|MadSci Network: Astronomy|
That is one loaded question! How to answer? I suppose that it would depend upon what you mean (and the scientists in the article mean) by both "dark matter" and "vibrational energy". So, let's begin with a little cosmology. NASA's Wilkinson Microwave Anisotropy Probe has mapped out the microwave background of the visible Universe. The results of this detailed map tell us that the Universe consists of 4% matter, 23% dark matter, and 73% dark energy. This means that everything that we can see - all of the atoms in all of the stars throughout the Universe - amounts to only 4% of the 27% of the Universe that is "normal" matter. I put normal in quotes because it may or may not be the baryonic matter that is around us. But if it is, then dark matter is just the stuff of the Universe that isn't shining. And there are a lot of candidates - such as Massive Compact Halo Objects (MACHOs). These are things like the remnants of stars or red dwarfs or large planets and since they consist of ordinary matter under ordinary conditions, the presumption would be that they would behave in a manner consistent with the laws of physics as we know them. Hence, they should possess "vibrational energy" - if by that, we mean energy associated with vibrational states. That is, they are not at absolute zero. Indeed, many of these objects - such as red dwarf - would have considerable vibrational energy as they are still "stars" and are emitting radiation, albeit very weakly. I could also add black holes to the list of MACHOs but I am not sure how I would classify black holes in terms of matter. Clearly, they have mass and are generated from stellar material - from baryons. But as a singularity, they have no dimensions and are not akin to other forms of matter. That aside, the question of whether or not they have vibrational energy is perplexing. Yes, they do radiate. And if by "vibrational energy" we mean temperature, then yes, they do have temperature (or, at least, there is a temperature that we can ascribe them). But if by "vibrational energy", you mean non-zero point vibrational modes, I doubt that they do. A black hole doesn't radiate in the infrared region of the spectrum (or, at least, no one has detected a black hole radiating in the infrared...) and it is difficult to see how they could. On the other hand, since the event horizon prevents us from peering in (or radiation from coming out), I am not sure that a black doesn't. So, if dark matter is "normal" matter that is simply not radiant, then it is likely to have vibrational energy. On the other hand, if has vibrational modes, they the lower energy end of the electromagnetic spectrum should be obscured. That is, the dark matter throughout the Universe should be absorbing low wavelength radiation and re-emitting it at even lower wavelengths. Since the new emission spectrum would be quite different from the absorption spectrum, this should be a way to look for dark matter. But this absorption/emission has yet to be observed. So, the dark matter may be either concentrated in MACHOs or a particle that is completely invisible to the electromagnetic spectrum in which case it would be hard to argue that it has "vibrational energy". That is, it a particle is non-interacting with electromagnetic radiation, then it can't very well be absorbing or emitting radiation. No absorption or emission - no temperature, no vibrations. I should point out that the Hubble space telescope has been used to explore the question of dark matter on many occasions. In one set of results, the astronomers did not "see" dark matter but rather they were able to map the consequences of dark matter and in so doing, demonstrate that it pervades a galactic cluster. That is, they were able to see the gravitational effects of dark matter without actually observing the dark matter itself. In another report, a distant red dwarf was observed after it had resulted in the gravitational lensing of light from a distant star. The position of the dwarf mark it as a MACHO and provides evidence for at least some of the dark matter in our galaxy to be made out of massive "normal" objects. But I guess the final answer to your question is, we don't really know what makes up the 23% of the Universe that is "dark matter" and until we do, we can't know what are its properties. Great question, though!
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