Dark matter and dwarf galaxy Segue 1

[Geoff]

Interesting article about one of the milky way's dwarfs and dark matter research. New Scientist may also have this on their site.

http://www.physorg.com/news140959932.html

[Edd]

Not so obvious from the article, but SEGUE is part of SDSS-II, and given the name is 'Segue 1' I imagine there's a pretty strong link

[graham d]

Yes- Josh Simon mentioned Segue 1 in a videao link posted a couple of months ago. It's a newly discovered low luminosity dwarf towards the centraal bulge of the galaxy. The number of these dwarfs has now ca. doubled, a consequence of the SDSS survey. His was the first reference I came across for the 1000/1 ratio of CDM/dark matter, although I see that Geha is quoting a varied ratio of 100/1 to 1000/1. The hunt for Machos hasn't proved fruitful or significant.
It would be nice to get some distance data and polar coords for these dwarfs, since one might expect the ratios to be much higher within the CDM shell.

[Adrianus V]

I've read the news about Segue 1. I'm curious about one thing. More than a year ago there was the same kind of news: in Virgo scientists had seen a completely invisible galaxy, which was made completely out of dark matter. It's called VIRGOHI21. What's the comparison between Segue 1 and VIRGOHI21? The last DM-galaxy might have a mass of 100 billion solar masses, much larger that the estimated mass of Segue 1. 

[graham d]

Joseph Cheng posted -
587738568703410192
as object of the year back in July last year. It's NGC 4254- google for info.
If you zoom out until two other galaxies, one a ringed galaxy, come into view. Toggle the zoom until it ca. matches this next link for VirgoHI 21.
http://www.naic.edu/~rminchin/virgohi21.html

Wow!

[Thomas J]

What an interesting find and a great area for research.

Do you think this could help to explain the missing dwarf satellite galaxies throughout the Universe?

[Pat]

And could possibly cause lenses without seeing a central galaxy?

[Adrianus V]

And could possibly cause lenses without seeing a central galaxy?

Mmmm, interesting thing. In that case you see arcs, without any galaxy. Maybe worth for looking into the SDSS-data for this phenomenon.  Just single arcs. Or in the most extreme form: an Einsteinring around a dark galaxy! 

[Thomas J]

I think there is huge scope, here, for some very interesting study.

[Adrianus V]

I think there is huge scope, here, for some very interesting study.

Maybe it's worth a seperate thread.

[jules]

I think there is huge scope, here, for some very interesting study.

And a very interesting study for a huge scope.
(sorry!)

[Thomas J]

I think there is huge scope, here, for some very interesting study.

And a very interesting study for a huge scope.
(sorry!)

Interesting, huge scope for study

[Thomas J]

I think there is huge scope, here, for some very interesting study.

Maybe it's worth a seperate thread.

Agreed.

[Adrianus V]

I think there is huge scope, here, for some very interesting study.

And a very interesting study for a huge scope.
(sorry!)

I just started a new topic about this.  

[EdV]

I've always wondered why we don't see other dwarf galaxies in SDSS...