Is Dark Matter Absorbing Photons and Emitting Undetectable Radiation?

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Discussion Overview

The discussion revolves around the nature of dark matter, specifically whether it absorbs photons and emits undetectable radiation. Participants explore theoretical implications, potential interactions with electromagnetic radiation, and the characteristics that differentiate dark matter from baryonic matter.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that if dark matter is real matter, it must absorb photons and could be heating up, raising questions about its stability and potential emission of radiation.
  • Another participant counters that dark matter is not "real matter" in the traditional sense and argues that significant absorption of photons would create observable dark spots against the background of stars, which we do not see.
  • It is noted that dark matter is considered non-baryonic and interacts primarily through gravitational forces, with uncertain interactions with electromagnetic forces.
  • A claim is made that photon absorption would only occur if dark matter were composed of charged particles, which it is believed not to be, suggesting it does not absorb photons.

Areas of Agreement / Disagreement

Participants express differing views on the nature of dark matter and its interactions with photons. There is no consensus on whether dark matter absorbs photons or emits radiation, and the discussion remains unresolved.

Contextual Notes

Participants acknowledge significant uncertainties regarding the properties and interactions of dark matter, including its potential electromagnetic interactions and the implications of its weakly interactive nature.

rp1220
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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.
 
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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.
 
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 a lot we don't know about dark matter.
 
rp1220 said:
If dark matter is real matter out there in space, it must be absorbing photons from adjacent stars and other bodies.
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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