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IceCube Observatory Creates First Map of Milky Way Without Using Electromagnetic Waves



Simulations on PSC’s Bridges-2 System Help Identify Signals in Huge Antarctic Ice Sheet Neutrino Detector

Newswise — We’ve learned a lot about the Universe from telescopes that are sensitive to anything from high-energy gamma waves to visible light to low-energy radio waves. But detecting such electromagnetic waves has limitations. Using PSC’s Bridges-2 system to simulate signals in their Antarctic IceCube detector, an international collaboration of scientists has now made the first map of the Milky Way galaxy using particles called neutrinos — the first map of a cosmic structure that didn’t depend on electromagnetic waves.


As our technology has progressed, we have devised new and more ingenious ways to observe and measure the Universe. Telescopes let us see objects in visible light; radio telescope dishes let us see new objects, as well as different behaviors by previously seen objects. Space launches allowed telescopes to have unprecedented clarity, as well as to see through opaque clouds using infrared light. Each of these leaps in technology literally opened new worlds for us. But they all detected electromagnetic waves, which can be distorted, absorbed, and generally scrambled by stuff in between us and what we’re trying to look at.

The first detection of gravitational waves in 2016 completely changed that. It represented a completely new way of looking. A year later, the IceCube Observatory in Antarctica made an equally momentous detection: the first pinpointing of an object out in space using weird particles called neutrinos. We now had three “messengers” to probe the universe with, each telling us different things about the objects that produced them.

“The original point [for IceCube] was this phenomenon called cosmic rays. [Scientists] discovered them over 120 years ago. But we had no idea where they were coming from … They don’t travel in straight lines. They’re being deflected so we can’t really point back to the sources. And then other messengers like gamma rays get absorbed [by] dust … So at the longest distances and highest energies anything from radio out to the gamma rays is being absorbed. It’s basically dark to us.” — Benedikt Riedel, University of Wisconsin

The IceCube Collaboration scored several firsts. First localization of a source of cosmic neutrinos. With colleagues using traditional telescopes, first co-detection of neutrinos and electromagnetic signals from a neutron star, pinpointing a source of cosmic rays. Simulations on PSC’s supercomputers helped them prepare for these discoveries. For their next step, the team wanted to take their revolutionary detector to a new level. They wanted to map the entire Milky Way galaxy. If successful, it would be the first cosmic map that didn’t depend on electromagnetic waves.

To make this happen, they once again turned to PSC, and the center’s Bridges-2 supercomputer.


To understand how PSC’s NSF-funded, ACCESS-program-allocated Bridges-2 supported IceCube’s work, you first must understand a little about neutrinos.

Neutrinos have mass, but just barely. They also have no electrical charge. So unlike the particles that make up normal matter, they’re what physicists call “weakly interacting.” Neither gravity, electrical charge, nor magnetic fields have much of an effect on them. Because of that, they rarely interact with matter. Right now, 100 trillion neutrinos are passing through your body every second. But if you live to be 80 years old, on average only one of them will have interacted with the matter in your body.

The IceCube neutrino detector, then, had its work cut out for it. Because such an incredibly tiny fraction of neutrinos interacts with matter, the scientists who designed IceCube had to put an immense amount of matter in the detector. They hit on the idea of taking roughly a cubic kilometer of Antarctic ice and drilling it to insert hundreds of detectors, sensitive to the blue Cerenkov radiation light expected from these rare collisions.

First, though, they had to work through a bunch of challenges. In theory, a neutrino could create a line of light as it crashed through the ice, allowing the detectors’ positions and times of detection to trace that line back to the neutrino’s cosmic source. But sometimes, the detection is more of a sphere. The scientists would also have to screen out detections due to backgrounds coming from cosmic ray interactions in the atmosphere. They’d also need to tell the difference between cosmic neutrinos from the Milky Way and ones from other sources.

“We do a lot of simulations. We take an idealized image of our detector and we say, ‘This is the response of our detector to this particle in this interaction.’ We simulate a response and then we compare that with our data … Where Bridges-2 comes in is [that] it simulates the light moving through the south polar ice coming from the neutrino interactions on Bridges-2’s GPUs, and then the spare CPU cycles can be used for anything from data analysis to particle generation.” — Benedikt Riedel, University of Wisconsin

Benedikt Riedel at the University of Wisconsin, a leading scientist in the IceCube Collaboration, oversaw the use of several systems to simulate how imperfections in the ice would affect the patterns of detection. Bridges-2 proved particularly adept at these simulations. Its ability to offer both powerful central processing units, or CPUs, and late-model graphical processing units, or GPUs, helped untangle the crazy particle showers expected, to show how they related to neutrinos passing through the ice sheet. The collaborators also used the large Frontera supercomputer at the Texas Advanced Computing Center, PSC’s partner in the ACCESS network of NSF-funded supercomputers.

Thanks in part to Bridges-2, the team was able to identify what patterns of detector activations in IceCube came from real cosmic neutrinos. The result was a map of our galaxy — the first such map using a new messenger other than electromagnetic waves. While the map is admittedly crude compared with the exquisite maps produced by visible-light- and infrared-detecting space telescopes, it provides the first opportunity to compare what the galaxy looks like using independent messengers. The team reported their results in the prestigious journal Science in July 2023.

Journal Link: Science

Source: Pittsburgh Supercomputing Center


Telescope Array detects second highest-energy cosmic ray ever



Newswise — In 1991, the University of Utah Fly’s Eye experiment detected the highest-energy cosmic ray ever observed. Later dubbed the Oh-My-God particle, the cosmic ray’s energy shocked astrophysicists. Nothing in our galaxy had the power to produce it, and the particle had more energy than was theoretically possible for cosmic rays traveling to Earth from other galaxies. Simply put, the particle should not exist.

The Telescope Array has since observed more than 30 ultra-high-energy cosmic rays, though none approaching the Oh-My-God-level energy. No observations have yet revealed their origin or how they are able to travel to the Earth.

On May 27, 2021, the Telescope Array experiment detected the second-highest extreme-energy cosmic ray. At 2.4 x 1020eV, the energy of this single subatomic particle is equivalent to dropping a brick on your toe from waist height. Led by the University of Utah (the U) and the University of Tokyo, the Telescope Array consists of 507 surface detector stations arranged in a square grid that covers 700 km(~270 miles2) outside of Delta, Utah in the state’s West Desert. The event triggered 23 detectors at the north-west region of the Telescope Array, splashing across 48 km2 (18.5 mi2). Its arrival direction appeared to be from the Local Void, an empty area of space bordering the Milky Way galaxy.

“The particles are so high energy, they shouldn’t be affected by galactic and extra-galactic magnetic fields. You should be able to point to where they come from in the sky,” said John Matthews, Telescope Array co-spokesperson at the U and co-author of the study. “But in the case of the Oh-My-God particle and this new particle, you trace its trajectory to its source and there’s nothing high energy enough to have produced it. That’s the mystery of this—what the heck is going on?” 

An animation replicating the timing and intensity of secondary particles hitting the Telescope Array surface detection.

In their observation that published on Nov. 24, 2023, in the journal Science, an international collaboration of researchers describe the ultra-high-energy cosmic ray, evaluate its characteristics, and conclude that the rare phenomena might follow particle physics unknown to science. The researchers named it the Amaterasu particle after the sun goddess in Japanese mythology. The Oh-My-God and the Amaterasu particles were detected using different observation techniques, confirming that while rare, these ultra-high energy events are real.

“These events seem like they’re coming from completely different places in the sky. It’s not like there’s one mysterious source,” said John Belz, professor at the U and co-author of the study. “It could be defects in the structure of spacetime, colliding cosmic strings. I mean, I’m just spit-balling crazy ideas that people are coming up with because there’s not a conventional explanation.”

Natural particle accelerators

Cosmic rays are echoes of violent celestial events that have stripped matter to its subatomic structures and hurled it through universe at nearly the speed of light. Essentially cosmic rays are charged particles with a wide range of energies consisting of positive protons, negative electrons, or entire atomic nuclei that travel through space and rain down onto Earth nearly constantly.

Cosmic rays hit Earth’s upper atmosphere and blasts apart the nucleus of oxygen and nitrogen gas, generating many secondary particles. These travel a short distance in the atmosphere and repeat the process, building a shower of billions of secondary particles that scatter to the surface. The footprint of this secondary shower is massive and requires that detectors cover an area as large as the Telescope Array. The surface detectors utilize a suite of instrumentation that gives researchers information about each cosmic ray; the timing of the signal shows its trajectory and the amount of charged particles hitting each detector reveals the primary particle’s energy.


Because particles have a charge, their flight path resembles a ball in a pinball machine as they zigzag against the electromagnetic fields through the cosmic microwave background. It’s nearly impossible to trace the trajectory of most cosmic rays, which lie on the low- to middle-end of the energy spectrum. Even high-energy cosmic rays are distorted by the microwave background. Particles with Oh-My-God and Amaterasu energy blast through intergalactic space relatively unbent. Only the most powerful of celestial events can produce them.   

“Things that people think of as energetic, like supernova, are nowhere near energetic enough for this. You need huge amounts of energy, really high magnetic fields to confine the particle while it gets accelerated,” said Matthews.

Ultra-high-energy cosmic rays must exceed 5 x 1019 eV. This means that a single subatomic particle carries the same kinetic energy as a major league pitcher’s fast ball and has tens of millions of times more energy than any human-made particle accelerator can achieve. Astrophysicists calculated this theoretical limit, known as the Greisen–Zatsepin–Kuzmin (GZK) cutoff, as the maximum energy a proton can hold traveling over long distances before the effect of interactions of the microwave background radiation take their energy. Known source candidates, such as active galactic nuclei or black holes with accretion disks emitting particle jets, tend to be more than 160 million light years away from Earth. The new particle’s 2.4 x 1020 eV and the Oh-My-God particle’s 3.2 x 1020 eV easily surpass the cutoff.

Researchers also analyze cosmic ray composition for clues of its origins. A heavier particle, like iron nuclei, are heavier, have more charge and are more susceptible to bending in a magnetic field than a lighter particle made of protons from a hydrogen atom. The new particle is likely a proton. Particle physics dictates that a cosmic ray with energy beyond the GZK cutoff is too powerful for the microwave background to distort its path, but back tracing its trajectory points towards empty space.

“Maybe magnetic fields are stronger than we thought, but that disagrees with other observations that show they’re not strong enough to produce significant curvature at these ten-to-the-twentieth electron volt energies,” said Belz. “It’s a real mystery.” 

Expanding the footprint 

The Telescope Array is uniquely positioned to detect ultra-high-energy cosmic rays. It sits at about 1,200 m (4,000 ft), the elevation sweet-spot that allows secondary particles maximum development, but before they start to decay. Its location in Utah’s West Desert provides ideal atmospheric conditions in two ways: the dry air is crucial because humidity will absorb the ultraviolet light necessary for detection; and the region’s dark skies are essential, as light pollution will create too much noise and obscure the cosmic rays.

Astrophysicists are still baffled by the mysterious phenomena. The Telescope Array is in the middle of an expansion that that they hope will help crack the case. Once completed, 500 new scintillator detectors will expand the Telescope Array will sample cosmic ray-induced particle showers across 2,900 km (1,100 mi), an area nearly the size of Rhode Island. The larger footprint will hopefully capture more events that will shed light on what’s going on.

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Unveiling the Mysteries of Cosmic Rays: Rare Ultra-High-Energy Particle Traced Beyond the Milky Way

Scientists detect rare ultra-high-energy particle from beyond the Milky Way, unraveling cosmic mysteries. Cosmic rays, space exploration, scientific breakthrough.



Artist’s illustration of ultra-high-energy cosmic ray astronomy to clarify extremely energetic phenomena. 

In a groundbreaking discovery, space scientists have made an astonishing observation that sheds light on the perplexing origins of cosmic rays. The findings, recently published in the renowned journal Science, unveil the detection of an exceptionally rare and ultra-high-energy particle believed to have journeyed to Earth from beyond our own Milky Way galaxy. This remarkable breakthrough opens up new avenues for understanding the vast cosmos and the forces that shape it.

Cosmic Rays: Nature’s Mysterious Messengers:
Cosmic rays are energetic particles that traverse the vast expanse of space before reaching our planet. While low-energy cosmic rays can be attributed to our sun, the presence of high-energy cosmic rays has long puzzled scientists. These highly charged particles are believed to originate from distant galaxies and extragalactic sources, but their precise origins have remained elusive.

A Particle of Unprecedented Energy:
The research team, composed of space scientists from around the world, has now detected an ultra-high-energy particle that has surpassed all previous records. The energy of this subatomic particle defies comprehension, described by the researchers as equivalent to dropping a brick on your toe from waist height. This astonishing particle rivals the famed “Oh-My-God” particle, which was first discovered in 1991 and held the title of the most energetic cosmic ray ever observed until now.

Unveiling the Cosmic Origins:
The detection of this rare ultra-high-energy particle provides a crucial piece of evidence in unraveling the cosmic puzzle. By analyzing its trajectory and energy signature, scientists can glean invaluable insights into the mechanisms and environments responsible for its creation. This breakthrough not only expands our understanding of cosmic rays but also offers a glimpse into the immense cosmic forces at play beyond our galactic home.

Advancing Scientific Knowledge:
The implications of this discovery extend far beyond the realm of cosmic rays. By studying these particles, scientists hope to unlock the mysteries of the universe, including the nature of dark matter, the formation of galaxies, and the evolution of cosmic structures. The identification of an ultra-high-energy particle from beyond the Milky Way represents a significant milestone in our quest for knowledge about the universe’s origins.

Collaboration and Technological Innovations:
The detection of this exceptional particle is the result of a collaborative effort among scientists utilizing cutting-edge observational and data analysis techniques. Advanced detectors and observatories, such as ground-based observatories and space-based telescopes, have played a pivotal role in capturing and analyzing the elusive cosmic rays. This research highlights the importance of international collaboration and technological advancements in pushing the boundaries of scientific exploration.

The discovery of an ultra-high-energy particle originating from beyond the Milky Way marks a monumental achievement in the field of space science. By unraveling the enigmatic origins of cosmic rays, scientists inch closer to understanding the vast cosmic tapestry that surrounds us. This remarkable finding paves the way for further discoveries, fueling our insatiable curiosity about the universe and reinforcing the importance of ongoing scientific exploration. As we continue to explore the depths of space, we can only wonder what other cosmic secrets await our discovery.




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Leonids Meteor Shower: Astronomy’s Spectacular Display or Disappointment?

Leonids: a renowned meteor shower in astronomy, but this year’s display may disappoint.



The Leonid meteor shower has long been renowned for its spectacular displays, etching its name in the annals of astronomy. While the shower is set to reach its peak on Saturday morning, expectations for this year’s event should be tempered. The Leonids have a rich history of meteor storms, with unforgettable shows observed in 1799, 1833, and 1966 when tens of thousands of meteors streaked across the sky every hour. More recent displays in 1999, 2001, and 2002 still impressed, though with fewer meteors per hour.

However, it is essential to dispel any notion that this year’s Leonids will rival the legendary shows of the past. Regrettably, many were led to believe that the same level of celestial fireworks could be expected annually. The truth is that the 2023 Leonids are likely to be underwhelming, with weak activity and prolonged periods without visible meteors.

So, while hopes may be high for a memorable meteor shower this weekend, it’s important to manage expectations and appreciate the natural fluctuations that make each celestial event unique. https://en.wikipedia.org/wiki/Leonids

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