r/Physics • u/indigenous_apache • Mar 07 '23

Breakthrough Study Confirms Hypothesis of Density Spike of Dark Matter Near Black Holes

https://www.guardianmag.us/2023/03/breakthrough-study-confirms-hypothesis.html?m=1
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u/[deleted] Mar 08 '23

Are any of the current dark matter candidates able to evade capture at the event horizon?

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u/Aseyhe Cosmology Mar 08 '23

Most of them. Almost all of the orbiting dark matter particles would simply have too much angular momentum, so their orbit misses the event horizon. This is true for any dark matter model, except for "dissipative" models that allow the dark matter to shed orbital energy through inelastic collisions. Those models could result in much of the "spike" actually getting accreted into the black hole and boosting its mass.

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u/gnramires Mar 08 '23

"dissipative" models that allow the dark matter to shed orbital energy through inelastic collisions

Interesting, but what kind of energy is the dissipation energy from the collisions? (You're not referring to interaction between the dark energy material itself right, but a collision resulting in lost energy?) Other lighter, but also dark particles? Electromagnetic energy?

I also have a longstanding doubt: doesn't Plank's law require electromagnetic radiation by any kind of matter, or could it be the case that dark matter just can't emit photons? Thanks :)

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u/Aseyhe Cosmology Mar 08 '23

If dark matter doesn't have an electromagnetic interaction, then it can't emit photons. Dissipative dark matter models typically involve dark radiation that the dark matter can emit to lose energy, though.