[/caption]
The first stars to light the early universe may have been powered by dark matter, according to a new study. Researchers from the University of Michigan, Ann Arbor call these very first stars “Dark Stars,” and propose that dark matter heating provided the energy for these stars instead of fusion. The researchers propose that with a high concentration of dark matter in the early Universe, the theoretical particles called Weakly Interacting Massive Particles(WIMPs), collected inside the first stars and annihilated themselves to produce a heat source to power the stars. “We studied the behavior of WIMPs in the first stars,” said Katherine Freese and her team in their paper, “and found that they can radically alter the stellar evolution. The annihilation products of the dark matter inside the star can be trapped and deposit enough energy to heat the star and prevent it from further collapse.”
The philosophy behind this research is that 95% of the mass in galaxies and clusters of galaxies is in the form of an unknown type of matter and energy. The researchers say, “The first stars to form in the universe are a natural place to look for significant amounts of dark matter annihilation, because they form at the right place and the right time. They form at high redshifts, when the universe was still substantially denser than it is today, and at the high density centers of dark matter haloes.”
The concentration of dark matter at that time would have been extremely high meaning that any ordinary stars would naturally contain large amounts of dark matter.
Dark stars would have been driven by the annihilation of dark matter particles releasing heat but only in stars larger than 400 solar masses. That turns out to be quite feasible since stars containing smaller amounts of dark matter would naturally grow as they swept up dark matter from nearby space.
The stars continued, and may still continue to be powered by dark matter annihilation as long as there is dark matter for fuel. When the dark matter runs out, they simply collapse to form black holes.
If they exist, Dark Stars should be able to be detected with future telescopes, and if found, would enable the study of WIMPs, and therefore be able to prove the existence of dark matter.
Sources: arXiv, arXiv blog
“95% of the mass in galaxies and clusters of galaxies is in the form of an unknown type matter, dark matter.”
Errr – isn’t it that 5% of the total energy is regular fermionic particles as we know them? The remaining 95% is both DM and Dark Energy.
If this be true, the next questions are “did the process stop?” and “why?”
What confuses me is the notion that these dark matter particles are being annihilated. What is causing the annihilation? Using the word annihilation conjures up notions of matter to energy conversion, so whats the process going on here? I was under the impression that we dont even know what dark matter even is, WIMPS’ are just a current best guess…
“We studied the behavior of WIMPs in the first stars,” said Katherine Freese and her team in their paper, “and found that they can radically alter the stellar evolution.
yea right.. more theoretical experiments on theoretical particles with theoretical explanations on the results
Am I the only person to whom this research seems unsettling, or perhaps straddling the border line between art and science?
Isn’t “Dark Matter” simply a word for something we don’t know what it actually consists of? And “Wimps”, I learned, are a thought model, an aid for being able to do calculations, without the need to know more.
What sort of stuff annihilates itself, just like that? Scary, if annihilation can happen just like that,,,,
Fascinating speculative work, a great read, enjoyable, entertaining, and thought-provoking… really showing off our place in the “scheme of things” on a cosmic scale…. but can I relate to it as “science”?
Quote: “The _philosophy_ behind this research is…”
Have the development of science and philosophy completed a full circle since antiquity, and are they converging again?
As questionable as some of the statements in this research are, I always enjoy reading about dark matter – just as I enjoy reading science fiction stories.
And about “The _philosophy_ behind this research is…”: As far as I can tell, most of the time, when someone says this, it has nothing, really nothing, to do with philosophy in the original sense. It’s just a saying, the trivial meaning of which may be “someone started making the following assumptions …”. People should not use the term “philosophy” in such a case, but there is no chance of changing this, i think.
Hmm . . . I’ve always thought that the ‘big bang’ maybe wasn’t so big. That space, time, energy and matter appearing in an instant from nothing defies logic. I believe E=MC2 sez it all. There simply had to be some form of unknown energy from which all matter morphed from and may still be in progress on a scale we haven’t yet detected. Why couldn’t the dark energy we think is out there be the source of all we can see and maybe beyond?
Makes me wonder what kind of black hole a Dark Matter fuelled star would create… and then I pass out due to the complexity of it all 🙂 .
G:
The WIMPs are believed to be their own antiparticles, like neutrinos and photons, wich means that if 2 of them gets to close they annihilate eahother. In high concentration areas then more annihilation would occur than in sparse areas.
Whether WIMPs exist or not remains to be seen.
Some time, black holes were also theroretical since no one has seen one yet, now we see them everywhere.
Some time ago other planets were theoretical, now we see them everywhere.
At this point the highs particle is still theoretical, but soon we migth be able to confirm it’s existance or not with the LHC.
At this point additional dimensions are theoretical but with any luck and the LHC we might confirm it’s existance or not.
And so far I now, the properties of dark matter are very well known, it is just that up untill now we have no confirmation about its existance so time and many experiments will tell.
Wouldn’t the more obvious star fueling annihilation reaction have come from regular matter with regular anti-matter – assuming that almost equal amounts of each were produced in the big bang?
Perhaps not. Matter and anti-matter would annihilate each other before being able to gravitate together to form a star. But then wouldn’t dark matter do the same?
Or perhaps, if we endow this imaginary stuff (dark matter) with the properties of weakly interacting only through gravity and interacting even more weakly in the self-annihilation reaction, then we can get it to do exactly what we imagine it should have done.
Ow – I just broke my brain.
If given enough time I think they’ll either come up with an explanation for the acceleration of the universe or find out they were wrong in total. But It seems Dark Matter is overly generalized to encompass all aspects of cosmology. “Too much bang with no proof is all I’m saying”.
@Olaf:
“And so far I now, the properties of dark matter are very well known, it is just that up untill now we have no confirmation about its existance so time and many experiments will tell.”
For me it looks like dark matter first has been _defined_ by physicists as only having gravitational interaction with other matter (no electro-magnetic interaction, therefore “dark”). Now there are some theories assuming – yes: “theories” and “assuming” (by the way the normal procedure in physics) – some more properties.
One assumption is, that dark matter can do matter/anti-matter annihilation. This is an interaction through the strong nuclear force, as far as I know (somebody may correct me). But until now nobody _knows_ the properties of dark matter (not speaking of “very well known”).
And does dark matter exist? Well, some may say, e.g.: we observe the movement of stars in galaxies and of galaxies in galaxy clusters, and there must be some mass somewhere in order to explain the movement we observe, and we can _not_ _see_ normal matter contributing to this mass, ergo: dark matter (along the line of the definition above) exists.
Such utter total BS, I hardly know where to start….
“yea right.. more theoretical experiments on theoretical particles with theoretical explanations on the results”
And how, pray tell, does one falsify the concept of WIMPs, if one does not calculate the consequences of their comprising DM?
@Sili:
“And how … does one falsify the concept of WIMPs, if one does not calculate the consequences of their comprising DM?”
It’s simple logic. If one does not calculate the consequences, one is not able to falsify the concept. Considerations of this kind should not be presented to the public as scientific research, at best as science fiction – which can be amazing.
I knew several wimps in high school who were regularly annihilated by big bangs.
Space is big, so big that, like many other commenters, it hurts my head. The growth of knowledge in astronomy, has been, pardon the expression, astronomical. I didn’t believe at first that there was so much “stuff” out there and our total means of learning about it is to “see” it. (includes all forms of detectable radiation~ therein lies the rub, what we see doesn’t behave the way it should if what we see were all there is.). From that very limited input, astronomers have given shape and form to what we know about the universe. Human knowledge requires understanding and questioning everything we think we know. That’s why it’s called science (i.e. “knowing”).
It was only in the 1930’s that the concept of a galaxy was put forth as an idea and now it is the accepted norm. We have seen pictures all over the internet that would have rocked the world of the astronomers of less than 100 years ago.
I take the ideas of dark matter and dark energy and WIMPs as useful working models that will allow today’s astronomers and other scientists to develop further what has come to be known about everything else in the universe. Will we ever really finish learning? Probably not.
Olaf said that there were several ideas that either have been or soon will be proven, so why not dark matter (DM). While I agree that much in science starts out as an unproven idea, sometimes very outlandish seeming ideas, there is usually some sort of support for the idea. Take black holes or exo-planets. Einstein’s math was pretty solid and subsequent work by others only reinforced the work when it came to black holes. The theory behind black holes was so good that it was more of a search for the right telescope rather than for the object. As for exo-planets, I think the fact that we stand on a planet was pretty convincing evidence that there was a high probability of other stars having planets too. Again, more of a telescope search than anything else. The math indicating that there is a Higgs particle appears to be solid. The math indicating other dimensions is less conclusive, but appears often enough in string theory and has a measure of robustness that one can be forgiven if a person believed that the search is primarily for the right instrument.
When it comes to DM, I think the issue is less clear. Yes, there does appear to be a large source of gravity out there that we can not account for yet, at least on very large scales. Since we can not see it, it makes sense to call it DM. Whatever it is, be it matter or energy, about the only thing we know for sure about it is that it exerts and is affected by gravity. I think that Olaf confuses the above examples that were/are on firm ground with DM which is on much more shaky ground.
That is not to say that those doing the research shouldn’t be stretching themselves and pushing the limits of their intellects and imaginations. They should. Perhaps papers such as the article talks about can serve an important function as thought experiments. Remember, Einstein never conducted a single experiment. The problem with research into DM that I see is this. The field is very important and very high visibility. I would be willing to bet a lot of money that whoever definitively proves what DM is will be guaranteed a Nobel prize. So the stakes are high. I expect we will see a high noise to signal ratio when it comes to DM papers and that will make it difficult to cull out the helpful thought experiments from the chaff. I don’t think that improper comparisons help with the winnowing process.
On a different point, the idea that DM is its own anti-particle seems like a rube goldberg contrivance. Given the amount and densities that we think we are seeing now, then there must have been a unbelievably huge quantity of the stuff in the early universe. That would imply very different conditions than appeared to have existed. Just think of the resulting gravity, heat, and mass through which other particles would have to move. It makes sense that DM has an anti-particle, but it defies logic that it is its own. Of course, the universe has a way of surprising us just about every day.
This space cointains many white tiny light particles, glowing & are moving & keotic movement lkike jumping in any direction.
A couple of questions that pop to mind are:
1) How would the dark matter have been condensed into the appropriate concentrations in early stars?
2) What would have propped up the dark matter from gravitational collapse into black holes long enough for them to annihilate?
Interesting, but…….I’m w/ Feenixx. I find it hard to assume DM (aka WIMPS) are their own annihlation partners. Sort of a big assumption; ie., if everyone in the world were nice…
“What would have propped up the dark matter from gravitational collapse into black holes long enough for them to annihilate?”
Good question. Astrophysicists say, that most of the time stars built out of normal matter are in an equilibrium between gravity – which tries to compress the star – and radiation pressure – which tries to expand the star. Dark matter, by definition, does not react to radiation (electro-magnetic interaction). So what does the dark matter inside a star – where these particles are near to each other already – keep from collapsing more and more rather rapidly?
A similar question comes to mind: What does a neutron star keep from collapsing? As far as I know, electro-magnetic interaction is not needed for the stability of a neutron star. I have read something about “configuration pressure”, which has to do with quantum physics.
“buster” is correct. it’s unreasonable to base a new theory on top of an other unproven theory. it is fun to imagine though and makes for a good read.
The statement written above on Jan’4th 2009 at 4.42am is not a comment. it is real & can be seen.
in response to Yoo
1) How would the dark matter have been condensed into the appropriate concentrations in early stars?
2) What would have propped up the dark matter from gravitational collapse into black holes long enough for them to annihilate?
it’s obvious. dark energy????
Dark Matter – existance proven but unkown
WIMPs – unproven existance
These are the basis of their statements?
How are we to believe these conclusions??
I don’t know if there is a direct link between dark matter and dark energy. I thought these were completely different things and had nothing in common with that fact that it is unknown.
God i feel real stupid about asking anything about physiscs. Please bear with me?!?
If a ball is put in a spin in space it will spin forever right. But the law of physics says for every action there is an equal and opposite reaction. What is the reaction in this case? Black matter?
“God i feel real stupid about asking anything about physiscs. Please bear with me?!?”
No problem. Asking questions is a sign of intelligence in many cases.
“If a ball is put in a spin in space it will spin forever right. But the law of physics says for every action there is an equal and opposite reaction. What is the reaction in this case? Black matter?”
As long as you are on the way to “put” the ball in a spin, you exert a force on the ball, increasing its torque. The inert mass of the ball _re-acts_ with a force against your force. Have you ever accelerated a merry-go-round with children on it? You can _feel_ the resistant force of the mass of the apparatus plus the children.
After having stopped exerting the force on the ball – and assuming there are not _other_ influences (e.g. from gravitation) –, the ball remains in its current state, i.e. spins forever. This is a basic principle of classical physics, invented (some say: discovered) by Isaac Newton.
In modern physics, of course, it’s a little bit different. After certain periods of time there will be some radioactive decay of some elementary particles in the ball, and there will be some quantum fluctuations too. This will change the torque of the ball a little bit.
I don’t like this theory, there are to many if’s.
1> what is dark matter? No one knows!
2> what is dark energy? No one knows!
3>If dark energy and dark matter exist where did it come from?
4> If the first stars were made from dark matter, did these stars create normal matter?
5> If stars created from dark matter exist, can can you tell the difference from stars that are created from normal matter?
Ronald White