I An apparently obscure question re dark matter

[Buzz Bloom]

TL;DR Summary

I have noticed there are quite few threads discussing dark matter from an astronomy point of view, especially in the Cosmology forum. I have found only a few threads mentioning dark matter in the context of big bang nucleosynthesis (BBN). I recall reading somewhere (I forget where) that during the BBN the ratio of dark matter to baryonic matter influenced the current population ratio of some nucleotides.

Question: How accurately does the observation of the current dark matter to baryonic matter ratio fit with its influence on the BBN?

Some good references would be very helpful.

Here are some references that I think might be a little helpful.
(Mar 6, 2004) https://www.physicsforums.com/threads/under-abundance-of-lithium-may-solve-existence-dm.15780/
(Nov 1, 2007) https://www.physicsforums.com/threads/no-dark-matter.194931/#post-1489416
(Sep 27, 2010) https://www.physicsforums.com/threa...d-by-increasing-the-dark-matter-ratio.432651/
(Oct 28, 2014) https://www.physicsforums.com/threads/big-bang-ruled-out-as-origin-of-lithium-6.770264/#post-4895937
(Nov 17, 2015) https://www.physicsforums.com/threads/wimps-over-machos.843257/#post-5291689

 

[anorlunda]

Question: How well do the FLRW models' provide a dark matter to baryonic matter ratio consistent with its influence on the BBN?

Huh? The FLRW models are for expansion of space. They have nothing to do with baryogenesis, nucleosynthesis, or any particle synthesis.

So, please restate your question more clearly. Also look up the definitions of baryogenesis and nucleosynthesis.

 

[Buzz Bloom]

Huh? The FLRW models are for expansion of space.

Hi @anorlunda:

I apologize for my careless error. I edited it, replacing "FLRC" with "ΛCDM". I hope you will find it OK now.

Regards,
Buzz

 

[timmdeeg]

Question: How well do the ΛCDM models' provide a dark matter to baryonic matter ratio consistent with its influence on the BBN?

The matter density is dominated by dark matter. ΛCDM models can't say anything about a dark to baryonic matter ratio. This ratio is taken from observation. The $\rho$ in the Friedmann Equations doesn't distinguish between dark and baryonic matter anyway.

 

[Buzz Bloom]

ΛCDM models can't say anything about a dark to baryonic matter ratio. This ratio is taken from observation.

Hi @timmteeg:

I apologize again for my carelessness. I have again edited my question to take into account your post.
I hope you will find it OK now.

Regards,
Buzz

 

[timmdeeg]

Question: How accurately does the observation of the current dark matter to baryonic matter ratio fit with its influence on the BBN?

We know that ratio by analyzing the CMB power spectrum. But I don't know how it relates to the matter production at the end of inflation.

Perhaps this helps:

https://www.researchgate.net/publication/342057574_Reheating_and_post-inflationary_production_of_dark_matter

 

[Buzz Bloom]

Hi @timmdeeg:

Thank you for the reference. When I downloaded the paper the title seems to be dealing with
"Reheating and post-inflationary production of dark matter".
There does not seem to be any discussion of how the ratio of dark matter to baryon matter effects BBN nucleosynthesis.

Regards,
Buzz

 

[gmax137]

nucleotides

Am I the only one finding this confusing? Does this word have a meaning outside biology?

 

[Vanadium 50]

Does this word have a meaning outside biology?

It's in the universe's very DNA.

 

[Buzz Bloom]

Hi @gmax137 and @Vanadiym 50:

Thank you for finding one more of my careless errors. I made the correction to post #7.

Regards,
Buzz

 

[alantheastronomer]

How accurately does the observation of the current dark matter to baryonic matter ratio fit with it's influence on Big Bang Nucleosynthesis?

Peebles determined the dark matter to baryonic matter ratio to be 5:1 based on acoustic oscillations in the cosmic microwave background radiation for which he won a Nobel prize. Only after the recombination of electrons with protons to produce neutral hydrogen was this radiation able to be observed.

The era of nucleosynthesis came some time before that, so I'm not sure how the effect of dark matter on early nucleosynthesis would be able to be determined, so I'd be interested in seeing that reference if you're ever able to remember it!

A good place to look for other papers that might discuss the topic would be on arXiv by doing a search cross referencing the topics "Big Bang nucleosynthesis" and "Dark Matter".

 

[horacio torres]

Dark Matter is for us like the sun for the Neandertals

Horacio

 

[ohwilleke]

There are many papers that seek to constrain potential dark matter theories based upon Big Bang Nucleosynthesis. Also, the Lithium problem (a deficit of Lithium-7 from what would be expected from BBN) is itself a problem for the standard LambdaCDM cosmology (but could be due to something as simple as a lack of understanding of how post-BBN star chemistry impacts Lithium-7 levels observed today).

This powerfully constrains, for example, the cross section of interaction that a dark matter candidate can have with ordinary matter.

For example, it rules out the shaded area of parameter space (the shaded area on the left) for a particular class of dark matter candidates in the chart from https://arxiv.org/abs/2107.12377 because it would make it appear that there are more effective neutrino species that astronomy observations support for low mass dark matter candidates with meaningful (i.e. at least as strong as neutrino) interactions with ordinary matter.

This limitation on turns out to be quite useful, because light dark matter candidates are particularly hard for direct dark matter detection experiments to exclude because the noise from neutrinos themselves can overwhelm a dark matter signal in those experimental designs. Where direct detection experiments are available they usually provide the strongest exclusions of the dark matter candidate parameter space, while BBN provides an almost completely non-overlapping exclusion for lighter dark matter candidates with comparable cross-section of interaction cutoffs.

Together these constraints largely rule out dark matter candidates that interact with ordinary matter at a strength equal to or greater than neutrino interactions with ordinary matter via the weak force, across almost the entire range of dark matter candidate masses for a very large and generic class of dark matter candidates.

For example, this is very constraining for supersymmetric particle candidates, since these candidates generally have weak force interaction strengths that are well defined, a priori, in the theory from which they are derived.

Another recent paper derives a similar constraint for essentially the same reasons (the paper with the chart is mostly looking at another issue and incorporating prior BBN constraint on DM research). https://arxiv.org/abs/2106.07122

BBN can also be used to constrain "sterile neutrinos" (a subset of "heavy neutral leptons") that oscillate with ordinary neutrinos but otherwise don't interact with ordinary matter. https://arxiv.org/abs/2006.07387

BBN also constrains DM that decays to visible particles. https://arxiv.org/abs/1910.06272

Macroscopic dark matter candidates, meanwhile, can be constrained by the change in the baryon density between the end of the Big Bang Nucleosynthesis (BBN) and the Cosmic Microwave Background (CMB) decoupling, inferred from astronomy observations. https://arxiv.org/abs/2105.13932 Similarly, it imposes constraints on primordial black hole dark matter theories. https://arxiv.org/abs/2002.12778

BBN has also been used to constrain non-LambdaCDM cosmology theories. https://arxiv.org/abs/2104.11296

In general, however, such constraints are tricky because there are usually multiple different mechanisms that can have the same BBN impact (or lack thereof). For example, a MOND inspired cosmology without dark matter doesn't have the "Lithium problem" found in LambdaCDM BBN fits to astronomy observations, but has a lower statistical significance deuterium problem.

The lithium problem can also be addressed with light dark matter candidates produced partially or in full, non-thermally. https://arxiv.org/abs/1912.05563

As a general rule, the more sterile a dark matter candidate is in terms of interactions with ordinary matter, and the more symmetrically (more precisely, the more isotropically and homogeneously) dark matter is distributed at the time of BBN, the less of an impact it has on BBN. And, because BBN happens so early after the Big Bang (between about 10 seconds and 20 minutes after the Big Bang), there isn't a lot of time for anisotropy or inhomogeneity to emerge in dark matter particle distributions from random quantum variations by then.