Neutrinos Archives

November 16, 2024November 16, 2024 by Alan Boyle

America’s Particle Physics Plan Spans the Globe — and the Cosmos

Illustration showing subatomic particles and galaxies in collision — Particle physics experiments address mysteries at subatomic and astronomical levels. (Illustration by Olena Shmahalo for U.S. Particle Physics)

RALEIGH, N.C. — Particle physicist Hitoshi Murayama admits that he used to worry about being known as the “most hated man” in his field of science. But the good news is that now he can joke about it.

Last year, the Berkeley professor chaired the Particle Physics Project Prioritization Panel, or P5, which drew up a list of multimillion-dollar physics experiments that should move ahead over the next 10 years. The list focused on phenomena ranging from subatomic smash-ups to cosmic inflation. At the same time, the panel also had to decide which projects would have to be left behind for budgetary reasons, which could have turned Murayama into the Dr. No of physics.

Although Murayama has some regrets about the projects that were put off, he’s satisfied with how the process turned out. Now he’s just hoping that the federal government will follow through on the P5’s top priorities.

June 24, 2024June 24, 2024 by Matt Williams

Simulating the Last Moments Before Neutron Stars Merge

Volume rendering of density in a simulation of a binary neutron star merger. New research shows that neutrinos created in the hot interface between the merging stars can be briefly trapped and remain out of equilibrium with the cold cores of the merging stars for 2 to 3 milliseconds. Credit: David Radice/Penn State

When stars reach the end of their life cycle, they shed their outer layers in a supernova. What is left behind is a neutron star, a stellar remnant that is incredibly dense despite being relatively small and cold. When this happens in binary systems, the resulting neutron stars will eventually spiral inward and collide. When they finally merge, the process triggers the release of gravitational waves and can lead to the formation of a black hole. But what happens as the neutron stars begin merging, right down to the quantum level, is something scientists are eager to learn more about.

When the stars begin to merge, very high temperatures are generated, creating “hot neutrinos” that remain out of equilibrium with the cold cores of the merging stars. Ordinarily, these tiny, massless particles only interact with normal matter via weak nuclear forces and possibly gravity. However, according to new simulations led by Penn State University (PSU) physicists, these neutrinos can weakly interact with normal matter during this time. These findings could lead to new insights into these powerful events.

May 16, 2024May 16, 2024 by Andy Tomaswick

Scientists Test for Quantum Gravity

The tension between quantum mechanics and relativity has long been a central split in modern-day physics. Developing a theory of quantum gravity remains one of the great outstanding challenges of the discipline. And yet, no one has yet been able to do it. But as we collect more data, it shines more light on the potential solution, even if some of that data happens to show negative results.

December 16, 2023December 16, 2023 by Matt Williams

Scientists are Recommending IceCube Should be Eight Times Bigger

This image shows a visual representation of one of the highest-energy neutrino detections superimposed on a view of the IceCube Lab at the South Pole. Credit: IceCube Collaboration

The IceCube Neutrino Observatory, operated by the University of Wisconsin-Madison (UW-M), located at the Amundsen–Scott South Pole Station in Antarctica, is one of the most ambitious neutrino observatories in the world. Behind this observatory is the IceCube Collaboration, an international group of 300 physicists from 59 institutions in 14 countries. Relying on a cubic kilometer of ice to shield from external interference, this observatory is dedicated to the search for neutrinos. These nearly massless subatomic particles are among the most abundant in the Universe and constantly pass through normal matter.

By studying these particles, scientists hope to gain insight into some of the most violent astrophysical sources – such as supernovae, gamma-ray bursts, merging black holes and neutron stars, etc. The group of scientists tasked with advising the U.S. government on particle physics research is known as the Particle Physics Project Prioritization Panel (P5). In a recent draft report, “Pathways to Innovation and Discovery in Particle Physics,” the P5 team recommended a planned expansion of IceCube. This recommendation is one of several that define the future of astrophysics and particle physics research.

August 24, 2023August 24, 2023 by Scott Alan Johnston

IceCube-Gen2: 8 Cubic Kilometers of Ice, 5 Times the Sensitivity

The IceCube Neutrino Detector is an observatory unlike any other. Using sensors embedded inside a square kilometer chuck of Antarctic ice, it detects tiny particles called neutrinos, which rarely interact with ordinary matter and are incredibly hard to capture. IceCube has had several major successes in the last few years, including this summer’s announcement of a neutrino map of the Milky Way galaxy. But scientists are pushing up against the limits of IceCube’s capabilities, and plans are in the works for IceCube-Gen2: a detector 5 times as sensitive and 8 times as large, with a radio antenna array across four hundred square kilometers. IceCube Gen2 will increase the number of neutrino detections by an order of magnitude, and will be able to better pinpoint the sources from which the neutrinos are emitted.

August 10, 2023August 10, 2023 by Brian Koberlein

Astronomers Search for Dark Matter Annihilation at the Center of the Earth

How IceCube can detect neutrinos from Earth's core. Credit: IceCube Collaboration

Dark matter is one of the thorniest mysteries of modern cosmology. On the one hand, astronomers have gathered a wealth of supporting evidence through galaxy clustering statistics, gravitational lensing, and cosmic microwave background fluctuations, on the other hand, there are no particles in the standard model of particle physics that could account for dark matter, and we haven’t been able to detect its effect locally. It’s a solid theory where we just can’t seem to fully pin it down. That usually means we’re just a breakthrough away from confirming or overthrowing dark matter. The good news is that there are several projects searching for dark matter, and one of them, the IceCube Neutrino Observatory, has just released a new result.

November 4, 2022November 4, 2022 by Evan Gough

IceCube Senses Neutrinos Streaming From an Active Galaxy 47 Million Light-Years Away

This is a Hubble Space Telescope image of the Messier 77 spiral galaxy. Scientists working with the IceCube Neutrino Observatory detected neutrinos emanating from the galaxy's core. Image Credit: By NASA, ESA & A. van der Hoeven - http://www.spacetelescope.org/news/heic1305/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=25328266

Researchers using the IceCube Neutrino Observatory have detected neutrinos emanating from the energetic core of an active galaxy millions of light-years away. Neutrinos are difficult to detect, and finding them originating from the galaxy is a significant development. What does the discovery mean?

September 29, 2021September 29, 2021 by Evan Gough

Even the Quiet Supermassive Black Holes are Blasting out Neutrinos and Gamma Rays

Is there anywhere in the Universe where we can escape from radiation? Certainly not here on Earth. And not in space itself, which is filled with diffuse radiation in the form of gamma rays and neutrinos. Scientists have struggled to explain where all those gamma rays and neutrinos come from. A trio of researchers is proposing a source for all that radiation in a new paper: resting black holes.

July 29, 2021July 29, 2021 by Andy Tomaswick

Searching for Dark Matter Inside the Earth

Dark matter remains one of the greatest mysteries in science. Despite decades of astronomical evidence for its existence, no one has yet been able to find any sign of it closer to home. There have been dozens of efforts to do so, and one of the most prominent just hit a milestone – the release and analysis of 8 years of data. The IceCube Neutrino Observatory will soon be releasing results from those 8 years, but for now let’s dive in to what exactly they are looking for.

March 9, 2021March 9, 2021 by Andy Tomaswick

Astronomers Track a Neutrino Back to the Source. Where a Black Hole Tore Apart a Star

Neutrinos are notoriously finicky particles. Hundreds of trillions pass through a person’s body every second, yet they hardly seem to interact with anything (though they actually do a lot). Even more hard to find are the “high energy” neutrinos that are believed to be formed as the outcome of some of the most violent events in the universe. Now, researchers using NASA’s Swift telescope have found a high energy neutrino for the first time from one type of those ultra-violent events – a tidal disruption. But something was a little bit off about it.