A team of physicists used supercomputers to identify discrepancies between observations of the universe and theoretical predictions about its structure.
The team used PRIYA, a series of simulations that use visible light data from the two surveys to refine cosmological parameters, to determine constraints on measurements of the universe and its evolution. The team’s work was published earlier this month Journal of Cosmology and Astroparticle Physics.
The team used PRIYA to study spectrograms, images of hydrogen emission lines in the universe. Spectrograms capture Lyman alpha forests, dense collections of absorption lines in the spectrum from quasars, extremely bright sources in the universe.
In the team’s spectrograms, spikes in the missing frequencies represent “atoms and molecules that the light encountered along the way,” UC Riverside physicist and study co-author Simeon Bird said in a university release. “Each type of atom has a particular way of absorbing light, which leaves a kind of signature in the spectrogram that makes it possible to track their presence, particularly that of hydrogen, the most abundant element in the universe,” Bird added.
Dark matter is the collective name for about 27% of the universe’s composition. It is so named because it has never been directly observed, but its presence is evident through its gravitational effects. Instruments such as the Euclid Space Telescope are collecting data that may shed light on the makeup of the dark universe.
At the same time, ground-based instruments such as the DM Radio project are gradually narrowing the potential mass range of particles that could be responsible for dark matter.Strong candidates for dark matter include weakly interacting massive particles (WIMPs), axions, and hidden (or dark) photons.
Mapping the distribution of dark matter throughout the universe can also reveal how well theoretical models of the universe match observational data, and a recent study used the Lyman Alpha Forest to reveal the location of dark matter in the universe.
“Dark matter is gravity-driven, so it has gravitational potential,” Bird says. “Hydrogen gas falls into it, and we use that as a tracer for dark matter.”
The team uses the model not only to monitor the concentration of dark matter in the universe, but also to investigate discrepancies between observations of the universe and theoretical predictions of its structure.
Byrd offered two leading theories as to why the two don’t match up: that supermassive black holes at the centers of galaxies could be confounding the team’s calculations about the structure of the universe, or that there’s new physics at work that hasn’t yet been discovered.
“If this holds true in the later data sets, it becomes much more likely that it’s not a black hole that’s messing up the calculations, but rather a new particle or a new type of physics,” Bird said.
In other words, we’ll need a lot more data to unlock the universe’s biggest unsolved mysteries. Thankfully, there are plenty of observatories currently available and planned to collect that data.
