(read more @ BBC) Please Register or Log in to view the hidden image! So, what are your thoughts, what really is dark matter? Or maybe that is a galaxy where all stars have "died"?
Hum, it should be noted that two passing hydrogen clouds, moving in opposite directions, would give the illusion of a huge gas cloud rotating; and that in turn would eliminate the need for any dark matter to hold them together. (er, not that i believe that)
Well.. can it be ruled out somehow? (I mean , with physical evidence). p.s. I see that my question about dark matter is incorrect. It can be many things together.
Hum, i suppose that they could try to map out the cloud with a bit more precision so that any spatial difference would show up... Or they could look out for a (unproven) gamma ray signature emitted by the interaction of dark matter and this cloud... But here is the link to the Cardiff uni guys site... http://www.astro.cf.ac.uk/groups/galaxies/latestnews.html
I thought that dark galaxies were detected before (in 2003 concretely) http://www.newscientist.com/article.ns?id=dn4272 How come the investigators forgot that?
@Lucas Hum, i wasn’t aware of that discovery either. And as far as i can see it hasn’t been retracted. I can only assume that some doubts arose afterwards that may have influence the newscientist guys, er, or they got it wrong (it has been known) But, nice work.
Anybody else find that picture amusing? I mean you've got an astronomy photograph showing a black background and the usual white dots - and there's a big oval on it, and it's like, "There's this amazing galaxy that you can't see! Right there! Can you see it? NO! Isn't science wonderful?" I still can't find out if there's a consensus that dark matter is simply stuff like rocks and gas that isn't hot enough to radiate, or some other unknown form of matter.
Hum, Yeah, funny... (<i>Cosmologists, in general, are a funny lot</i>) The consensus is that dark matter isn’t matter (as in everyday baryonic stuff like tables and chairs). If what we see is correct (<i>the rotations of galaxies are too fast and need `extra mass/dark matter` etc</i>) and it’s not an unknown feature of the way gravity interacts in our universe (<i>non inverse square</i>) then there are a few contenders currently being searched for that would supply that `extra mass`. One theory is that it's composed of theoretical subatomic particles called Weakly Interacting Massive Particles (<b>WIMPS</b>). If Wimps exist, they would fill the spaces between the stars, and would interact with normal matter so weakly that they would pass right the way through the Earth. The wimps Dama (DArk MAtter) experiment, at the underground Gran Sasso facility in Italy, is one of several around the world hoping to spot the tell-tale signs of rare collisions between Wimps and ordinary atoms. Wimp candidates include the existence of a whole host of previously unrecognised subatomic particle (<b>acceleron</b>, <b>neutralino</b>, <b>photinos</b>, etc) Others have proposed an esoteric second-generation scalar field, known as <b>k-essence</b>, as an explanation for dark energy/dark matter. And I’m sure that there are a lot more to come... It’s all debatable. But, one thing is for sure, only 5% at most, of the Universe is made up of "normal", baryonic matter.
Even if the suspected pseudo-galaxy consists mostly of dark matter, how do we know that it contains no stars at all? There could be a scattered population of very small main-sequence stars and brown dwarfsm, which don't produce enough light overall to show up against the ambient sky brightness. This may be a very young galaxy, where star formation has barely begun (or, for some reason, never did begin) - or, who knows, an extrme low surface brightness galaxy, old enough for all the really luminous stars to have died.
Hum, yeah, A case of journalistic licence... at 50 million light years away, any heat signature would be too faint to say either way. But it gives a upper limit on any that may be present.
Do you suppose that some proto-galactic gas clouds, just as old as our own Milky Way, could have been so dynamically stable that they never collapsed sufficiently for star formation to begin? Those could be called dark-matter galaxies, but we'd have to mean dark baryonic matter.
Yeah, I believe that there should be a lot out there, waiting to be discovered. There is a huge amount of normal matter that is still unaccounted for, when we work out the photon density balance with the atoms per unit of space, and with what we know about the Big bang. I believe that the Chandra X-ray Observatory found two huge intergalactic clouds quite recently. And it is proposed that a vast `<b>cosmic web</b>` of hot gas pervades deep space. <font color=blue> < update > </font> "<i>An inventory of all the baryons in stars and gas inside and outside of galaxies accounts for just over half the baryons that existed shortly after the Big Bang</i>." “<i>These clouds have defied detection because of their extremely low density and temperature range of a few hundred thousand to a million degrees Celsius. Evidence for this warm-hot intergalactic matter (<b>WHIM</b>) had already been detected around our Local Group of galaxies, but the lack of definitive evidence for WHIM outside our immediate cosmic neighbourhood made any estimates of the universal mass-density of baryons unreliable.</i>” http://researchnews.osu.edu/archive/foundmat.htm <font color=blue> < /update > </font>
Hum, i`m not sure about plasma theory (i havent read up on it) Your link is not working btw. Anyway the case of the missing normal baryonic matter seems to have been solved. As for `dark matter` well thats still a big unknown and another thread...
haha.,the guy who did that helped me with one of my projects,nice guy and he knows his shiznit.good beard.i could ask him questions and get a reply if you wanted to know anything specific.
