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Black hole at the center of Milky Way actually dark matter?

Scientific discovery and discussion
GrahamPlatt
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Re: Black hole at the center of Milky Way actually dark matter?

#421002

Postby GrahamPlatt » June 20th, 2021, 7:38 pm

I was jesting. And yes, you’re right. Touché.

ursaminortaur
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Re: Black hole at the center of Milky Way actually dark matter?

#421021

Postby ursaminortaur » June 20th, 2021, 9:34 pm

XFool wrote:
ursaminortaur wrote:I seem to remember seeing a TV program a few years ago about the problems with how quickly super massive black holes formed in the early universe which included direct collapse of dark matter into black holes as one suggested solution. The other solution suggested was dark stars - stars made from a mixture of normal hydrogen and dark matter which were much larger than normal since they were powered by dark matter annihilation.

What would cause the "dark matter annihilation"? Or do we have to envisage anti-dark matter as well?


As explained in the link about dark stars the idea is that the dark matter particles are their own antiparticles

https://astronomy.com/magazine/2018/09/dark-stars-come-into-the-light

A leading theory on dark matter predicts the substance is in the form of weakly interacting massive particles — WIMPS for short. This class of particles is a natural consequence of the idea of supersymmetry, which is a part of the accepted standard model of particle physics, explaining how particles interact with each other and the fundamental forces of the universe.

Supersymmetry theory proposes that each type of particle has an identical, oppositely charged partner called an antiparticle. (Since WIMPS have no charge, they act as their own antiparticles.) When these partners — the particle and antiparticle — meet, they collide with a bang, utterly destroying one another in a shower of light, energy, and, in some cases, newly conceived lighter particles.

XFool
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Re: Black hole at the center of Milky Way actually dark matter?

#421023

Postby XFool » June 20th, 2021, 9:50 pm

ursaminortaur wrote:
XFool wrote:
ursaminortaur wrote:I seem to remember seeing a TV program a few years ago about the problems with how quickly super massive black holes formed in the early universe which included direct collapse of dark matter into black holes as one suggested solution. The other solution suggested was dark stars - stars made from a mixture of normal hydrogen and dark matter which were much larger than normal since they were powered by dark matter annihilation.

What would cause the "dark matter annihilation"? Or do we have to envisage anti-dark matter as well?

As explained in the link about dark stars the idea is that the dark matter particles are their own antiparticles

https://astronomy.com/magazine/2018/09/dark-stars-come-into-the-light

Supersymmetry theory proposes that each type of particle has an identical, oppositely charged partner called an antiparticle. (Since WIMPS have no charge, they act as their own antiparticles.) When these partners — the particle and antiparticle — meet, they collide with a bang, utterly destroying one another in a shower of light, energy, and, in some cases, newly conceived lighter particles.

Sadly, as with most ideas in contemporary physics, that only seems to raise more questions than it answers. Such as: Why is dark matter - particles of which are their own antiparticles - only self annihilating in these dark stars, rather than wherever it was in space? In which case why would it ever be dark?

ursaminortaur
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Re: Black hole at the center of Milky Way actually dark matter?

#421027

Postby ursaminortaur » June 20th, 2021, 10:34 pm

XFool wrote:
ursaminortaur wrote:
XFool wrote:What would cause the "dark matter annihilation"? Or do we have to envisage anti-dark matter as well?

As explained in the link about dark stars the idea is that the dark matter particles are their own antiparticles

https://astronomy.com/magazine/2018/09/dark-stars-come-into-the-light

Supersymmetry theory proposes that each type of particle has an identical, oppositely charged partner called an antiparticle. (Since WIMPS have no charge, they act as their own antiparticles.) When these partners — the particle and antiparticle — meet, they collide with a bang, utterly destroying one another in a shower of light, energy, and, in some cases, newly conceived lighter particles.

Sadly, as with most ideas in contemporary physics, that only seems to raise more questions than it answers. Such as: Why is dark matter - particles of which are their own antiparticles - only self annihilating in these dark stars, rather than wherever it was in space? In which case why would it ever be dark?


This isn't something I know a lot about. However my guess would be that the idea is that these are weakly interacting particles even for interactions with themselves (or even non-interacting apart from via gravity unless they collide head-on). Hence it is only when there are a very large number strongly confined in a small space by gravity that they will they collide in any numbers and hence annihilate. Space is big and the chances of two particles each smaller than an atomic nucleus colliding in empty space are very very low. Two dark matter particles will attract each other gravitationally but gravity is the weakest of all the forces so won't usually have much effect on fast moving particles in open space. Even the dark stars are only supposed to have existed in the early universe when the universe was much smaller and hence when the density of dark matter was much higher.

There have been attempts to see whether dark matter annihilation might be occurring in the centre of the galaxy where dark matter densities might be higher but so far no evidence has been found for that.

https://link.springer.com/article/10.1140/epjc/s10052-015-3713-1

The Milky Way is expected to be embedded in a halo of dark matter particles, with the highest density in the central region, and decreasing density with the halo-centric radius. Dark matter might be indirectly detectable at Earth through a flux of stable particles generated in dark matter annihilations and peaked in the direction of the Galactic Center.
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We used 319.7 live-days of data from IceCube operating in its 79-string configuration during 2010 and 2011. No neutrino excess was found and the final result is compatible with the background. We present upper limits on the self-annihilation cross-section, ⟨σAv⟩, for WIMP masses ranging from 30 GeV up to 10 TeV, assuming cuspy (NFW) and flat-cored (Burkert) dark matter halo profiles, reaching down to ≃4⋅10−24 cm3 s−1, and ≃2.6⋅10−23 cm3 s−1 for the νν¯¯¯ channel, respectively.

1nvest
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Re: Black hole at the center of Milky Way actually dark matter?

#422072

Postby 1nvest » June 24th, 2021, 10:46 pm

:)

Life's a vibe man.

Light is a self perpetuating wave, cycles through being positive electrical, to negative magnetic, to negative electrical, positive magnetic. EM wave. Only at certain parts in that cycle does it appear as matter/antimatter/dark/light. Self annihilating - at some points along the cycle it sums to zero - pops into and out of existence.

At the centre of the MW is a ... locker door. All hail TLF!

:)


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