Researchers at the University of California, Riverside, have uncovered new evidence that might point to a mysterious force in the universe.
Their study suggests there could be an unknown particle influencing the structure of the cosmos.
This research, published in the Journal of Cosmology and Astroparticle Physics, uses a unique method called the “Lyman-Alpha Forest” to map out the distribution of hydrogen and, indirectly, dark matter.
The Lyman-Alpha Forest is like a dense tangle of lines on a graph, representing how light from distant quasars and galaxies is absorbed by hydrogen gas.
By analyzing these absorption lines, the scientists can trace the distribution of matter, including the elusive dark matter, across the universe.
Simeon Bird, an associate professor of physics and astronomy and the lead author of the study, explained that each peak in the graph signifies a drop in light at a specific wavelength.
This drop acts like a map, showing where the light encountered matter on its journey to us.
Bird likens this to shadow puppetry, where we guess the shape of an object based on its shadow. In this case, the “shadows” are made by hydrogen molecules between us and the distant light sources.
The researchers used spectrograms, which break down light into its components, much like a rainbow created by a prism.
When light from cosmic sources like quasars passes through hydrogen gas, some frequencies are absorbed, creating dark bands in the spectrogram. These bands indicate the presence of hydrogen, the most abundant element in the universe.
Bird and his team used hydrogen to trace dark matter. He explained that while we have never seen dark matter directly, we know it exists in great abundance.
By following the hydrogen, which acts like a dye in water, the researchers can trace where the dark matter is. Where hydrogen is denser, there’s more dark matter.
This study not only tracks dark matter but also addresses some “tensions” or discrepancies between observations and theoretical predictions about the universe. One such tension involves the number of galaxies at small scales and close distances (low redshifts).
There are two main hypotheses to explain this discrepancy: the existence of a new, unseen particle, or something unusual happening with supermassive black holes inside galaxies that affects galaxy growth.
Bird emphasized that the current data is not yet conclusive enough to claim a discovery. However, if future data supports their findings, it could indicate the presence of a new particle or new physics, rather than black holes disrupting their calculations.
Bird’s coauthors on the paper are M. A. Fernandez and Ming-Feng Ho. The research, titled “Cosmological Constraints from the eBOSS Lyman-α Forest using the PRIYA Simulations,” was funded by the National Science Foundation (NSF) and NASA.
The simulations were run on NSF’s Frontera supercomputer and UCR’s High-Performance Computing Center.
This groundbreaking study provides a glimpse into the unknown forces shaping our universe and opens the door to exciting new discoveries in astrophysics.
