Gravitational waves (GWs) are a signature for some of the most energetic phenomena in the universe, which cause ripples in space-time that travel at the speed of light. These events, spurred by massive accelerating objects, act as cosmic messengers that carry with them clues to their origins. They are also probable sources for highly energetic […]
For over 20 years, physicists have performed experiments that hint at the existence of an elusive fourth type of neutrino, the “sterile” neutrino. Neutrinos—tiny, almost massless particles—are also known as “ghost particles” because they rarely interact with the matter they travel through. On the other hand, the appropriately named sterile neutrino does not interact with […]
Although high-energy cosmic rays have long been observed arriving at Earth, their origins have eluded researchers for years. The key may lie in neutrinos, which are tiny, nearly massless particles that can travel along a straight path from their sources. High-energy neutrinos that originate from outside our solar system are called cosmic neutrinos, which can […]
In 2012, shortly after the IceCube Neutrino Observatory was completed, the IceCube Collaboration announced in Nature an important and unexpected result in neutrino astrophysics: gamma-ray bursts (GRBs), which were one of the two leading candidates for sources of high-energy neutrinos and cosmic rays, did not report any neutrino excesses. Since then, IceCube has continued to […]
The search for the sources of ultra-high-energy cosmic rays (UHECRs) is not a simple one. UHECRs, which are a mixture of protons and heavy nuclei, are the highest energy particles ever measured. They should produce “hotspots” of high-energy neutrinos if they interact with other particles near their point of origin. Six years ago, a first […]
Every six minutes, a neutrino flies through the Antarctic ice sheet, and close to an IceCube sensor—also called a DOM—it interacts with a molecule of ice and creates a tiny amount of light that triggers data-taking for an event in the IceCube neutrino detector. If this is a high-energy event, a beautiful track or a […]
X-ray binaries (XRB) consist of a compact object, such as a neutron star or a black hole, and a noncompact, companion star. When they are close enough, material is pulled off the star and drawn onto the compact companion, releasing intense X-rays that make them some of the most luminous sources in the sky. Microquasars, […]
It took a solar eclipse and a balloon flying up to 5,300 meters to point to outer space as the origin of the ionizing radiation in the atmosphere. The discovery of cosmic rays was made by Victor Hess in 1912 and earned him the Nobel prize in 1936. Since then, scientists around the world use […]
Neutrinos have mass. Their mass is small, extremely small in fact, but contrary to what the Standard Model of particle physics predicts, they do have mass. A consequence of this nonstandard property is that neutrinos oscillate, which means that as they speed through matter or space, their flavor—or type—changes at a rate that depends on […]
We are all surrounded by magnets. Whether they’re on your fridge, in your smartphone, or in your credit card, the magnets you interact with all have one thing in common (well, two things): they each have a north and south pole. Could a magnet ever have just one pole? Yes, according to scientists, and it’s […]