Dark Matter Found

cosmo_uk · Post by **cosmo_uk** » Tue Aug 22, 2006 10:32 am

Check this out. Direct evidence for Dark Matter which rules out modified gravitation.

http://xxx.soton.ac.uk/ps/astro-ph/0608407

http://xxx.soton.ac.uk/pdf/astro-ph/0608407 is the pdf version

Cosmo

astro_uk · Post by **astro_uk** » Tue Aug 22, 2006 10:51 am

For those that want a more simplified view check out the BBC story or the Washington Post one

http://news.bbc.co.uk/1/hi/sci/tech/5272226.stm
http://www.washingtonpost.com/wp-dyn/co ... 01139.html

but the one cosmo linked too has some very pretty figures.

HoyleMan · Post by **HoyleMan** » Tue Aug 22, 2006 11:09 am

OK so theyre saying that the offset between where hot gas is and where the mass is is evidence for dark matter.

isnt it more likely that they just pointed each telescope in a slightly different direction (by accident!) and found these results!

astro_uk · Post by **astro_uk** » Tue Aug 22, 2006 11:23 am

Er no,

the offset they see is a very significant distance on the sky, of the order of 6-7 arcseconds, the pointing error on observations such as these is usually lt 0.1 arcsecs. Plus if you look at figure 1 in the paper you can see that the green contours (the galaxies, or luminous matter) are more widely separated in than the gas blobs (red areas). There is no way that you can move one set of observations to line up with the other, if you move the green contours so that the large cluster now overlaps the bigger red blob, the smaller cluster is now much further from the second red blob.

iamlucky13 · Post by **iamlucky13** » Tue Aug 22, 2006 7:53 pm

Minor correction...at least as far as I understand the press release I read...this doesn't rule out modified gravity, but the results of this observation can not be explained by modified gravity, or anything else currently on the table, making it extremely strong support that dark matter rather than modified gravity is responsible for the structure of the galaxies.

Anyway, is this even relevant...I haven't seen a picture of this so-called "dark matter" on APOD yet.

astro_uk · Post by **astro_uk** » Wed Aug 23, 2006 9:01 am

Little on here is really on topic fortunately, otherwise all we would be discussing is cloud formations and smoke trails of late. Sigh.

Anyway there are several APODS of DM including this nice one.
http://apod.nasa.gov/apod/ap030814.html