In case darkish matter did not appear mysterious sufficient, a brand new examine proposes that it might have arisen earlier than the Big Bang.
Conventional pondering goes that the Big Bang was the start of the whole lot – matter, darkish matter, area, power, all of it. After the occasion itself, the Universe went by way of a interval of cosmic inflation, which noticed its measurement swell by an element of 10 septillion inside an unfathomable fraction of a second.
But some theories counsel that this inflation interval truly occurred earlier than what we name the Big Bang. And now, physicists on the University of Texas (UT) at Austin have proposed that darkish matter was shaped throughout this temporary window.
The staff calls the brand new mannequin heat inflation through freeze-in, or WIFI. Basically, darkish matter particles can be created from tiny interactions between radiation and particles in a heat ‘thermal tub’ in the course of the inflation interval.
“The factor that is distinctive to our mannequin is that darkish matter is efficiently produced throughout inflation,” says Katherine Freese, a theoretical astrophysicist at UT Austin.
“In most fashions, something that’s created throughout inflation is then ‘inflated away’ by the exponential enlargement of the Universe, to the purpose the place there may be primarily nothing left.”
It’s thought that previous to the Big Bang, the whole lot of the Universe existed in a singularity, some extent of infinite density the place spacetime is infinitely curved. But the identified legal guidelines of physics fully break down there, so some physicists suggest {that a} totally different epoch preceded the Big Bang, as a substitute of a singularity.
This may very well be the collapse of an earlier universe, as within the Big Bounce mannequin – or it may very well be cosmic inflation. This section lasted simply nonillionths of a second, and the power transferred to matter and lightweight to grow to be what we seek advice from because the Big Bang.
From there, the stage is about for the Universe to evolve as described by normal relativity.
The authors of the brand new examine aren’t the primary to counsel that cosmic inflation predated the Big Bang. They aren’t even the primary to counsel that darkish matter arose throughout this epoch. What is new is their mechanism for the way the unusual stuff is produced, in portions that align with astronomical observations.
Warm inflation (the ‘WI’ within the new WIFI mannequin) is an present concept that means that radiation is produced whereas the exponential enlargement is going down. This creates a sort of thermal tub, permitting for tiny however vital interactions to happen.
The driver of cosmic inflation continues to be unknown, however the stand-in is a discipline of hypothetical particles known as inflatons, much like the well-known Higgs boson. In the nice and cozy inflation state of affairs, this inflaton discipline would lose a few of its power to radiation within the thermal tub.
From there, the radiation produces darkish matter particles by way of a course of known as UV freeze-in (there’s the ‘FI’ in WIFI). Essentially, the darkish matter by no means reaches equilibrium with the tub, and the temperature of that tub stays beneath a sure threshold.
According to the staff’s calculations, this mechanism produces sufficient darkish matter to account for the quantity that astronomical observations inform us is on the market.
This does not imply the thriller is solved, after all. It’s only one speculation of many, together with that darkish matter arose in its personal ‘Dark Big Bang’ in a while.
For now, the WIFI mannequin cannot be immediately verified, however no less than a part of it may very well be quickly. Upcoming research of the cosmic microwave background, reminiscent of CMB-S4, might put the thought of heat inflation to the take a look at.
“If future observations verify that heat inflation is the proper paradigm, it will considerably strengthen the case for darkish matter being produced as described in our framework,” says UT physicist Gabriele Montefalcone, co-author of the examine.
The analysis was printed within the journal Physical Review Letters.
