Galaxies Protected by Dark matter

[xXTheOneRavenXx]

http://www.space.com/scienceastronomy/0 ... atter.html

Could this new discovery of these dwarf galaxies not being affected while the larger surrounding galaxies are being ripped apart also indicate that not only the dark matter in the dwarf's is of more abundance, but also have a greater density as well? Or purhaps it could also mean that these dwarf galaxies have a black hole that has a greater impact on it's surrounding stars then what the black holes that may lerk in the centre's of the larger galaxies do. Being larger also means that the outer edge stars are further away from their black holes, purhaps making them more subsepible to being pulled away from their host galaxies. I'm all one for the existance of Dark Matter without a doubt, but a constructive objection comes to mind. I'm not too sure the following statement could suggest the higher dark matter content without also taking into consideration the black hole factor as well. What are your thoughts?

"The dwarf galaxies may have even higher amounts of dark matter than spiral galaxies like our Milky Way.
"With these results, we cannot say whether the dark-matter content of the dwarfs is higher than in the Milky Way Galaxy," Conselice said. "Although, the fact that spiral galaxies are destroyed in clusters, while the dwarfs are not, suggests that is indeed the case."

 

[MeteorWayne]

Interesting, I just read about the "Leo Ring" a number of dwarf galaxies that appear to have little or no dark matter at all.

 

[xXTheOneRavenXx]

Good to see you again MeteorWayne

That would be interesting to read as well. Purhaps if the Leo Ring galaxies have similar size black holes as these dwarf's do, then maybe the data collected on the size, shape and density of these two groups of dwarf galaxies may be the key to finding out how much of an impact is caused by the Dark matter, and how much is natural to their host black holes.

 

[MeteorWayne]

Good to see you again MeteorWayne

That would be interesting to read as well. Purhaps if the Leo Ring galaxies have similar size black holes as these dwarf's do, then maybe the data collected on the size, shape and density of these two groups of dwarf galaxies may be the key to finding out how much of an impact is caused by the Dark matter, and how much is natural to their host black holes.

I'll dig it out. It was in a recent Science or Nature magazine...

 

[BoJangles2]

Indeed interesting, a link to the article or research would be great, dark matter always interests me

 

[xXTheOneRavenXx]

The unknown... exactly why I'm glad to be back

 

[derekmcd]

Interesting, I just read about the "Leo Ring" a number of dwarf galaxies that appear to have little or no dark matter at all.

Interesting here as well. I read about the Leo Ring after (it may have been 'before'... I honestly don't remember. However, I did conclude the observations of dwarf galaxies had some rather extreme conclusion on dark matter). Here is the paper actually being discussed:

http://arxiv.org/abs/0811.3197

When I have time, I will re-read both papers and try to discern the difference. My success rate is improving, but I guarantee nothing.

 

[xXTheOneRavenXx]

Every time I see a video on Dark Matter it depicts it as a vast interconnected web that seems to connect many galaxies across the universe. If this is true could it be proven that along this "web" there could be a higher concentration of Dark Matter without the need for normal matter to exist in that area? (ie finding a high concentration of Dark Matter within a void of normal matter) or on the other hand does both Dark Matter and normal matter both exist within the Lyman Alpha Blobs during galactic formation? If Dark Matter does exist in the ones we see today, then what would cause some galaxies not to have a presence of Dark Matter?

 

[MeteorWayne]

From what I've read, what you describe does exist. The wide field observations needed to confirm that are only a few years old, such as the Sloan Digital Sky Survey. PANSTARRS, which will soon go online will also create a boatload of new data.

 

[xXTheOneRavenXx]

I had one more question. In these dwarf galaxies is it known if the black holes in their centers are the same size as the ones contained within the larger ones? Or if they are equal in proportion to their size? That would also be quite interesting to find out.

 

[MeteorWayne]

I had one more question. In these dwarf galaxies is it known if the black holes in their centers are the same size as the ones contained within the larger ones? Or if they are equal in proportion to their size? That would also be quite interesting to find out.

AFAIK, no black holes have been confirmed at the centers of dwarf galaxies, but I'll have to check on that. Perhaps that is a major difference between galaxies and dwarf galaxies?

 

[xXTheOneRavenXx]

The best definition of a dwarf galaxy I found was from wikipedia:

A dwarf galaxy is a small galaxy composed of up to several billion stars, a small number compared to our own Milky Way's 200-400 billion stars. The Large Magellanic Cloud, containing over 30 billion stars, is sometimes classified as a dwarf galaxy while others consider it a full-fledged galaxy going around the Milky Way galaxy. Current theory believes most galaxies, including dwarf galaxies, form in association with dark matter or out of gas containing metals. However, NASA's Galaxy Evolution Explorer space probe identified new dwarf galaxies forming out of gases lacking metals. These galaxies were located in the Leo Ring, a cloud of hydrogen and helium around two massive galaxies in the constellation Leo.

But it doesn't mention anything about whether or not they have black holes. I would think if they do they'd be easier to spot interacting with surrounding matter by the galactic center being more visible with less stars and gas.