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Attributes of Dark Matter

  1. Mar 17, 2013 #1
    If dark matter is real matter out there in space, it must be absorbing photons from adjacent stars and other bodies. Also, by definition, it is not emitting any radiation, so it must be inexorably heating up. Is this sustainable, or will it cause some sort of explosion or start the body on an emission path later. Or is there some other way in which it could be losing heat ?

    Another question on this matter. Has anyone established whether dark matter is actually emitting radiation but this is so weak that our detectors cannot “see” the emitting body.
  2. jcsd
  3. Mar 17, 2013 #2


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    Staff: Mentor

    Dark matter isn't "real matter". Calculations have shown that the amount of mass required to account for the discrepancies we see in galaxy rotations and other phenomena is extremely high. So high that there must be large amounts of dark matter around, and if light passing through dark matter were absorbed in any great amounts we would immediately see it as a dark spot against the background stars and galaxies. It's possible that dark matter absorbs and emits EM radiation, but with a cross section so low that we can't see it, but then it wouldn't be heating up.
  4. Mar 17, 2013 #3
    More specifically dark matter is considerably different than what is loosely termed "real" matter. Normal matter is called baryonic matter. Dark matter being considered as non baryonic. Dark matter is only known to interact with normal matter via the gravitational force. It is not known if it intrracts with the electromagnetic force. the wak nuclear or the strong nuclear force. Its considered as weakly interactive due to the above.
    As its so weakly interactive it is also difficult to detect.
    Locations of dark matter has been mapped via its effect on gravity,
    Needless to say there is alot we don't know about dark matter.
  5. Mar 18, 2013 #4


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    Nope. Photon absorption only happens if the matter is made out of charged particles. As long as dark matter has no electric charge (and isn't made out of smaller parts with electric charge), it won't ever absorb a photon.

    Because of this, we're pretty sure that dark matter doesn't have any electric charge at all. Otherwise we would have seen it by now.
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