A new paper published yesterday in the journal Nature announced that the remaining reservoir of missing baryons in our universe — the vast proportion of unaccounted-for protons, neutrons, and electrons that exist beyond the boundaries of galaxies — has finally been found.
As the Inquisitr previously reported, baryons are tiny particles made up of quarks, elementary building blocks of atoms and can create both protons and neutrons in atoms, and make up all physical objects in existence.
Previous studies have suggested that all the ordinary matter that we know of — stars, planets, galaxies, galaxy clusters — represents only about 10 percent of the universe’s baryon content. Another 60 percent is found in the hot gas that occupies the space between galaxies, notes Science Daily.
About two-thirds of the universe’s “missing matter” was reportedly uncovered in 2014 and 2017. And, according to Gizmodo, the remaining third of the matter created by the Big Bang has now been detected as well.
Last year, two independent teams of scientists declared that they had pinned down half of the “missing matter” in the universe inside filaments of hot intergalactic gas, also known as the warm-hot intergalactic medium, the Inquisitr reported at the time. This year, an international team of researchers from various universities in Europe and the United States has managed to pinpoint the hiding place of the rest of the universe’s missing baryons.
According to the research team, science has known for several decades that “the observed number of baryons in the local universe falls about 30 to 40 percent short of the total number of baryons predicted by Big Bang nucleosynthesis” — the process in which the nuclei of atoms were formed through nuclear reactions inside early stars at the beginning of the universe.
The Source Of The Missing Baryons
In their paper, the scientists showed that they have uncovered the hidden 30 percent of the universe’s baryons in the filaments of hot oxygen gas observed in a quasar found several billion light-years away from Earth. Quasars are among the brightest and most distant objects in the universe.
The team analyzed the light of this particular quasar with the X-ray Multi-Mirror Mission (XMM-Newton) satellite of the European Space Agency (ESA). While studying the quasar’s X-ray spectrum, they stumbled upon two locations where the light was absorbed by two filters made out of warm-hot intergalactic medium.
According to their paper, these filters of hot gas inside the quasar’s light appeared to be swallowing highly-ionized particles of oxygen, unveiling the filaments of hot oxygen gas as the source of the missing baryons.
“The team found the signatures of a type of highly ionized oxygen gas lying between the quasar and our solar system—and at a high enough density to, when extrapolated to the entire universe, account for the last 30 percent of ordinary matter,” revealed a news release by the University of Colorado Boulder (CU Boulder), which was involved in the new discovery.
Study co-author Michael Shull, an astrophysicist at CU Boulder, chimed in on the importance of this discovery.
“This is one of the key pillars of testing the Big Bang theory: figuring out the baryon census of hydrogen and helium and everything else in the periodic table.”
The new study boasts the longest observation ever made with ESA’s space-based telescope — a total of 20 days, accomplished over two sessions.
“We were granted a lot of time,” study lead author Fabrizio Nicastro, an astrophysicist with the Italian National Institute of Astrophysics, told Gizmodo. “And we got this detection.”
As his team explains, the two filters of hot intergalactic gas were monitored for more than two years, revealing “no variability” and “no associated cold absorption.” This proves they didn’t “originate from the quasar’s intrinsic outflow or the host galaxy’s interstellar medium,” which can only mean that “the missing baryons have been found,” the scientists wrote in the paper.
The Missing Baryons Have Been Located, Maybe
While they are convinced that they have made a breakthrough discovery, other researchers deem their conclusions as a bit of a stretch.
For instance, Jessica Rosenberg, an associate professor at George Mason University in Virginia, noted that, although “tantalizing,” these results are “a bit of a leap” since it’s difficult to imagine that all the missing matter in the universe can be accounted for by a single source of light with two absorptions found in a distant quasar.
Astronomer Jason Tumlinson, from the Space Telescope Science Institute in Maryland, agrees that “a larger sample” would be needed to verify these results.
“This is one detection, and so deriving a cosmic mean density of hot gas is a bold thing to do — and not necessarily in a good way.”