Astronomical observations seem to indicate that the intergalactic gas in the universe is a little hotter than it should be. The researchers used computer simulations to propose a solution to this case – an exotic form of dark matter known as dark photons. They can transform into “ordinary” photons, and thus emit heat. Details have been published in the journal Physical review letters.
The dark photons can be found by observing the intergalactic gas from the Lyman Alpha Bubble (LAB), an astronomical object that is a huge hydrogen cloud emitting from the Lyman Alpha spectral line. The largest LABs are more than 400,000 meters in diameter. Light years are among the largest known to astronomers.
The mechanism by which the LABs form is unknown, as is whether they are somehow connected to nearby galaxies. Light from LABs to Earth must travel long distances. From time to time, it passes through a relatively dense mass of neutral hydrogen—a type of hydrogen consisting of one proton and one neutron that permeates clouds of gas throughout the universe. Most light will pass unaffected, but a very specific wavelength of light will be absorbed. It corresponds to the energy difference needed to move an electron from the first to the second energy level within a hydrogen atom.
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When astronomers look at the light from this object, it will look different than usual, except for a break in the wavelength of this specific energy transmission, known as the Lyman alpha line. Light from the LAB will pass through many clouds and clusters of neutral hydrogen. The expansion of the universe is causing the gaps to be redshifted to different wavelengths, with a new gap appearing at a different wavelength depending on the distance from the individual gas clouds. The end result is something like a “jungle”: a series of lines and gaps in the spectrum.
Lyman alpha spectral lines can be used to measure the temperature of any gaseous cloud. If the neutral hydrogens were stationary, a very thin line would appear, but as they move, the gap itself widens as well. The hotter the gas, the greater the kinetic energy of the molecules and the wider the gap (gap).
Dark photons solve the mysteries of the universe
Astrophysicists have pointed out that using this method “something” is not correct, and that the clouds of gases that disperse between galaxies are very hot. Computer simulations of the evolution of these gas clouds predict that they are a little cooler than what we observe, so perhaps there is “something” causing them to heat up. But if it is, we don’t include it in our simulations.
The explanation for this discrepancy may be the presence of dark photons. It’s kind of a hypothetical form of dark matter – invisible matter that makes up about 80% of the planet’s surface. Mass is in the universe, but it does not interact with light. It is not known exactly what dark photons are, but there are several possibilities.
If known photons are carriers of electromagnetism, then dark photons may be carriers of an unknown force that affects all components of the universe. Dark photons would have a small mass, so they could be responsible for dark matter. In the models described, the scientists found that dark photons are capable of another “magic” trick: turning them into ordinary photons.
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The conversion of a dark photon into a photon is theoretically possible, although rare, associated with the emission of thermal radiation. Computer simulations confirming that this may indeed be the case have already been performed. This would explain why there are such differences in the Lyman alpha results, and thus the predictable and measurable temperatures of the universe.
