By: Katelyn Wei

Ghostly cosmic debris is providing us with a unique perspective on our galaxy.

These tiny subatomic particles, also known as neutrinos, have no electric charge and minimal mass. Sometimes people refer to them as “ghost particles.” That is because they effortlessly move through gas, dust, and even stars without leaving any mark. High-energy neutrinos, which convey information about faraway locations, whizz across the cosmos. But the origin of the particles has often remained a mystery.

Currently, scientists have discovered the first evidence of high-energy neutrinos emanating from within our Milky Way. They used particle mapping to produce a new representation of our galaxy. The first was created using a material other than light.

Only a few high-energy neutrinos have previously had their possible origins determined. They’re all extragalactic, coming from somewhere else. From black, two seemed to emerge.

It is now evident that scientists are finding neutrinos coming from both inside and outside of our galaxy, according to Kate Scholberg. She is a physicist who works at Duke University in Durham, North Carolina; she was not involved in the latest mapping effort. There is a lot more to discover, she claims. Learning how to perceive the universe through neutrino eyes can be a lot of fun.

Visible light is used by several telescopes. Others can detect cosmic rays’ charged particles, gamma rays, or X-rays. As it moves across space, each of those forms of light has the potential to be refracted or absorbed. But neutrinos can travel over very large distances.

Kurahashi Neilson, a graduate from Stanford in 2010, accepted the challenge with her group. They examined data from IceCube cascade events dating back ten years. They enlisted the aid of a neural network, an artificial intelligence system. “You can train the neural nets to identify which events are worth keeping,” says Kurahashi Neilson.

She invented this strategy in 2017. Kurahashi Neilson has steadily enhanced it over time. It has now been used by her and her colleagues to pinpoint the neutrinos responsible for creating the new map.

Scholberg calls the analysis impressive, and the technique may have the potential to be developed even more. “Clearly a lot more work needs to be done,” she said. “But it’s very exciting to see the basic expectation of Milky Way neutrinos verified.