Why is our galaxy's dark matter distribution non-spherical?

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In summary, our galaxy is planar because of its rotational kinetic energy, which is caused by tidal torques from other galaxies. While the dark matter in the halo may be distributed spherically, the gas in the galaxy is clearly in a disk. However, due to the non-interacting nature of dark matter, it cannot organize itself into a disk structure despite its rotation. The process of how our galaxy obtained its rotation is still not fully understood, but the current theory suggests it was due to interactions with other galaxies before its collapse.
  • #1
magickingdl
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Why is our galaxy planar? Why isn't it spherical?
 
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  • #2
Because it has rotational kinetic energy -- it's spinning.

- Warren
 
  • #3
chroot said:
Because it has rotational kinetic energy -- it's spinning.

Though it's worth mentioning that the process by which it obtained that rotation is still relatively unclear. Our best theory at the moment is that it was due to tidal torques from other pre-collapse galaxies.
 
  • #4
I think its more spherical than it looks. There's lots of dark matter in the halo.
 
  • #5
tony873004 said:
I think its more spherical than it looks. There's lots of dark matter in the halo.

That depends on what you're referring to. The dark matter distribution is indeed thought to be spherical (roughly), but the gas is clearly in a disk. The fact that the dark matter is non-interacting means that it wouldn't be able to organize itself into a disk structure despite having non-zero rotation.
 

1. Why is our galaxy planar?

Our galaxy, the Milky Way, is planar because it formed from a rotating disk of gas and dust. As the gas and dust collapsed under gravity, it began to rotate faster and flatten into a disk shape due to centrifugal force. This is a common occurrence in the formation of spiral galaxies.

2. What factors contribute to the planar shape of our galaxy?

The main factors that contribute to the planar shape of our galaxy include gravity, rotation, and gas dynamics. Gravity pulls the gas and dust inwards, while rotation and gas dynamics cause the material to flatten into a disk shape.

3. Are all galaxies planar?

No, not all galaxies are planar. There are different types of galaxies, such as elliptical and irregular, which do not have a distinct disk shape. However, the majority of spiral galaxies, including our own, have a planar shape.

4. How does the planar shape of our galaxy affect us?

The planar shape of our galaxy has a significant impact on our view of the night sky. As we are located within the disk, we see a band of stars and dust known as the Milky Way. This band is composed of stars and gas clouds within our galaxy.

5. Can the planar shape of our galaxy change over time?

While the overall shape of our galaxy is stable, there is evidence that the disk may experience minor changes over time. For example, interactions with other galaxies or dark matter halos can cause the disk to warp or ripple. However, these changes are relatively small and do not significantly alter the overall planar shape of our galaxy.

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