Missing Milky Way Dark Matter: Surprising Constraints on the Lambda-CDM Model

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
Sign up Log in
7 replies · 4K views
Grep
Messages
298
Reaction score
3
Astronomy news on Phys.org


Grep said:
It introduces what seems to be rather tight constraints on the dark disc.

Really interesting.

What effect might this have on the Lambda-CDM model, for example?

Not very much, since Lambda-CDM doesn't make too many assumptions about galactic formation.

Lots of interesting implications for galaxy formation.
 


Thank you both for your comments, they are appreciated.
 


Grep said:
Just read an article on Universe Today at:

http://www.universetoday.com/77662/missing-milky-way-dark-matter/

The paper is at http://arxiv.org/PS_cache/arxiv/pdf/1011/1011.1289v1.pdf .

It introduces what seems to be rather tight constraints on the dark disc. Any cosmologists care to comment on it? What effect might this have on the Lambda-CDM model, for example? I'm somewhat surprised at these results.

At least someone is surprised, certainly a whole lot of people in this forum should be very surprised at these results, it's kind of weird that the diehard supporters of the dark matter hypothesis don't show up here to bash the paper, probably they can't and therefore choose to ignore it.
IMHO there should be more work in this direction to confirm it, and if indeed it is confirmed it is a serious indication that the hypothesis of dark matter (and MOND) should be abandoned.
twofish-quant said:
Really interesting.
Lots of interesting implications for galaxy formation.
Indeed, I agree.

twofish-quant said:
Not very much, since Lambda-CDM doesn't make too many assumptions about galactic formation.
This is not true or misleading at best. L-CDM makes strong assumptions about galactic formation. In fact without the dark matter assumption galaxies couldn't form at all within the L-CDM model.Simply quoting from the link of the OP :"The current understanding is that dark matter helped form the first galaxies by providing gravitational scaffolding in the early universe".
A different thing is that the L-CDM model doesn't enter on the actual details of galaxy formation. That much is true.
 


This paper seems interesting but there doesn't seem to be enough to make some analysis.
Obvious question that comes to my mind. If there is no significant effect of dark matter at 2-4kpc then at what distance effect of dark matter is significant and how it changes if it does that?
Then it would be possible to make some speculations about dark matter profile within galaxy.
 


TrickyDicky said:
At least someone is surprised, certainly a whole lot of people in this forum should be very surprised at these results, it's kind of weird that the diehard supporters of the dark matter hypothesis don't show up here to bash the paper, probably they can't and therefore choose to ignore it.

Just a question: isn't the disk supposed to contain only a very small portion of the total dark matter halo of our Galaxy?

If so, I do not see why this places constraints on the dark matter hypothesis; perhaps just on the thickness and density of the portion in the disk, values which are uncertain at best.
 


Dark matter is generally believed to be distributed uniformly around the galaxy in a halo, not a disc. The shape of the milky way is believed to be due to a spherical wave. Dark matter is not similarily influenced. In other words, there is no evidence suggesting dark matter distribution must mimic the shape of the milky way.