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.
WHY IT’S IMPORTANT
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.
HOW PSC HELPED
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.
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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.
Habitable Zone Planets: How Scientists Search for Liquid Water Beyond Earth
Habitable zone planets: Scientists use the habitable zone to find planets that could host liquid water and life. Learn how planetary atmospheres and geology determine true habitability beyond Earth.
Some exoplanets, like the one shown in this illustration, may have atmospheres that could make them potentially suitable for life. NASA/JPL-Caltech via AP
Habitable Zone Planets: How Scientists Search for Liquid Water Beyond Earth
Morgan Underwood, Rice University When astronomers search for planets that could host liquid water on their surface, they start by looking at a star’s habitable zone. Water is a key ingredient for life, and on a planet too close to its star, water on its surface may “boil”; too far, and it could freeze. This zone marks the region in between. But being in this sweet spot doesn’t automatically mean a planet is hospitable to life. Other factors, like whether a planet is geologically active or has processes that regulate gases in its atmosphere, play a role. The habitable zone provides a useful guide to search for signs of life on exoplanets – planets outside our solar system orbiting other stars. But what’s in these planets’ atmospheres holds the next clue about whether liquid water — and possibly life — exists beyond Earth. On Earth, the greenhouse effect, caused by gases like carbon dioxide and water vapor, keeps the planet warm enough for liquid water and life as we know it. Without an atmosphere, Earth’s surface temperature would average around zero degrees Fahrenheit (minus 18 degrees Celsius), far below the freezing point of water. The boundaries of the habitable zone are defined by how much of a “greenhouse effect” is necessary to maintain the surface temperatures that allow for liquid water to persist. It’s a balance between sunlight and atmospheric warming. Many planetary scientists, including me, are seeking to understand if the processes responsible for regulating Earth’s climate are operating on other habitable zone worlds. We use what we know about Earth’s geology and climate to predict how these processes might appear elsewhere, which is where my geoscience expertise comes in.Picturing the habitable zone of a solar system analog, with Venus- and Mars-like planets outside of the ‘just right’ temperature zone.NASA
Why the habitable zone?
The habitable zone is a simple and powerful idea, and for good reason. It provides a starting point, directing astronomers to where they might expect to find planets with liquid water, without needing to know every detail about the planet’s atmosphere or history. Its definition is partially informed by what scientists know about Earth’s rocky neighbors. Mars, which lies just outside the outer edge of the habitable zone, shows clear evidence of ancient rivers and lakes where liquid water once flowed. Similarly, Venus is currently too close to the Sun to be within the habitable zone. Yet, some geochemical evidence and modeling studies suggest Venus may have had water in its past, though how much and for how long remains uncertain. These examples show that while the habitable zone is not a perfect predictor of habitability, it provides a useful starting point.
Planetary processes can inform habitability
What the habitable zone doesn’t do is determine whether a planet can sustain habitable conditions over long periods of time. On Earth, a stable climate allowed life to emerge and persist. Liquid water could remain on the surface, giving slow chemical reactions enough time to build the molecules of life and let early ecosystems develop resilience to change, which reinforced habitability. Life emerged on Earth, but continued to reshape the environments it evolved in, making them more conducive to life. This stability likely unfolded over hundreds of millions of years, as the planet’s surface, oceans and atmosphere worked together as part of a slow but powerful system to regulate Earth’s temperature. A key part of this system is how Earth recycles inorganic carbon between the atmosphere, surface and oceans over the course of millions of years. Inorganic carbon refers to carbon bound in atmospheric gases, dissolved in seawater or locked in minerals, rather than biological material. This part of the carbon cycle acts like a natural thermostat. When volcanoes release carbon dioxide into the atmosphere, the carbon dioxide molecules trap heat and warm the planet. As temperatures rise, rain and weathering draw carbon out of the air and store it in rocks and oceans. If the planet cools, this process slows down, allowing carbon dioxide, a warming greenhouse gas, to build up in the atmosphere again. This part of the carbon cycle has helped Earth recover from past ice ages and avoid runaway warming. Even as the Sun has gradually brightened, this cycle has contributed to keeping temperatures on Earth within a range where liquid water and life can persist for long spans of time. Now, scientists are asking whether similar geological processes might operate on other planets, and if so, how they might detect them. For example, if researchers could observe enough rocky planets in their stars’ habitable zones, they could look for a pattern connecting the amount of sunlight a planet receives and how much carbon dioxide is in its atmosphere. Finding such a pattern may hint that the same kind of carbon-cycling process could be operating elsewhere. The mix of gases in a planet’s atmosphere is shaped by what’s happening on or below its surface. One study shows that measuring atmospheric carbon dioxide in a number of rocky planets could reveal whether their surfaces are broken into a number of moving plates, like Earth’s, or if their crusts are more rigid. On Earth, these shifting plates drive volcanism and rock weathering, which are key to carbon cycling.Simulation of what space telescopes, like the Habitable Worlds Observatory, will capture when looking at distant solar systems.STScI, NASA GSFC
Keeping an eye on distant atmospheres
The next step will be toward gaining a population-level perspective of planets in their stars’ habitable zones. By analyzing atmospheric data from many rocky planets, researchers can look for trends that reveal the influence of underlying planetary processes, such as the carbon cycle. Scientists could then compare these patterns with a planet’s position in the habitable zone. Doing so would allow them to test whether the zone accurately predicts where habitable conditions are possible, or whether some planets maintain conditions suitable for liquid water beyond the zone’s edges. This kind of approach is especially important given the diversity of exoplanets. Many exoplanets fall into categories that don’t exist in our solar system — such as super Earths and mini Neptunes. Others orbit stars smaller and cooler than the Sun. The datasets needed to explore and understand this diversity are just on the horizon. NASA’s upcoming Habitable Worlds Observatory will be the first space telescope designed specifically to search for signs of habitability and life on planets orbiting other stars. It will directly image Earth-sized planets around Sun-like stars to study their atmospheres in detail.NASA’s planned Habitable Worlds Observatory will look for exoplanets that could potentially host life. Instruments on the observatory will analyze starlight passing through these atmospheres to detect gases like carbon dioxide, methane, water vapor and oxygen. As starlight filters through a planet’s atmosphere, different molecules absorb specific wavelengths of light, leaving behind a chemical fingerprint that reveals which gases are present. These compounds offer insight into the processes shaping these worlds. The Habitable Worlds Observatory is under active scientific and engineering development, with a potential launch targeted for the 2040s. Combined with today’s telescopes, which are increasingly capable of observing atmospheres of Earth-sized worlds, scientists may soon be able to determine whether the same planetary processes that regulate Earth’s climate are common throughout the galaxy, or uniquely our own. Morgan Underwood, Ph.D. Candidate in Earth, Environmental and Planetary Sciences, Rice University This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Beyond the habitable zone: Exoplanet atmospheres are the next clue to finding life on planets orbiting distant stars
The habitable zone is just the start. Scientists now focus on exoplanet atmospheres to find signs of life beyond Earth. Discover how carbon cycling, greenhouse gases, and NASA’s upcoming Habitable Worlds Observatory could reveal habitable worlds orbiting distant stars.
Some exoplanets, like the one shown in this illustration, may have atmospheres that could make them potentially suitable for life. NASA/JPL-Caltech via AP
Beyond the habitable zone: Exoplanet atmospheres are the next clue to finding life on planets orbiting distant stars
Morgan Underwood, Rice University When astronomers search for planets that could host liquid water on their surface, they start by looking at a star’s habitable zone. Water is a key ingredient for life, and on a planet too close to its star, water on its surface may “boil”; too far, and it could freeze. This zone marks the region in between. But being in this sweet spot doesn’t automatically mean a planet is hospitable to life. Other factors, like whether a planet is geologically active or has processes that regulate gases in its atmosphere, play a role. The habitable zone provides a useful guide to search for signs of life on exoplanets – planets outside our solar system orbiting other stars. But what’s in these planets’ atmospheres holds the next clue about whether liquid water — and possibly life — exists beyond Earth. On Earth, the greenhouse effect, caused by gases like carbon dioxide and water vapor, keeps the planet warm enough for liquid water and life as we know it. Without an atmosphere, Earth’s surface temperature would average around zero degrees Fahrenheit (minus 18 degrees Celsius), far below the freezing point of water. The boundaries of the habitable zone are defined by how much of a “greenhouse effect” is necessary to maintain the surface temperatures that allow for liquid water to persist. It’s a balance between sunlight and atmospheric warming. Many planetary scientists, including me, are seeking to understand if the processes responsible for regulating Earth’s climate are operating on other habitable zone worlds. We use what we know about Earth’s geology and climate to predict how these processes might appear elsewhere, which is where my geoscience expertise comes in.Picturing the habitable zone of a solar system analog, with Venus- and Mars-like planets outside of the ‘just right’ temperature zone.NASA
Why the habitable zone?
The habitable zone is a simple and powerful idea, and for good reason. It provides a starting point, directing astronomers to where they might expect to find planets with liquid water, without needing to know every detail about the planet’s atmosphere or history. Its definition is partially informed by what scientists know about Earth’s rocky neighbors. Mars, which lies just outside the outer edge of the habitable zone, shows clear evidence of ancient rivers and lakes where liquid water once flowed. Similarly, Venus is currently too close to the Sun to be within the habitable zone. Yet, some geochemical evidence and modeling studies suggest Venus may have had water in its past, though how much and for how long remains uncertain. These examples show that while the habitable zone is not a perfect predictor of habitability, it provides a useful starting point.
Planetary processes can inform habitability
What the habitable zone doesn’t do is determine whether a planet can sustain habitable conditions over long periods of time. On Earth, a stable climate allowed life to emerge and persist. Liquid water could remain on the surface, giving slow chemical reactions enough time to build the molecules of life and let early ecosystems develop resilience to change, which reinforced habitability. Life emerged on Earth, but continued to reshape the environments it evolved in, making them more conducive to life. This stability likely unfolded over hundreds of millions of years, as the planet’s surface, oceans and atmosphere worked together as part of a slow but powerful system to regulate Earth’s temperature. A key part of this system is how Earth recycles inorganic carbon between the atmosphere, surface and oceans over the course of millions of years. Inorganic carbon refers to carbon bound in atmospheric gases, dissolved in seawater or locked in minerals, rather than biological material. This part of the carbon cycle acts like a natural thermostat. When volcanoes release carbon dioxide into the atmosphere, the carbon dioxide molecules trap heat and warm the planet. As temperatures rise, rain and weathering draw carbon out of the air and store it in rocks and oceans. If the planet cools, this process slows down, allowing carbon dioxide, a warming greenhouse gas, to build up in the atmosphere again. This part of the carbon cycle has helped Earth recover from past ice ages and avoid runaway warming. Even as the Sun has gradually brightened, this cycle has contributed to keeping temperatures on Earth within a range where liquid water and life can persist for long spans of time. Now, scientists are asking whether similar geological processes might operate on other planets, and if so, how they might detect them. For example, if researchers could observe enough rocky planets in their stars’ habitable zones, they could look for a pattern connecting the amount of sunlight a planet receives and how much carbon dioxide is in its atmosphere. Finding such a pattern may hint that the same kind of carbon-cycling process could be operating elsewhere. The mix of gases in a planet’s atmosphere is shaped by what’s happening on or below its surface. One study shows that measuring atmospheric carbon dioxide in a number of rocky planets could reveal whether their surfaces are broken into a number of moving plates, like Earth’s, or if their crusts are more rigid. On Earth, these shifting plates drive volcanism and rock weathering, which are key to carbon cycling.Simulation of what space telescopes, like the Habitable Worlds Observatory, will capture when looking at distant solar systems.STScI, NASA GSFC
Keeping an eye on distant atmospheres
The next step will be toward gaining a population-level perspective of planets in their stars’ habitable zones. By analyzing atmospheric data from many rocky planets, researchers can look for trends that reveal the influence of underlying planetary processes, such as the carbon cycle. Scientists could then compare these patterns with a planet’s position in the habitable zone. Doing so would allow them to test whether the zone accurately predicts where habitable conditions are possible, or whether some planets maintain conditions suitable for liquid water beyond the zone’s edges. This kind of approach is especially important given the diversity of exoplanets. Many exoplanets fall into categories that don’t exist in our solar system — such as super Earths and mini Neptunes. Others orbit stars smaller and cooler than the Sun. The datasets needed to explore and understand this diversity are just on the horizon. NASA’s upcoming Habitable Worlds Observatory will be the first space telescope designed specifically to search for signs of habitability and life on planets orbiting other stars. It will directly image Earth-sized planets around Sun-like stars to study their atmospheres in detail.NASA’s planned Habitable Worlds Observatory will look for exoplanets that could potentially host life. Instruments on the observatory will analyze starlight passing through these atmospheres to detect gases like carbon dioxide, methane, water vapor and oxygen. As starlight filters through a planet’s atmosphere, different molecules absorb specific wavelengths of light, leaving behind a chemical fingerprint that reveals which gases are present. These compounds offer insight into the processes shaping these worlds. The Habitable Worlds Observatory is under active scientific and engineering development, with a potential launch targeted for the 2040s. Combined with today’s telescopes, which are increasingly capable of observing atmospheres of Earth-sized worlds, scientists may soon be able to determine whether the same planetary processes that regulate Earth’s climate are common throughout the galaxy, or uniquely our own. Morgan Underwood, Ph.D. Candidate in Earth, Environmental and Planetary Sciences, Rice University This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Interstellar Comet 3I/ATLAS Surprises Astronomers with Unusual Green Glow and Solar-Pointing Jets
Astronomers are studying interstellar comet 3I/ATLAS, a rare green-glowing visitor with solar-pointing jets and a high carbon dioxide ratio, offering new insights into how comets form beyond our Solar System.
A blazing interstellar object streaks across the night sky as a telescope looks on, highlighting the growing mystery surrounding 3I/ATLAS.
Astronomers are keeping a close eye on 3I/ATLAS, the third known interstellar comet to pass through our Solar System — and it’s turning out to be one of the most intriguing cosmic visitors yet. New observations reveal that the comet glows a faint green hue and displays several active jets, including one that oddly points toward the Sun, forming a rare “anti-tail” structure.
According to data from NASA’s James Webb Space Telescope, 3I/ATLAS contains an unusually high ratio of carbon dioxide to water vapor, indicating it may have formed in a much colder and more distant environment than our Solar System. Currently drifting through the constellation Virgo, the comet continues to brighten rapidly as it nears its closest approach to Earth in December 2025, though it will remain safely millions of miles away. Scientists say studying 3I/ATLAS could offer valuable clues about how comets form around other stars — and what materials might exist beyond our solar neighborhood.
