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[Chicago Astronomer - Astro Joe]

Milky Way's Warp Explained

Washington, DC—A slow-motion collision between mysterious dark matter and two of the Milky Way’s galactic neighbors may be causing our galaxy to warp like a vinyl record left out in the hot Sun, scientists announced today.

Astronomers have puzzled over the Milky Way’s warped shape for nearly half a century but have been unable to provide a convincing explanation for what might be causing it.

The warp is most clearly visible in a thin disk of hydrogen gas that extends across the entire 200,000-light-year diameter of the Milky Way.

Viewed sideways, one half of the hydrogen disk appears to stick up above our galaxy’s plane of stars and gas, while the other half dips below the plane for a bit and then rises upward again farther away from the galaxy’s center.


Old theory, new twist

One early explanation was that the gravity from two neighboring dwarf galaxies known as the Magellanic Clouds was causing the Milky Way to warp as the pair moved in their 1.5-billion-year orbit around our galaxy.

This hypothesis was later dismissed after it was shown that the combined mass of the two dwarf galaxies is only about 2 percent of the Milky Way’s enormous hydrogen disk—not nearly enough to cause the warp.

Now researchers from the University of California, Berkeley have revived this old theory but with a new twist.

Using computer models, the team showed that the Magellanic Clouds could warp the shape of the Milky Way, but only if they were moving through a thick halo of hypothetical dark matter.

Dark matter can’t be directly observed because it neither emits nor reflects visible light or other electromagnetic radiation. However, its presence has been inferred from the gravitational effect it has on visible matter such as stars and galaxies. Astronomers believe that dark matter may make up as much as 90 percent of the mass in the universe.

Full story here from Space.com: www.space.com/scienceastronomy/060109_milkyway_warp.html

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For all we know, we could be in an irregular shaped galaxy or not even in one! The theory of us being in a pretty Andromeda shaped galaxy is merely speculation and I think we will be shocked on what our place actually looks like.

Earth is on the warped side...

[Maddad]

The computer model suggests that if the dwarf galaxies were moving through dark matter, then their gravitational influence would be enhanced to the point where they could cause warping similar to what has been observed.

I am not at all comfortable with this explanation. It is once again calling on the Dark Matter Tooth Fairy to bring them the presents they did not get for Christmas; a solid explanation of why things out there go the way they do.

Saying that the reason for the warpage of the disk is dark matter is insufficient. It does not explain why the dark matter warps. Tiny, low-mass dwarf galaxies herding unseen dark matter that masses ten times as much as the parent galaxy itself, therefore 500 times the mass of the dwarf galaxies, just does not fly. At some point they have to question whether they have the mechanism right. Dark matter may be a blind alley fiction.