could DM predate the Big Bang?

[notFritzArgelander]

https://phys.org/news/2019-08-dark-older-big.html

[GCoyote]

Interesting idea.

[smeyer8015]

Does that lead to.... Did DM cause the Big Bang????

[notFritzArgelander]

Does that lead to.... Did DM cause the Big Bang????

I think I'm going to need to look deeper later today to see what the details of this work might say. Can't tell from just the article.

[notFritzArgelander]

OK well that was a bracing read. I have a slight headache.

The paper is at Phys. Rev. Lett. which has shorter papers that are more difficult (because of minimal explanation) to read. But here it is

https://journals.aps.org/prl/abstract/1 ... 123.061302

Dark matter (DM) may have its origin in a pre-big-bang epoch, the cosmic inflation. Here, we consider for the first time a broad class of scenarios where a massive free scalar field unavoidably reaches an equilibrium between its classical and quantum dynamics in a characteristic timescale during inflation and sources the DM density. The study gives the abundance and perturbation spectrum of any DM component sourced by the scalar field. We show that this class of scenarios generically predicts enhanced structure formation, allowing one to test models where DM interacts with matter only gravitationally.

I found the preprint on arXiv but the text has some editorial problems that were cleaned up in the final version which is why I link to the final version of the abstract.

One peculiarity in the authors language is that he sees the universe's history as starting with the exponential growth of inflation with the Big Bang epoch happening later when the usual Friedmann–Lemaître–Robertson–Walker metric cosmology applies. That's a little odd since the Big Bang is usually treated as going back through the inflation to near the singularity where we don't know what happens. Still it's a clearly made distinction that suits his purpose since the strictly inflationary epoch is what he treats in the paper.

His model for the DM is elementary: a simple massive scalar field that ONLY interacts via gravity. That is to say that if anyone ever identifies a DM particle in any laboratory anywhere, his theory is falsified. This DM particle has no interactions except gravitation and so CANNOT be detected in the lab. He assumes that this field/particle is neither the inflaton responsible for cosmic inflation nor the Higgs responsible for Standard Model particle masses.

The particles that arise from this scalar field are spin zero scalars. Since it is neither the inflaton nor the Higgs it is not a cause of the inflationary Big Bang. The predictions of this work include the following salient points. 1) The current abundance of DM in the universe can be completely accounted for by this theory. 2) The introduction of new fields in the inflationary period can have the unwholesome effect of forcing fluctuations in the cosmic microwave background that are larger than observed. This massive scalar field doesn't do that so it is consistent with CMB observations.

I want to thank you folks for asking questions that led me to take a closer look at this work. To the extent of the small headache it caused I need to look at it more until the headache goes away. I'm saving it to my reading list.

[GCoyote]

We encourage you, you translate for us. It's a symbiotic relationship.

[notFritzArgelander]

We encourage you, you translate for us. It's a symbiotic relationship.

Would it be helpful if I translate what I wrote?

The result is that a zero spin massive particle that is neither the particle for inflation (inflaton) nor a Higgs boson. He assumes it interacts only gravitational so it is outside the standard model. This particle can account for all the mass if DM without disturbing the fluctuations seen in the cosmic microwave background.

One point that I had in mind earlier but forgot to write down is that a set of such particles of different masses would account for the observation that some galaxy rotation curves look like there are two components to DM: a superfluid bit and a non superfluid bit. the fact that this is a scalar particle means that superfluidity is on for massive scalars but perhaps not for less massive scalars.

That second paragraph is my response and is not in the paper.

[Michael131313]

Thanks very much n_FA. We appreciate all you do for us.

[helicon]

The study revealed a new connection between particle physics and astronomy. If dark matter consists of new particles that were born before the Big Bang, they affect the way galaxies are distributed in the sky in a unique way. This connection may be used to reveal their identity and make conclusions about the times before the Big Bang too," says Tommi Tenkanen, a postdoctoral fellow in Physics and Astronomy at the Johns Hopkins University and the study's author.

Looking forward to the launch of Euclid in 2022 which will shed more light on this mystery!

[notFritzArgelander]

Thanks very much n_FA. We appreciate all you do for us.

You're welcome. I would do the reading anyway. It takes only a little effort to make a post usually and as long as it's found useful I'll continue on.

My last self translation should have been proofread better, though. It looks garbled. Sometimes there is a mismatch between what is on the page and what I think I am reading. So here is a fix.

What I wrote was:

The result is that a zero spin massive particle that is neither the particle for inflation (inflaton) nor a Higgs boson. He assumes it interacts only gravitational so it is outside the standard model. This particle can account for all the mass if DM without disturbing the fluctuations seen in the cosmic microwave background.

One point that I had in mind earlier but forgot to write down is that a set of such particles of different masses would account for the observation that some galaxy rotation curves look like there are two components to DM: a superfluid bit and a non superfluid bit. the fact that this is a scalar particle means that superfluidity is on for massive scalars but perhaps not for less massive scalars.

What was intended was:

The result is that a zero spin massive particle that is neither the particle for inflation (inflaton) nor a Higgs boson is a plausible DM candidate. He assumes it interacts only gravitationally so it is outside the Standard Model. This particle can account for all the mass of DM without disturbing the fluctuations seen in the cosmic microwave background.

One point that I had in mind earlier but forgot to write down is that a set of such particles of different masses would account for the observation that some galaxy rotation curves look like there are two components to DM: a superfluid bit and a non superfluid bit. the fact that this is a scalar particle means that superfluidity is on for massive scalars but perhaps not for less massive scalars.


I can also add that zero spin particles can make superfluids since they are bosons and thus can make a Bose-Einstein condensate. Such condensates are the mechanism for superfluids and superconductors. (Superconductivity happens when electrons get paired up to make an effective boson via their acoustic coupling.) What is uncertain to me is what temperature to assign to the DM scalar particle. When do they decouple or freeze out from the temperature of the expanding universe? The temperature of decoupling has to be higher than that of the formation of the Standard Model particles.

[notFritzArgelander]

Science Alert has this nicely written article on the topic:

https://www.sciencealert.com/new-study- ... QKKjkbq8Go

It makes clear that there is some flexibility on the part of some cosmologists as to which came first, inflation or Big Bang.