For decades, scientists have been puzzled by a strange signal at the North Pole that was picked up by an all-sky survey, and it is now believed that this mysterious signal called anomalous microwave emission (AME) may be caused by tiny grains of cosmic dust.
While this AME signal may have been found at the North Pole, it is a signal that is galaxy-wide, according to Live Science. The first detection of this signal came about in the 1990s when scientists were studying microwave radiation scattered throughout the Milky Way and noticed something quite different from the normal charged particles and synchrotron radiation. Astronomers then questioned whether this was an unexplored part of these typical emissions or whether it was something entirely new.
In a study published on October 27, researchers documented that this signal found at the North Pole was indeed something new, as astrophysicist Clive Dickinson wrote.
“The new data from the C-Band All Sky Survey basically rules [synchrotron radiation and free-free emission] out quite strongly.”
The plan behind the C-Band All Sky Survey is to use two telescopes, with one in California and the other in South Africa, to eventually create a map of the skies, with the frequency being used for this set to 5 gigahertz. With scientists focusing around the region of the North Pole, studying this area using low frequencies was particularly helpful with ruling out two kinds of emissions as sources for this unknown signal.
— Live Science (@LiveScience) November 29, 2018
Princeton University Astrophysicist Bruce Draine, who was not personally involved with the new study, but who has spent a great deal of time researching AME, believes that it is highly probable that dust grains or nanoparticles may be behind this signal that was detected at the North Pole and throughout the galaxy.
“I suspect the emission is coming from spinning nanoparticles, but at this point I’d say we’re not 100 percent certain that that’s the emission process. It might be some other unknown process involving unexpected emission from these dust grains.”
However, if AME is brought about through nanoparticles, scientists are still completely in the dark about what these nanoparticles could be comprised of. And while Polyaromatic hydrocarbons might be plausible, no evidence has been found yet which shows that this is actually the case.
Some researchers have suggested that this signal could be triggered by cosmic dust that is composed of either carbon or silicates, and while a recent study has demonstrated that AME signals found around young stars were made out of extremely small nanodiamonds, so far it is not clear whether nanodiamonds like these may also be causing the AME signal detected above the North Pole.
The new study which examines what may be causing the AME signal above the North Pole is available on arXiv.