Nanodiamonds could be source of mysterious microwaves across Milky Way

A man used a light on his head to monitor the Milky Way is seen in the night sky around camp in the natural reserve area of Wadi Al-Hitan, or the Valley of the Whales, at the desert of Al Fayoum Governorate, southwest of Cairo, Egypt, August 12, 2015. Wadi Al-Hitan holds an impressive collection of fossils and bones, some of which date back over 40 million years. The entire site resembles an open-air museum with marked trails and itineraries that visitors can follow to admire the fossils and rock formations that extend over a vast area. Picture taken August 12, 2015. REUTERS/Amr Abdallah Dalsh - GF10000173589

A peculiar faint microwave light emanating from certain regions in the Milky Way has been puzzling scientists and astronomers for decades. Researchers now claim that the microwaves have been traced to nanodiamonds found around stars.

Around two decades ago, when scientists measured the microwave radiation in space, they were surprised to find an unexplained emission called Anomalous Microwave Emission (AME).

As per an Independent report, Dr Jane Greaves and her team at Cardiff University managed to understand the source of this radiation. Dr Greaves says, “In a Sherlock Holmes-like method of eliminating all other causes, we can confidently say the best candidate capable of producing this microwave glow is the presence of nanodiamonds around these newly formed stars.”

Up until now, scientists were aware that nanodiamonds as components of meteorites that fall on Earth. However, when Dr Greaves and her team zoomed in on three ‘young stars’ emitting Anomalous Microwave Emission (AME), using powerful telescopes, they could take measurements from the stars’ protoplanetary disks. When these measurements were matched with known infrared signals of nanodiamonds, with layers of hydrogen-bearing molecules on their surface, they were found to be the same. This led to the conclusion that nanodiamonds are responsible for the AME.

Additionally, the arrangement of atoms in nanodiamonds is very unique. Hence, when they spin exceptionally fast, they emit radiation of very small (microwave sized) wavelength.

Before this discovery, it was assumed that some cosmic particles were responsible for the radiation. The best guess was dust from molecules called Polycyclic Aromatic Hydrocarbons.

According to Dr Greaves, since this discovery was made by observing the protoplanetary disks, it helped in understanding chemical features of early solar systems, including our own.