Thanks to gravity, no less than we’re conscious darkish matter exists. We additionally know it is eerily plentiful, accounting for about 85 p.c of all matter within the Universe.
Aside from that, although, we’re fairly clueless. We do not know what darkish matter is or the place it got here from, and whether it is made from some form of weakly-interacting type of matter, we nonetheless cannot instantly detect a single particle of it.
According to a theoretical examine by two researchers from Colgate University within the US, our ongoing failure to unmask darkish matter – even with newer, extremely delicate detection strategies – warrants rethinking the character and potential origins of this mysterious stuff.
Rather than rising from the Big Bang together with extraordinary baryonic matter, darkish matter might have arisen barely later in its personal ‘Dark Big Bang,’ the examine’s authors write. It could now inhabit a darkish sector largely indifferent from our seen sector, interacting completely via gravity.
Gravity has taught us what little we do find out about darkish matter thus far. We name the ghostly substance darkish matter as a result of it does not work together with gentle or different electromagnetic radiation, rendering it invisible to us.
Yet given its gravitational sway on galaxies and galaxy clusters – plus different clues, like its impact on the cosmic background radiation – we have now sturdy proof darkish matter exists. We’re simply nonetheless at nighttime about almost all the things else, together with what it’s and the place it got here from.
The hunt for darkish matter has targeted largely on weakly interacting huge particles, or WIMPs. These hypothetical elementary particles would work together through two of the 4 elementary forces: gravity and the weak nuclear drive (however not electromagnetism or the sturdy nuclear drive).
Decades of looking have yielded no affirmation of WIMPs’ existence, dimming their attract a bit and displacing extra scientific curiosity towards different potential explanations of darkish matter.
“As WIMPs proceed to evade detection, it’s turning into more and more vital to contemplate darkish sectors which can be strongly decoupled from the seen sector,” write the authors of the brand new examine, physicist Cosmin Ilie and undergraduate researcher Richard Casey.
In 2023, two different researchers – Katherine Freese and Martin Winkler from the University of Texas at Austin – proposed an intriguing idea: Maybe darkish matter was fashioned individually to the preliminary cosmic enlargement in a second huge bang, which they dubbed the Dark Big Bang.
That would problem the way in which many scientists at the moment envision this pivotal period, with all matter and radiation within the Universe (together with darkish matter, no matter it’s) originating from the identical sector of physics.
According to Freese and Winkler, nonetheless, a Dark Big Bang is in keeping with the proof for darkish matter – so long as it occurred promptly, inside a couple of month of the primary Big Bang.
In this state of affairs, darkish matter particles come up from the decay of a quantum discipline that {couples} solely to the darkish or hidden sector; a hypothetical assortment of particles and forces past our present data of physics.
The Dark Big Bang would unleash a first-order cosmological section transition at nighttime sector, akin to the reality-shifting adjustments our seen sector skilled after the primary Big Bang, which transformed vacuum vitality right into a sizzling plasma of radiation and particles.
In their new examine, Ilie and Casey delve deeper into this concept, exploring its feasibility and testing a spread of various Dark Big Bang eventualities that match with present experimental knowledge.
Their work helps strengthen the case launched by Freese and Winkler, not solely confirming the potential of a Dark Big Bang, but in addition comprehensively assessing the vary of the way such an occasion may need unfolded.
Among their findings, Ilie and Casey reveal a beforehand unexamined array of potential parameters for the daybreak of darkish matter. They additionally lay out choices for testing this idea additional, together with the potential existence of detectable traces – like gravitational waves – left behind by these eventualities.
“Detecting gravitational waves generated by the Dark Big Bang might present essential proof for this new idea of darkish matter,” Ilie says.
And whereas darkish matter appears unlikely to surrender its secrets and techniques simply, there’s trigger for optimism that we are going to clear up this cosmic thriller, he notes.
“With present experiments just like the International Pulsar Timing Array (IPTA) and the Square Kilometer Array (SKA) on the horizon, we could quickly have the instruments to check this mannequin in unprecedented methods,” Ilie says.
For instance, researchers with the NANOGrav analysis collaboration – which is a part of IPTA – introduced in 2023 they’ve discovered proof for a gravitational-wave background within the Universe.
This might assist take a look at the Dark Big Bang idea, Ilie and Casey say, setting the stage for additional analysis which may lastly shed a bit gentle on darkish matter.
The examine was printed in Physical Review D.
