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Dark Matter Stars in the Early Universe?
OriginalArlen writes "UniverseToday reports new research which suggests dark matter could have condensed to form 'dark stars' in the early universe. These stars would have been very massive and burned very slowly, fueled by non-fusion reactions, they could still be with us. Astronomers hope to better constrain theories of early galaxy and star formation with observations of gravitational lensing events caused by these ghosts of the primordial universe."
What makes normal matter collapse is the "friction" or "interaction" between the charged particles. Dark matter is neutral as far as we know and it does not interact through the EM-forces. Hence the name "dark," meaning it does not interact with light either. It is hard to form models where dark matter "collapses". The reason is that the dark matter particles do not exchange energy/momentum easily, as they interact through the "weak" forces only.
This aspect of dark matter has always been troubling. If dark matter reacts gravitationally with ordinary matter, shouldn't we find the two combined within some sort of object? Everyone talks about how dark matter explains galactic rotation and cluster movement, but no one seems to say anything about what happens when you mix them. Why wouldn't dark matter collapse into a stellar interior along with the ordinary matter? How would this affect the nuclear processes within the star?
Why would there be "stars" made entirely of dark matter, anyway? What keeps ordinary matter from falling in?
As matter clouds condenses, gravitational energy is released. This energy has to be radiated away for the collapse to proceed, as the collapse is opposed by the thermal kinetic energy of the matter in the cloud. This was a major problem in the early universe when the abundance of metals was so low that radiation cooling was less efficient. If dark matter interacts very weakly with normal matter and electromagnetic fields, cooling is going to be very slow indeed. We know that dark matter exists and that it forms concentrations on the scale of large galaxies. We do not have strong evidence for the concentration of dark matter in the solar system, where it could result in apparent radial variations in solar or planetary masses. I supect that cooling of stellar mass dark matter clouds is rather difficult. Once somebody figures out how to observe the stuff and its properties, we can better understand what we see and what we should be looking for.
A sufficiently advanced civilization that doesn't destroy itself first will inevitably optimize their environment to the point of harvesting every last drop of energy from their star(s), such that we can't detect anything but the gravitational effects.
This mysterious "dark matter" structure is termed a Matrioshka Brain (aka: Dyson Sphere).
I understand that this theory's still a bit too shocking for many to seriously consider, so "exotic particles" - or ANY other explaination - it must surely be.
Power to the Peaceful
Does it seem weird to anyone else? Now I haven't stayed up to date with dark matter, but they keep insisting that it MUST be there. It almost seems to be the ether that was claimed to be around us before Einstein blew that one open.