Particle production in an expanding universe?

[Suekdccia]

TL;DR Summary

Particle production in an expanding universe?

I was reading this interesting article [1] which talks about particle production in an expanding universe.

Usually this process is proposed to have occurred in the early universe, when the expansion was in the inflationary phase and it was so powerful that matter was created in particle production mechanisms.

However, can particles be produced in an accelerating expanding universe like our current one? Can particles be produced by the universe's expansion with the current conditions of our own one?[1]: https://iopscience.iop.org/article/10.1088/1361-6633/ac1b23

 

[vanhees71]

Here's the arXiv link to this publication:

https://arxiv.org/abs/2112.02444

 

[mathman]

In general particles are produced from pairs of high energy photons. Extremely rare these days.

 

[George Jones]

However, can particles be produced in an accelerating expanding universe like our current one? Can particles be produced by the universe's expansion with the current conditions of our own one?[1]: https://iopscience.iop.org/article/10.1088/1361-6633/ac1b23

In general particles are produced from pairs of high energy photons. Extremely rare these days.

Actually, pair production by photons is not the type of particle creation about which the articles talks. The article is about "particle creation" by dynamic spacetimes, something like a cosmological version of Hawking radiation.

From the arXiv version: page 18 "After inflation has ended, and the universe has entered a radiation or a matter dominated epoch, gravitational particle creation would normally be expected to become very small, as the spacetime curvature has become relatively small, and the expansion time correspondingly large."; page 19 "Another context in which quantum particle creation could become important in the late universe would if the effective equation of state of the matter in the universe were of the form $p=w\rho$, where $w<-1$, sometime called phantom matter. The equation of state causes such rapid expansion that curvature singularity arises, the 'Big Rip'"

So far, observations are consistent with $w=-1$, which gives very very small particle production for the current accelerating phase of the universe.

 

[Suekdccia]

Actually, pair production by photons is not the type of particle creation about which the articles talks. The article is about "particle creation" by dynamic spacetimes, something like a cosmological version of Hawking radiation.

From the arXiv version: page 18 "After inflation has ended, and the universe has entered a radiation or a matter dominated epoch, gravitational particle creation would normally be expected to become very small, as the spacetime curvature has become relatively small, and the expansion time correspondingly large."; page 19 "Another context in which quantum particle creation could become important in the late universe would if the effective equation of state of the matter in the universe were of the form $p=w\rho$, where $w<-1$, sometime called phantom matter. The equation of state causes such rapid expansion that curvature singularity arises, the 'Big Rip'"

So far, observations are consistent with $w=-1$, which gives very very small particle production for the current accelerating phase of the universe.

Even if at small rates, is this "cosmological particle creation" supported by mainstream and verified physics?

 

[George Jones]

Even if at small rates, is this "cosmological particle creation" supported by mainstream and verified physics?

Do you consider Hawking radiation to be mainstream and verified?

 

[vanhees71]

I'd say Hawking radiation is "mainstream" but not observed yet.