dark matter theory. This theory suggests that dark matter is made up of weakly interacting massive particles (WIMPs) that were created in the early universe. Other theories propose that dark matter could be made up of primordial black holes, axions, or other exotic particles. However, the exact nature and origin of dark matter are still being studied and debated by scientists.

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