Dark matter properties detected using VLT

[Chronos]

A recent study using the VLT array has measured the temperature and size of dark matter clumps. Interestingly enough, the study has not yet been submitted to Arxiv, but will probably appear within a week. It is expected to be one of the most important papers in 2006. Here is a teaser:

Dark matter comes out of the cold
http://news.bbc.co.uk/2/hi/science/nature/4679220.stm

[marcus]

A recent study using the VLT array has measured the temperature and size of dark matter clumps. Interestingly enough, the study has not yet been submitted to Arxiv, but will probably appear within a week. It is expected to be one of the most important papers in 2006. Here is a teaser:

Dark matter comes out of the cold
http://news.bbc.co.uk/2/hi/science/nature/4679220.stm

We talked about that BBC article "Dark matter comes out of the cold" in another PF thread started 2 or 3 weeks ago
http://www.physicsforums.com/showthread.php?t=109870

About Arxiv, I think the study may already have been submitted to Arxiv actually.
Gilmore is one of the authors

http://arxiv.org/abs/astro-ph/0602186

this was posted on Arxiv around 8 February which was about the same time that the "out of the cold" BBC article quoting Gilmore was posted.

I have a vague memory of discussing this with Spacetiger, a couple of weeks ago, and maybe you also were in that thread. It was about the BBC article you mention.

The thing was they inferred that the DM particles were going around 9 kilometers per second, because they didnt find clouds smaller than a certain size, and the size of the clouds was inferred from the clumps of VISIBLE matter-----the dwarf galaxies

dont completely remember, may be mistaken

[marcus]

Some interesting points came up in that earlier discussion of the BBC article you mentioned

You may recall it now. This is how it started----topic was 'temperature of DM'
http://www.physicsforums.com/showthread.php?t=109870

http://news.bbc.co.uk/1/hi/sci/tech/4679220.stm

Gerry Gilmore's Cambridge team did a survey of clouds of dark matter, using several telescopes including VLT in Chile. they found no blobs of DM smaller than about 30 million solar masses, or less than 1000 lightyear diameter.

They inferred from this a characteristic TEMPERATURE of dark matter. the particles must be moving on average 9 kilometer per second, so that clouds that are not big enough DISPERSE by random motion.

The clouds that are not big enough don't have enough gravity to hold themselves together, given the particles' speed of random motion.

Spacetiger had some things to say, I think you also commented, and several other people

[Chronos]

Oops. I need to replace my memory chips.

[marcus]

Oops. I need to replace my memory chips.

when you find a supplier, let me know----I could use some too:smile:

[Chronos]

I'm too excited to sleep until I see the paper . . . zzzzzz.