Dark matter interactions other than gravity

[jake jot]

https://phys.org/news/2018-04-dark-interactive.html

"Observations using the Hubble Space Telescope appeared to show that a galaxy in the Abell 3827 cluster - approximately 1.3 billion light years from Earth - had become separated from the dark matter surrounding it.

Such an offset is predicted during collisions if dark matter interacts with forces other than gravity, potentially providing clues about what the substance might be."

If dark matter interacts with forces other than gravity, why is the galaxy expected to be separated from the dark matter surrounding it?

If a baryonic atom indeed has some interaction with dark matter. Are there no tests that can disprove the theory? or our particle detectors not yet sensitive to detect them like the inability to detect gravitons?

 

[phinds]

My understanding is that the "offset" as you call it, is predicted if dark matter does NOT interact other than gravitationally. Google "Bullet Cluster"

 

[jake jot]

My understanding is that the "offset" as you call it, is predicted if dark matter does NOT interact other than gravitationally. Google "Bullet Cluster"

"However, the same group of astronomers now say that new data from more recent observations shows that dark matter in the Abell 3827 cluster has not separated from its galaxy after all. The measurement is consistent with dark matter feeling only the force of gravity. "

If dark matter feel other forces, why would the cluster separate from its galaxy? I don't understand even after reading about bullet cluster.

 

[phinds]

If dark matter feel other forces, why would the cluster separate from its galaxy? I

Asked and answered.

 

[jake jot]

Asked and answered.

You answer was simply "bullet cluster".

Now let's zoom in from macro to micro. Perhaps others who know the answer can chime in.

If dark matter had interaction (theoretically) with baryonic matter, does it mean my bed has dark matter attached to it? Or a single hydrogen atom has an attached atom of dark matter? This aspect is still open and no observations or data in particle physics has falsified it?

 

[PeroK]

You answer was simply "bullet cluster".

Now let's zoom in from macro to micro. Perhaps others who know the answer can chime in.

If dark matter had interaction (theoretically) with baryonic matter, does it mean my bed has dark matter attached to it? Or a single hydrogen atom has an attached atom of dark matter? This aspect is still open and no observations or data in particle physics has falsified it?

The mass of a hydrogen atom is known to a high degree of precision.

 

[Ibix]

I haven't read much more than the introduction to the original 2015 paper, but it actually appears to be talking about self interacting dark matter, not interaction between normal and dark matter.

If I understand correctly, the principle is that when galaxies collide the stars don't slow each other down because they're pretty close to point-like and they just fly past each other. Gas clouds, however, are large and diffuse and experience drag so would lag behind the stars after a collision. Non-interacting dark matter would not experience drag and would keep up with the stars; weakly interacting dark matter would have a bit of drag and would lag a bit behind the stars but not as much as the gas.

The 2015 paper linked above had some evidence for a galaxy's dark matter being off-center, hence implying dark-matter-dark-matter interaction. The update being discussed in the article linked in the OP suggests that the apparent offset was a measurement artifact and hence that dark matter does not interact even with itself.

 

[jake jot]

The mass of a hydrogen atom is known to a high degree of precision.

If there was a dark matter attached to the hydrogen atom, it would weight differently?
But in superstrings theory like E8xE8, there was shadow matter attached to matter. So why did they not use the argument the hydrogen atom was known to a high degree of precision hence shadow matter couldn't exist?

 

[phinds]

You answer was simply "bullet cluster".

No, my answer was in the sentence before "bullet cluster". The BC was just offered as an example of my answer.

 

[PeroK]

If there was a dark matter attached to the hydrogen atom, it would weight differently?

Of course it would, we'd notice if hydrogen was attached to other stuff that had mass. Here's the thing:

1) Chemistry and "ordinary" matter here on Earth are well understood. You cannot invoke a dark matter halo around the chemical elements without completely undermining chemistry. Terrestrial chemistry is not the puzzle where experiment does not reflect the theory.

2) The motion of galaxies is a puzzle - leading to the hypothesis that there might be dark matter (as well as what we have on Earth). Because, without it, galaxy dynamics do not match the theory.

3) If dark matter were here on Earth (in significant quantities) then everything would weigh more than it should. Copper sulphate, for example, would not weigh what it is supposed to weigh by adding up the copper, sulphur and oxygen. It would have the additional mass of all the dark matter as well.

 

[jake jot]

Of course it would, we'd notice if hydrogen was attached to other stuff that had mass. Here's the thing:

1) Chemistry and "ordinary" matter here on Earth are well understood. You cannot invoke a dark matter halo around the chemical elements without completely undermining chemistry. Terrestrial chemistry is not the puzzle where experiment does not reflect the theory.

2) The motion of galaxies is a puzzle - leading to the hypothesis that there might be dark matter (as well as what we have on Earth). Because, without it, galaxy dynamics do not match the theory.

3) If dark matter were here on Earth (in significant quantities) then everything would weigh more than it should. Copper sulphate, for example, would not weigh what it is supposed to weigh by adding up the copper, sulphur and oxygen. It would have the additional mass of all the dark matter as well.

Why can't mirror matter, if it existed, produced the above effects on chemistry too?

https://en.m.wikipedia.org/wiki/Mirror_matter

"However, parity symmetry can be restored as a fundamental symmetry of nature if the particle content is enlarged so that every particle has a mirror partner. The theory in its modern form was described in 1991,[6] although the basic idea dates back further.[2][7][8] Mirror particles interact amongst themselves in the same way as ordinary particles, except where ordinary particles have left-handed interactions, mirror particles have right-handed interactions. In this way, it turns out that mirror reflection symmetry can exist as an exact symmetry of nature, provided that a "mirror" particle exists for every ordinary particle. Parity can also be spontaneously broken depending on the Higgs potential.[9][10] While in the case of unbroken parity symmetry the masses of particles are the same as their mirror partners, in case of broken parity symmetry the mirror partners are lighter or heavier.

Mirror matter, if it exists, would need to use the weak force to interact with ordinary matter. This is because the forces between mirror particles are mediated by mirror bosons. With the exception of the graviton, none of the known bosons can be identical to their mirror partners. The only way mirror matter can interact with ordinary matter via forces other than gravity is via https://en.m.wikipedia.org/w/index.php?title=Kinetic_mixing&action=edit&redlink=1 of mirror bosons with ordinary bosons or via the exchange of https://en.m.wikipedia.org/w/index.php?title=Holdom_particle&action=edit&redlink=1.[11] These interactions can only be very weak. Mirror particles have therefore been suggested as candidates for the inferred dark matter in the universe.[12][13][14][15][16]"

 

[jake jot]

Of course it would, we'd notice if hydrogen was attached to other stuff that had mass. Here's the thing:

1) Chemistry and "ordinary" matter here on Earth are well understood. You cannot invoke a dark matter halo around the chemical elements without completely undermining chemistry. Terrestrial chemistry is not the puzzle where experiment does not reflect the theory.

As you can see in the above article on mirror matter which they proposed can be dark matter. It means ordinary matter can have a mirror matter (or dark matter) halo around the chemical elements.

So when you stated it couldn't happen. Is your context got to it dependent on say electromagnetic field that bind baryonic chemical elements to the dark matter?

In the quote below

"With the exception of the graviton, none of the known bosons can be identical to their mirror partners. The only way mirror matter can interact with ordinary matter via forces other than gravity is via https://en.m.wikipedia.org/w/index.php?title=Kinetic_mixing&action=edit&redlink=1 of mirror bosons with ordinary bosons or via the exchange of https://en.m.wikipedia.org/w/index.php?title=Holdom_particle&action=edit&redlink=1.[11] "

Why does kinetic mixing or exchange of Holdom particles not cause any undermining of chemistry?

2) The motion of galaxies is a puzzle - leading to the hypothesis that there might be dark matter (as well as what we have on Earth). Because, without it, galaxy dynamics do not match the theory.

3) If dark matter were here on Earth (in significant quantities) then everything would weigh more than it should. Copper sulphate, for example, would not weigh what it is supposed to weigh by adding up the copper, sulphur and oxygen. It would have the additional mass of all the dark matter as well.

 

[PeterDonis]

Thread closed for moderation.