News of direct observation of dark galaxies.

[OnlyTellsTruths]

Dark galaxies (not directly related to dark matter for those wondering) appear to have been observed by astronomers in Chile.

http://phys.org/news/2012-07-dark-ga...-universe.html

Quote:

For the first time, dark galaxies — an early phase of galaxy formation, predicted by theory but unobserved until now — may have been spotted. These objects are essentially gas-rich galaxies without stars. Using ESO’s Very Large Telescope, an international team thinks they have detected these elusive objects by observing them glowing as they are illuminated by a quasar.

Dark galaxies are small, gas-rich galaxies in the early Universe that are very inefficient at forming stars. They are predicted by theories of galaxy formation and are thought to be the building blocks of today's bright, star-filled galaxies. Astronomers think that they may have fed large galaxies with much of the gas that later formed into the stars that exist today.

Because they are essentially devoid of stars, these dark galaxies don't emit much light, making them very hard to detect. For years astronomers have been trying to develop new techniques that could confirm the existence of these galaxies.

http://www.telegraph.co.uk/science/s...iscovered.html


Someone should perhaps edit the wiki and remove the word "hypothetical" or maybe it is a bit too soon:

http://en.wikipedia.org/wiki/Dark_galaxy

[not_so_new]

Pretty cool... thanks for posting this. I read things over there almost every day but this one slipped under my radar.

[DC]

Originally Posted by OnlyTellsTruths

Dark galaxies (not directly related to dark matter for those wondering) appear to have been observed by astronomers in Chile.

http://phys.org/news/2012-07-dark-ga...-universe.html



http://www.telegraph.co.uk/science/s...iscovered.html


Someone should perhaps edit the wiki and remove the word "hypothetical" or maybe it is a bit too soon:

http://en.wikipedia.org/wiki/Dark_galaxy

wiki says otherwise.

Quote:

composed of dark matter

whats correct now?

[OnlyTellsTruths]

Originally Posted by DC

wiki says otherwise.



whats correct now?

I assume you may be joking? Did you read the articles?

They are composed of gas.

Quote:

These objects are essentially gas-rich galaxies without stars.

Quote:

Dark galaxies are small, gas-rich galaxies in the early Universe that are very inefficient at forming stars.

Dark matter is in all galaxies, so obviously they contain dark matter as well, that's why I said not directly related to.... I did not say, or even imply, that they contain no dark matter. By "not directly related" I meant their name "Dark Galaxies". As far as I understand it, that name is not directly related to Dark Matter, they were named as such because they are hard to detect. I'll try and find where I read that.

Until then, here's the rest of the wiki paragraph, compare to your wiki quote:

http://en.wikipedia.org/wiki/Dark_galaxy#Structure

Quote:

Furthermore, dark galaxies are theoretically composed of hydrogen and dust. Some scientists support the idea that dark galaxies may contain stars. Yet the exact composition of dark galaxies is unknown because there is no conclusive way to spot them so far.

[OnlyTellsTruths]

Originally Posted by not_so_new

Pretty cool... thanks for posting this. I read things over there almost every day but this one slipped under my radar.

Thanks for your post, I thought it was interesting as well.

[MG1962]

Originally Posted by DC

wiki says otherwise.



whats correct now?

No they are just gas that has not begun star forming. If dark matter could be detected by reflected light, we would have discovered it a long time ago. What makes these galaxies extremely interesting is the chance to test the Population III theory.

[DC]

Originally Posted by OnlyTellsTruths

I assume you may be joking? Did you read the articles?

They are composed of gas.






Dark matter is in all galaxies, so obviously they contain dark matter as well, that's why I said not directly related to.... I did not say, or even imply, that they contain no dark matter. By "not directly related" I meant their name "Dark Galaxies". As far as I understand it, that name is not directly related to Dark Matter, they were named as such because they are hard to detect. I'll try and find where I read that.

Until then, here's the rest of the wiki paragraph, compare to your wiki quote:

http://en.wikipedia.org/wiki/Dark_galaxy#Structure

well i didnt make a claim, but the wiki link seems to contradict what you said.
here from your link to wiki.

Quote:

A dark galaxy is a hypothetical galaxy composed of dark matter.

[OnlyTellsTruths]

Originally Posted by DC

well i didnt make a claim, but the wiki link seems to contradict what you said.
here from your link to wiki.

Hmmmm, did you read my last post, I think I covered both the fact that I didn't make the claim, and that if I did, the wiki does not contradict it.

Originally Posted by OnlyTellsTruths

Until then, here's the rest of the wiki paragraph, compare to your wiki quote:

http://en.wikipedia.org/wiki/Dark_galaxy#Structure

Quote:

Dark galaxies are composed of dark matter. Furthermore, dark galaxies are theoretically composed of hydrogen and dust. Some scientists support the idea that dark galaxies may contain stars. Yet the exact composition of dark galaxies is unknown because there is no conclusive way to spot them so far.

I'm not sure why they lead like that.

Couldn't the link to our galaxy similarly say:

Quote:

The Milky Way galaxy is composed of dark matter. Furthermore, the Milky Way galaxy is composed of stars, black holes, a supermassive black hole, planets, moons, comets, and meteors!

(I'm sure I left something out...)


Again, as far as I understand it, the Dark Galaxies name is not directly related to Dark Matter, they were named as such because they are hard to detect.

That's why I opened the OP with that "not directly related to" aside in parenthesis.

If I am wrong, I stand corrected.

[OnlyTellsTruths]

I apologize for how I worded the OP. I wanted to talk about this interesting confirmation, not have an argument about the name.


To get back on track, I note that HE0109-3518 is not one of the "Potential dark galaxies" listed in the wiki. That's interesting.

I also notice that the wiki page says "This page was last modified on 11 July 2012 at 21:42.", but I do not particularly see any of the new information from the articles in the OP which was also on the 11th.

[Dancing David]

Originally Posted by DC

well i didnt make a claim, but the wiki link seems to contradict what you said.
here from your link to wiki.

No, this is a different usage of the term 'dark galaxy', they do not have stars fusing, so stars do not shine.

Words can have more than one usage and meaning.

[DC]

Originally Posted by Dancing David

No, this is a different usage of the term 'dark galaxy', they do not have stars fusing, so stars do not shine.

Words can have more than one usage and meaning.

aah thanks i think that clears it up. dark matter in the sence of matter that is dark

i was a bit confused there.

[MG1962]

Originally Posted by Dancing David

No, this is a different usage of the term 'dark galaxy', they do not have stars fusing, so stars do not shine.

Words can have more than one usage and meaning.

Which brings up the point when is a galaxy a galaxy. If we are observing large gravity bound gas clouds, I wonder what they observe in them to elevate their status to galaxies.

[xtifr]

Originally Posted by MG1962

Which brings up the point when is a galaxy a galaxy. If we are observing large gravity bound gas clouds, I wonder what they observe in them to elevate their status to galaxies.

Reification. We want a nice, orderly, Linnaean universe, and what we get is a messy one full of edge cases and hard-to-classify exceptions. It's really our fault for being so categorical.

[Dancing David]

Originally Posted by MG1962

Which brings up the point when is a galaxy a galaxy. If we are observing large gravity bound gas clouds, I wonder what they observe in them to elevate their status to galaxies.

Good point, formative proto galaxies?