Seek for dark matter from Earth to distant galaxies
It’s been a really busy dark matter searching season to this point. Already, one analysis group says they’ve discovered proof for self-interacting dark matter in an unlimited galaxy cluster. And one other group says dark matter is perhaps causing a glow on Jupiter’s darkish facet.
Now three extra analysis teams say they’re extending the hunt for dark matter to new extremes. The primary group is wanting 250,000 light-years away on the Draco dwarf galaxy. A second group thinks we will detect dark matter simply over our heads in our planet’s environment. And a 3rd says the signature of dark matter is printed on the Earth itself.
Outcomes of a peer-reviewed, 18-year-long stellar survey displaying dark matter density within the Draco galaxy appeared within the Astrophysics Journal in July 2024. The scheme for detecting dark matter in Earth’s ionosphere appeared as a preprint paper in Cornell College’s open-source archive – arXiv.org – in Could 2024. And the paper proposing a seek for dark matter alerts in rocks published in July 2024 within the journal Symmetry.
What the heck is dark matter?
We all know nearly nothing about dark matter. We don’t know what it’s comprised of. Darkish matter can’t be felt or heard … at the very least not but. And, in fact, it’s so darkish we will’t see it.
However – due to the work of astronomers like Vera Rubin – we do know that its gravitational impact holds galaxies collectively. If it weren’t for dark matter, there wouldn’t be sufficient mass in galaxies to maintain stars from flinging into space. Meaning no matter it’s, there’s an entire lot of it. Darkish matter makes up roughly 27% of the mass of every little thing there’s.
Dark energy accounts for nearly every little thing else. It makes up 68% or so of the cosmos. That leaves about 5% of the universe’s mass within the type of common matter like us.
So, dark matter is a type of cosmic glue holding issues collectively. However we solely have tantalizing clues about what it’s.
Making a movement map of a pint-sized galaxy’s stars
So the one deal with we have now on dark matter is its pull on every little thing else. Whereas the stuff doesn’t seem to work together with electromagnetic radiation – like mild, gamma radiation and X-rays – it does warp the material of spacetime. In different phrases, it has gravity.
With that in thoughts, some very intelligent individuals designed laptop simulations to point out the place dark matter ought to accumulate in galaxies. Their fashions mentioned it ought to focus on the heart of galaxies, in areas often called density cusps. Nonetheless, some observations advised dark matter is perhaps evenly dispersed in a galaxy.
So researchers with NASA, ESA and the Area Telescope Science Institute (STScI) spent a decade looking by way of 18 years’ price of archival knowledge from the Hubble Area Telescope. With it, they constructed extremely detailed fashions of stellar motions within the Draco dwarf galaxy. STScI’s Eduardo Vitral, the lead writer of the research, described what the group present in a NASA press release:
Our fashions are inclined to agree extra with a cusp-like construction, which aligns with cosmological fashions. Whereas we can not definitively say all galaxies include a cusp-like dark matter distribution, it’s thrilling to have such nicely measured knowledge that surpasses something we’ve had earlier than.
Scientists are already making use of the identical technique to the Sculptor and Ursa Minor dwarf galaxies. The perception into dark matter this technique gives will grow to be extra detailed as new devices just like the Nancy Grace Roman Space Telescope come on-line.
Tuning in dark matter radio alerts
In the meantime, one other trio of physicists mentioned the mannequin they created of Earth’s ionosphere exhibits that dark matter can work together with plasma. And if the plasma has the proper frequency – the identical because the dark matter – then it produces low-frequency radio emissions.
If that speculation is correct, then we simply have to hear in, said the paper’s authors:
An electrically small dipole antenna focusing on the generated radio waves may be orders of magnitude extra delicate to darkish photon and axion-like particle dark matter within the related mass vary. The current research opens up a promising method of testing a hitherto unexplored parameter space which might be additional improved with a devoted instrument.
The catch is dark matter should exist as axions for this to work. These are theoretical elementary particles that scientists first proposed within the Nineteen Seventies. They, too, have never been definitively detected.
Axion quark nuggets
Another paper showing on arXiv.org in Could 2024 wonders if theoretical dark matter particles are behind unusual, yet-to-be-explained occasions on Earth. Writer Ariel Zhitnitsky, a physicist on the College of British Columbia, mentioned the enigmas might be defined by axion quark nuggets putting our planet:
It has been lately argued that there are a variety of mysterious observations that are very exhausting to elucidate by typical physics. The mysterious anomalies embody (however are usually not restricted to) such surprising correlations as temperature variation within the stratosphere, the total electron content material of the Earth’s environment, the earthquake exercise from one hand, and positions of the planets from one other hand.
Zhitnitsky’s remark refers to work by different theorists. Sadly, the temporary out there on-line gives no particulars. Nonetheless, the physicist mentioned these and different puzzles could also be defined by dark matter putting Earth:
It has been hypothesized that the corresponding mysterious correlations are a results of the ‘streaming invisible matter’ which out of the blue turns into very strongly interacting materials when coming into the Earth’s environment. We suggest that a few of these (and lots of different) mysteries is perhaps results of uncommon (however energetic) occasions when the so-called axion quark nuggets (AQN) hit the Earth.
Proof proper underneath our toes?
Theoretical particles are available matched pairs of opposites. On this case, it’s the aptly named “axion antiquark nugget” (AQ¯N). If these nuggets exist, they’ll have little or no mass in comparison with their dimension. Meaning we’d want an enormous detector, one thing about, say, the scale of Earth.
A paper published simply this month (July 2024) proposes a strategy to search for proof of dark matter interactions within the rocks under our toes:
This paper presents a brand new concept for the direct detection of the AQ¯Ns utilizing minerals as pure rock deposits performing as paleo-detectors, the place the latent alerts of luminescence produced by interactions of AQ¯Ns are registered and may be recognized as an elevated and symmetrical deposited dose.
In different phrases, the sunshine produced by AQN/AQ¯N interactions ongoing for the reason that universe started ought to go away a hint on Earth’s geology. The sign ought to be detectable, based on the speculation, in numerous minerals from pure deposits. Now, like dark matter, they simply have to search out it.
Backside line: Current analysis suggests proof for dark matter is – or is perhaps discovered – in excessive areas. Researchers are wanting in distant galaxies and right here on Earth.
Source: Resonant Conversion of Wave Dark Matter in the Ionosphere
Read more: Do dark matter collisions on Jupiter glow in the infrared?
Read more: Did colliding dark matter shape the El Gordo galaxy cluster?
