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Sometime during the last couple of weeks, during which I've been doing a lot of poking around on this forum and various other sources on the internet, I ran across something to which, unfortunately, I have lost the reference. It may even have been off of a link somewhere in this (cosmology) forum.
What it said, and I did not expect this, and don't understand it, is that there have been measurements of the state of things around a pair of galaxies that collided sometime in the past and the results were that while the normal matter of each galaxy was, on average, slowed by the merging of the two galaxies (which I would expect) and the result was a single misshapen galaxy but that the globes of dark matter from each moved out past the merged galaxies thus resulting in 3 blobs, the merged galaxies and 2 blobs of dark matter.
Since
This does not make sense to me. It is possible that I somewhat misremember the EXTENT of the lack of interaction of the two types of matter, but what I am SURE I do not misremember is that there were, exactly as I decribed above, 3 blobs (this was shown graphically ... as I recall, the whole thing was a cartoon type illustration, all of which made sense to me except for this one part.)
Thanks for any help you can give me to understand this phenomenon. If the whole thing seems preposterous, I'll dig around more and see if I can find the reference to get more information.
What it said, and I did not expect this, and don't understand it, is that there have been measurements of the state of things around a pair of galaxies that collided sometime in the past and the results were that while the normal matter of each galaxy was, on average, slowed by the merging of the two galaxies (which I would expect) and the result was a single misshapen galaxy but that the globes of dark matter from each moved out past the merged galaxies thus resulting in 3 blobs, the merged galaxies and 2 blobs of dark matter.
Since
- dark matter seems to interact gravitationally in the same way that normal matter does
- even a galaxy has very low density, so the slowing of the galaxies during the collision is NOT due to stars smashing together
This does not make sense to me. It is possible that I somewhat misremember the EXTENT of the lack of interaction of the two types of matter, but what I am SURE I do not misremember is that there were, exactly as I decribed above, 3 blobs (this was shown graphically ... as I recall, the whole thing was a cartoon type illustration, all of which made sense to me except for this one part.)
Thanks for any help you can give me to understand this phenomenon. If the whole thing seems preposterous, I'll dig around more and see if I can find the reference to get more information.