Anna Hartz
Neutrinos are some of the universe’s most mysterious particles.
They pass through almost everything, including our bodies, without leaving a trace. Scientists have long struggled to understand them because they interact so rarely with other matter.
Comes from the stars
Researchers know that all stars release huge numbers of these particles. Now, scientists at the Niels Bohr Institute have mapped the flow of neutrinos coming from stars in the Milky Way, according to Videnskab.
Postdoctoral researcher Pablo Martínez-Miravé said most neutrinos from stars other than the Sun come from the inner parts of the Milky Way. They are emitted by stars similar in size to the Sun or larger. He added that he was surprised so many neutrinos come from big stars. Small stars are far more numerous, but they contribute less to the overall neutrino flow. He worked on the study with professor Irene Tamborra.
Neutrinos are extremely light and electrically neutral. They move almost at the speed of light and can pass through the Earth without being stopped. They are created in nuclear reactions in stars, in supernova explosions, and in other energetic cosmic events. Every second, billions of neutrinos pass through each of us without being noticed.
10 million particles a second
The team studied neutrinos from stars beyond the Sun. They calculated that nearly 1,300 neutrinos from other stars hit each square centimeter of Earth every second. Over 10 million of these particles pass through our bodies every second.
The new mapping uses theoretical models of stars combined with data from the Gaia. Gaia has mapped the Milky Way by observing billions of stars over ten years. This allows researchers to estimate the number and energy of neutrinos from stars throughout the galaxy.
Current detectors like IceCube cannot pick up neutrinos from distant stars. Signals from these neutrinos are drowned out by the Sun, supernovae, and Earth’s radioactive decay.
Future detectors such as the Japanese Hyper-Kamiokande or an upgraded Chinese JUNO might be able to detect them. Scientists will need clever ways to sort data so neutrinos from other stars can be separated from the background. This mapping gives a guide for what to look for in upcoming experiments.
