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ACCESS Scholar: Kate Anderson

ACCESS Scholar, Kate Anderson


October 1, 2024
Above: Kate Anderson

Undergraduate Kate Anderson has her sights set far, another planet to be exact. After a year of research in the ACCESS Scholars program, she is one step closer to her dream of becoming a NASA astronaut. 

Anderson grew up in Las Vegas, Nevada, and had a passion for science, astronomy specifically, from a young age. She says that ACCESS was what initially drew her to the U, and ultimately what made her decide to major in physics and chemistry. The ACCESS scholarship is designed to advance belonging in STEM by engaging first-year students with research and helping them develop a community within the college.

Like many alumni of the program, ACCESS strongly shaped Anderson’s first year experience. She contributed to a project in Assistant Professor Yao-Yuan Mao’s astrophysics lab. Anderson gathered data with code to locate isolated, low-mass galaxies near the Milky Way that might provide clues to the origin of our universe. 

“Some of these galaxies are so isolated from the Milky Way that they have had little to no interaction with other galaxies since their creation. Because of that, they still have a lot of the properties of the very early universe. I was just trying to find the precursor to the bigger question” explains Anderson. 

This hands-on research experience through ACCESS helped Anderson earn a NASA Space Grant Consortium Scholarship, an additional boost on her path to becoming an astronaut. 

Anderson’s dream of voyaging to another planet to do true astrophysics “fieldwork” is supported by a plan that has been in the works since well before she stepped foot on campus. “I decided I wanted to be an astronaut and worked backwards,” she says. 

NASA astronauts either have a science or military background. Anderson thought “why not both?”. This motivated her to join the Air Force ROTC in addition to her academic obligations with the hope of becoming a pilot. This way, she can command the spaceship as well as handle the science. 

“NASA actually posted applications for astronauts a couple months ago. I was devastated that I couldn't apply now,” says Anderson. Though the journey ahead is long, this budding scientist and future space traveler has a lot to look forward to in her next few years at the U. Anderson is excited about starting  new research projects, taking observational astronomy, and spending time with her friends, many of whom she met through ACCESS. 

By Lauren Wigod

How special is the Milky Way Galaxy?  

How special is the Milky Way Galaxy?


September 25, 2024

Above: A mosaic of the satellite galaxies across the Milky Way-like systems that the SAGA team has surveyed. The mages are sorted by their luminosity from left to right. Credit: Yao-Yuan Mao (Utah), with images from the DESI Legacy Surveys Sky Viewer

A “saga” about 101 galaxies like the Milky Way and their companions

Is our home galaxy, the Milky Way Galaxy, a special place? A team of scientists started a journey to answer this question more than a decade ago. Commenced in 2013, the Satellites Around Galactic Analogs (SAGA) Survey studies galaxy systems like the Milky Way. Now, the SAGA Survey just published three new research articles that provide us with new insights into the uniqueness of our own Milky Way Galaxy after completing the census of 101 satellite systems similar to the Milky Way’s.   

These “satellites” are smaller galaxies in both mass and size which orbit a larger galaxy, usually called the host galaxy. Just as with smaller satellites that orbit the Earth, these satellite galaxies are captured by the gravitational pull of the massive host galaxy and its surrounding dark matter. The Milky Way Galaxy is the host galaxy of several satellite galaxies, of which the two largest are the Large and Small Magellanic Clouds (LMC and SMC). While LMC and SMC are visible to the naked eye from the Southern Hemisphere, there are many other fainter satellite galaxies orbiting around the Milky Way Galaxy that can only be observed with a large telescope.  

The goal of the SAGA Survey is to characterize satellite systems around other host galaxies that have similar stellar masses as the Milky Way Galaxy. Yao-Yuan Mao, a University of Utah faculty member in the Department of Physics and Astronomy, is co-leading the SAGA Survey with Marla Geha at Yale University and Risa Wechsler at Stanford University. Mao is the lead author of the first article in the series of three that have all been accepted by the Astrophysical Journal. This series of articles reports on the SAGA Survey’s latest findings and makes the survey data available to other researchers worldwide.  

 An outlier galaxy? 

An image of a Milky Way-like galaxy and its system of satellite galaxies. The SAGA survey identified six small satellite galaxies in orbit around this Milky Way analog. Credit: Yasmeen Asali (Yale), with images from the DESI Legacy Surveys Sky Viewer https://www.legacysurvey.org/acknowledgment/

 In the first study led by Mao, the researchers highlighted 378 satellite galaxies identified across 101 Milky Way-mass systems. The number of confirmed satellites per system ranged from zero to 13 — compared to four satellites for the Milky Way. While the number of satellite galaxies in the Milky Way system is on par with the other Milky Way-mass systems, “the Milky Way appears to host fewer satellites if you consider the existence of the LMC,” Mao said. The SAGA Survey has found that systems with a massive satellite like the LMC tend to have a higher total number of satellites, and our Milky Way seems to be an outlier in this regard. 

An explanation for this apparent difference between the Milky Way and the SAGA systems is the fact that the Milky Way has only acquired the LMC and SMC quite recently, compared with the age of the universe). The SAGA article explains that if the Milky Way Galaxy is an older, slightly less massive host with the recently added LMC and SMC, one would then expect a lower number of satellites in the Milky Way system not counting other smaller satellites that LMC/SMC might have brought in.  

This result demonstrates the importance of understanding the interaction between the host galaxy and the satellite galaxies, especially when interpreting what we learn from observing the Milky Way. Ekta Patel, a NASA Hubble Postdoctoral Fellow at the U but not part of the SAGA team, studies the orbital histories of Milky Way satellites. After learning about the SAGA results, Patel said, “Though we cannot yet study the orbital histories of satellites around SAGA hosts, the latest SAGA data release includes a factor of ten more Milky Way-like systems that host an LMC-like companion than previously known. This huge advancement provides more than 30 galaxy ecosystems to compare with our own, and will be especially useful in understanding the impact of a massive satellite analogous to the LMC on the systems they reside in.”  

Why do galaxies stop forming stars? 

The second SAGA study of the series is led by Geha, and it explores whether these satellite galaxies are still forming stars. Understanding the mechanisms that would stop the star formation in these small galaxies is an important question in the field

Yao-Yuan Mao

of galaxy evolution. The researchers found, for example, that satellite galaxies located closer to their host galaxy were more likely to have their star formation “quenched,” or suppressed. This suggests that environmental factors help shape the life cycle of small satellite galaxies.  

The third new study is led by Yunchong (Richie) Wang, who obtained his PhD with Wechsler. This study uses the SAGA Survey results to improve existing theoretical models of galaxy formation. Based on the number of quenched satellites in these Milky Way-mass systems, this model predicts quenched galaxies should also exist in more isolated environments — a prediction that should be possible to test in the coming years with other astronomical surveys such as the Dark Energy Spectroscopic Instrument Survey.  

Gift to the astronomy community 

In addition to these exciting results that will enhance our understanding of galaxy evolution, the SAGA Survey team also brings a gift to the astronomy community. As part of this series of studies, the SAGA Survey team published new distance measurements, or redshifts, for about 46,000 galaxies. “Finding these satellite galaxies is like finding needles in a haystack. We had to measure the redshifts for hundreds of galaxies to just identify one satellite galaxy,” Mao said. “These new galaxy redshifts will enable the astronomy community to study a wide range of topics beyond the satellite galaxies.”  

The SAGA Survey was supported in part by the National Science Foundation and the Heising-Simons Foundation. Other authors of these three SAGA studies include Yasmeen Asali, Erin Kado-Fong, Nitya Kallivayalil, Ethan Nadler, Erik Tollerud, Benjamin Weiner, Mia de los Reyes, John F. Wu, Tom Abel, and Peter Behroozi. 

By David Pace

A once-in-a-career discovery: the black hole at Omega Centauri’s core

A once-in-a-career discovery: the black hole at Omega Centauri’s core


July 11, 2024
Above: The likely position of Omega Centauri star cluster’s intermediate black hole. Closest panel zooms to the system.
PHOTO CREDIT: ESA/HUBBLE & NASA, M. HÄBERLE (MPIA)

Omega Centauri is a spectacular collection of 10 million stars, visible as a smudge in the night sky from Southern latitudes.

Through a small telescope, it looks no different from other so-called globular clusters; a spherical stellar collection so dense towards the center that it becomes impossible to distinguish individual stars. But a new study, led by researchers from the University of Utah and the Max Planck Institute for Astronomy, confirms what astronomers had argued about for over a decade: Omega Centauri contains a central black hole.The black hole appears to be the missing link between its stellar and supermassive kin—stuck in an intermediate stage of evolution, it is considerably less massive than typical black holes in the centers of galaxies. Omega Centauri seems to be the core of a small, separate galaxy whose evolution was cut short when it was swallowed by the Milky Way.

“This is a once-in-a-career kind of finding. I’ve been excited about it for nine straight months. Every time I think about it, I have a hard time sleeping,” said Anil Seth, associate professor of astronomy at the U and co-principal investigator (PI) of the study. “I think that extraordinary claims require extraordinary evidence. This is really, truly extraordinary evidence.” A clear detection of this black hole had eluded astronomers until now. The overall motions of the stars in the cluster showed that there was likely some unseen mass near its center, but it was unclear if this was an intermediate-mass black hole or just a collection of the stellar black holes. Maybe there was no central black hole at all.

A medium Level panel zoom of the Omega Centauri star cluster’s intermediate black hole likely position. PHOTO CREDIT: ESA/HUBBLE & NASA, M. HÄBERLE (MPIA)

“Previous studies had prompted critical questions of ‘So where are the high-speed stars?’ We now have an answer to that, and the confirmation that Omega Centauri contains an intermediate-mass black hole. At about 18,000 light-years, this is the closest known example for a massive black hole,” said Nadine Neumayer, a group leader at the Max Planck Institute and PI of the study. For comparison, the supermassive black hole in the center of the Milky Way is about 27,000 light-years away.

A range of black hole masses

In astronomy, black holes come in different mass ranges. Stellar black holes, between one and a few dozen solar masses, are well known, as are the supermassive black holes with masses of millions or even billions of suns. Our current picture of galaxy evolution suggests that the earliest galaxies should have had intermediate-sized central black holes that would have grown over time, gobbling up smaller galaxies done or merging with larger galaxies.

Such medium-sized black holes are notoriously hard to find. Although there are promising candidates, there has been no definite detection of such an intermediate-mass black hole—until now.

“There are black holes a little heavier than our sun that are like ants or spiders—they’re hard to spot, but kind of everywhere throughout the universe. Then you’ve got supermassive black holes that are like Godzilla in the centers of galaxies tearing things up, and we can see them easily,” said Matthew Whittaker, an undergraduate student at the U and co-author of the study. “Then these intermediate-mass black holes are kind of on the level of Bigfoot. Spotting them is like finding the first evidence for Bigfoot—people are going to freak out.”

Read more about the Discovery @TheU.

Read more about the story at NASA, Deseret News, ABC4 Utah and ESA/Hubble releases.

Neutrino Oscillation Research Advances

Neutrino Oscillation Research Advances


July 9, 2024
Above: A Layout of IceCube Lab depth compared to the height of the Eiffel Tower.

In the world of particle physics, electrical charges define the terms. While electrons have a negative charge, the appropriately named “positron" has a positive charge. But then there are neutrinos which have no charge at all.

Neutrinos are also incredibly small and light. They have some mass, but not much and they rarely interact with other matter. They come in three types or "flavors": electron, muon, and tau.

Cosmic rays travel through space then crash into the earth's atmosphere and produce  air showers that Include neutrinos and many other types of particles. When neutrinos are produced and start traveling, they can change from one flavor to another. The atmospheric neutrinos are then detected by DeepCore, a denser array of sensors in the center of the IceCube detector at the South Pole.This process is called neutrino oscillation and the IceCube Detector, a massive neutrino detector buried deep in the ice at the South Pole, has a special area called DeepCore that can detect lower-energy neutrinos.

Scientists at the IceCube Neutrino Observatory in Antarctica have made a breakthrough in measuring neutrinos. Using advanced computer techniques, they've achieved the most precise measurements to date of how these particles change as they travel through space, helping us understand fundamental properties of the universe that could lead to new discoveries in physics.

Shiqi Yu

Shiqi Yu, a research assistant professor in the Department of Physics & Astronomy at the University of Utah and others who published their findings recently in Physical Review Letters analyzed data from over 150,000 neutrino events collected over nine years (2012-2021). They used advanced computer programs called convolutional neural networks (CNNs) to process this data. The team made the most precise measurements ever of two important properties related to neutrino oscillation: Delta m²₃₂ and sin²(θ₂₃). These numbers help describe how neutrinos change as they travel.

“We also carefully studied the systematic uncertainties that arise from our imperfect knowledge of our models and chose some to use as free nuisance parameters that fit together with the physics parameters for our data,” says Yu.

Using CNNs, which use three-dimensional data for image classification, Yu and co-lead of the study Jessie Micallef first developed use cases for the CNNs to focus on the DeepCore region and trained them to reconstruct different properties of particle interactions in the detector. They then used the CNN reconstructions to select qualified neutrino interactions that happened in or near the DeepCore region to produce a neutrino-dominated dataset with well-reconstructed energies and zenith angles.

Jessie Micallef

Yu notes that the CNN-reconstructed analysis-level dataset is already being used for other neutrino oscillation analyses, such as determining the neutrino mass ordering and non-standard neutrino interactions and for atmospheric tau neutrino appearance analyses.

“The atmospheric neutrino dataset from DeepCore exhibits relatively high energies in the oscillation analyses, which is unique compared to existing accelerator-based experiments,” says Yu. “Given our dataset and independent analysis, it is interesting to see agreement and consistency in physics parameter measurements.”

This research helps confirm and refine our understanding of how neutrinos — fundamental particles that can tell us a lot about the universe — behave. The techniques developed here, animated by machine learning, can be used in future studies to learn even more about neutrinos and the universe. Those future studies will be informed by IceCube which is planning an upgrade in 2025-2026 that will allow for even more detailed measurements of neutrinos.

By studying neutrino detection and the phenomenon of neutrino oscillation, scientists like Shiqi Yu hope to answer big questions about the nature of matter, energy and the cosmos.

Read the May 2024

Spectrum 2023

Spectrum 2023


Synthesis 2024

SRI inaugural cohort, the U in biotech and stories from throughout the College of Science

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Aftermath 2024

The official magazine of the U Department of Mathematics.

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Common Ground 2023

The official magazine of the U Department of Mining Engineering.

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Down to Earth 2023

The official magazine of the U Department of Geology & Geophysics.

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Our DNA 2023

The official magazine of the School of Biological Sciences at the University of Utah.

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Catalyst 2023

The official magazine of the Department of Chemistry at the University of Utah.

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Synthesis 2023

Wilkes Center, Applied Science Project and stories from throughout the merged College.

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Aftermath Summer 2023

Anna Tang Fulbright Scholar, Tommaso de Fernex new chair, Goldwater Scholars, and more.

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Air Currents 2023

Celebrating 75 Years, The Great Salt Lake, Alumni Profiles, and more.

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Spectrum 2022

Explosive neutron stars, Utah meteor, fellows of APS, and more.

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Aftermath 2022

Arctic adventures, moiré magic, Christopher Hacon, and more.

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Our DNA 2022

Chan Yul Yoo, Sarmishta Diraviam Kannan, and more.

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Spectrum 2022

Black Holes, Student Awards, Research Awards, LGBT+ physicists, and more.

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Aftermath 2022

Student awards, Faculty Awards, Fellowships, and more.

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Our DNA 2022

Erik Jorgensen, Mark Nielsen, alumni George Seifert, new faculty, and more.

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Notebook 2022

Student stories, NAS members, alumni George Seifert, and Convocation 2022.

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Discover 2021

Biology, Chemistry, Math, and Physics Research, SRI Update, New Construction.

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Our DNA 2021

Multi-disciplinary research, graduate student success, and more.

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Aftermath 2021

Sound waves, student awards, distinguished alumni, convocation, and more.

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Spectrum 2021

New science building, faculty awards, distinguished alumni, and more.

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Notebook 2021

Student awards, distinguished alumni, convocation, and more.

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Spectrum 2021

Student awards, distinguished alumni, convocation, and more.

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Aftermath 2021

Sound waves, student awards, distinguished alumni, convocation, and more.

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Our DNA 2021

Plant pandemics, birdsong, retiring faculty, and more.

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Discover 2020

Biology, Chemistry, Math, and Physics Research, Overcoming Covid, Lab Safety.

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AfterMath 2020

50 Years of Math, Sea Ice, and Faculty and Staff recognition.

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Our DNA 2020

E-birders, retiring faculty, remote learning, and more.

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Spectrum 2020

3D maps of the Universe, Perovskite Photovoltaics, and Dynamic Structure in HIV.

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Notebook 2020

Convocation, Alumni, Student Success, and Rapid Response Research.

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Our DNA 2020

Stories on Fruit Flies, Forest Futures and Student Success.

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Catalyst 2020

Transition to Virtual, 2020 Convocation, Graduate Spotlights, and Awards.

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Spectrum 2020

Nuclear Medicine, PER Programs, and NSF grant for Quantum Idea Incubator.

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Discover 2019

Science Research Initiative, College Rankings, Commutative Algebra, and more.

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Spectrum 2019

Nuclear Medicine, PER Programs, and NSF grant for Quantum Idea Incubator.

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Notebook 2019

The New Faces of Utah Science, Churchill Scholars, and Convocation 2019.

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Catalyst 2019

Endowed Chairs of Chemistry, Curie Club, and alumnus: Victor Cee.

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Our DNA 2019

Ants of the World, CRISPR Scissors, and Alumni Profile - Nikhil Bhayani.

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Catalyst 2019

Methane-Eating Bacteria, Distinguished Alumni, Student and Alumni profiles.

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Spectrum 2019

Featured: Molecular Motors, Churchill Scholar, Dark Matter, and Black Holes.

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Our DNA 2019

Featured: The Startup Life, Monica Gandhi, Genomic Conflicts, and alumna Jeanne Novak.

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AfterMath 2018

Featured: A Love for Puzzles, Math & Neuroscience, Number Theory, and AMS Fellows.

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Discover 2018

The 2018 Research Report for the College of Science.

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Spectrum 2018

Featured: Dark Matter, Spintronics, Gamma Rays and Improving Physics Teaching.

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Catalyst 2018

Featured: Ming Hammond, Jack & Peg Simons Endowed Professors, Martha Hughes Cannon.

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1st detection of heavy element from star merger

first detection of heavy element from star merger

 

“We only know of a handful of kilonovas with any certainty, and this is only the second one for which we have such detailed spectral information” said Tanmoy Laskar, assistant professor at the University of Utah, of the first detection of we have of heavy element from a star merger.

Tanmoy Laskar. Banner photo (above): This image from Webb’s NIRCam (Near-Infrared Camera) instrument highlights GRB 230307A’s kilonova and its former home galaxy among their local environment of other galaxies and foreground stars. The neutron stars were kicked out of their home galaxy and traveled the distance of about 120,000 light-years, approximately the diameter of the Milky Way galaxy, before finally merging several hundred million years later. CREDIT: NASA, ESA, CSA, STSCI, ANDREW LEVAN (IMAPP, WARW)

Tanmoy Laskar and colleagues has used multiple space and ground-based telescopes, including NASA’s James Webb Space Telescope, NASA’s Fermi Gamma-ray Space Telescope, and NASA’s Neil Gehrels Swift Observatory, to observe an exceptionally bright gamma-ray burst, GRB 230307A, and identify the neutron star merger that generated an explosion that created the burst. Webb also helped scientists detect the chemical element tellurium in the explosion’s aftermath.

“Just over 150 years since Dmitri Mendeleev wrote down the periodic table of elements, we are now finally in the position to start filling in those last blanks of understanding where everything was made, thanks to Webb,” said Andrew Levan of Radboud University in the Netherlands and the University of Warwick in the UK, lead author of the study.

While neutron star mergers have long been theorized as being the ideal “pressure cookers” to create some of the rarer elements substantially heavier than iron, astronomers have previously encountered a few obstacles in obtaining solid evidence.

Kilonovas are extremely rare, making it difficult to observe these events. Short gamma-ray bursts (GRBs), traditionally thought to be those that last less than two seconds, can be byproducts of these infrequent merger episodes. In contrast, long gamma-ray bursts may last several minutes and are usually associated with the explosive death of a massive star.

The case of GRB 230307A is particularly remarkable. First detected by NASA’s Fermi Gamma-ray Space Telescope in March, it is the second brightest GRB observed in over 50 years of observations, about 1,000 times brighter than a typical gamma-ray burst that Fermi observes. It also lasted for 200 seconds, placing it firmly in the category of long duration gamma-ray bursts, despite its different origin.

“This burst is way into the long category. It’s not near the border. But it seems to be coming from a merging neutron star,” added Eric Burns, a co-author of the paper and member of the Fermi team at Louisiana State University.

Read the full article by Lisa Potter in @TheU.  Adapted from NASA Webb Space Telescope.

Why Scientists Haven’t Solved the Mystery of the OMG Particle

Solving The Mystery Of The 'OMG Particle'

 

Below the snow-covered peaks of the Andes Mountains, among scattered rocks and the scrub of prairie bushes, there sits at this very moment a 12-ton polyethylene tank holding 3,000 gallons of pure water.

 

All around it, spread out in every direction over an area nearly the size of Rhode Island, are 1,599 more such tanks, each identical to the first. These lonely sentinels have their eyes on the sky, patiently observing what human eyes cannot in the hopes of solving a mystery that began on another continent and more than three decades prior — a mystery that started with the Oh-My-God event.

It was the night of October 15, 1991. The University of Utah had set up an experimental observatory called the Fly's Eye in the isolation of Dugway Proving Ground, a sprawling 800,000-acre tract of land used by the U.S. Army to test biological and chemical weapons since the 1940s. On that night the Fly's Eye detected something called an air shower, a miles-long explosion of streaming particles invisible to the human eye and caused by high-energy interactions in the upper atmosphere. Each of the telescope’s detectors were designed to point at a different part of the field of view, in a similar way to insects’ compound eyes. It was this that earned the telescope its name. “We were hoping we might pick up something really unusual,” says David Kieda at the University of Utah, who worked on the telescope at the time. (Read more about the Fly's Eye Array here.)

Scientists looked at the data they'd collected and worked backward to deduce the properties of the space-borne particle that led to the air shower. The results weren't just shocking — they were thought to be impossible. They called their discovery the Oh-My-God particle.

While the Oh-My-God particle still remains the most energetic cosmic ray ever detected, a handful of others in the off-the-scales range have been observed in the years since, confirming that it wasn't a miscalculation or instrumentation failure, but in fact a real event. This is why 1,600 giant water-filled tanks have been installed in a grid formation across 3,000 square kilometers of the arid Mendoza region of Argentina. These are the specialized detectors of the Pierre Auger Observatory, forming an array designed to capture evidence of other extremely high-energy cosmic rays. "The quest for identifying the sources of the most energetic particles in the Universe continues," says Carsten Rott, chair of the Department of Physics & Astronomy at the U. "[But] not only at the Auger detector in Argentina, but also right here in Utah with the Telescope Array experiment."

 

Read the full story by DAVID ROSSIAKY in Slash Gear.

Sky Survey Data Releases 2 Million Stellar Objects

The universe is big, and it’s getting bigger.

To study dark energy, the mysterious force behind the accelerating expansion of our universe, scientists are using the Dark Energy Spectroscopic Instrument (DESI) to map nearly 40 million galaxies, quasars and stars. Today, the collaboration publicly released its first batch of data, with nearly 2 million objects for researchers to explore.

The 80-terabyte data set comes from 2,480 exposures taken over six months during the experiment’s “survey validation” phase in 2020 and 2021. Between turning the instrument on and beginning the official science run, researchers made sure their plan for using the telescope would meet their science goals—for example, by checking how long it took to observe galaxies of different brightness, and by validating the selection of stars and galaxies to observe.

“The fact that DESI works so well, and that the amount of science-grade data it took during survey validation is comparable to previous completed sky surveys, is a monumental achievement,” said Nathalie Palanque-Delabrouille, co-spokesperson for DESI and a scientist at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), which manages the experiment. “This milestone shows that DESI is a unique spectroscopic factory whose data will not only allow the study of dark energy but will also be coveted by the whole scientific community to address other topics, such as dark matter, gravitational lensing and galactic morphology.”

Kyle Dawson

DESI uses 5,000 robotic positioners to move optical fibers that capture light from objects millions or billions of light-years away. It is the most powerful multi-object survey spectrograph in the world, able to measure light from more than 100,000 galaxies in one night. That light tells researchers how far away an object is, building a 3-D cosmic map.

“This new sample represents the first science-quality data taken with this powerful new instrument. These survey-validation data are better quality and provide spectra and classification of a wider range of stars, galaxies and quasars than the data we expect in the main five-year program,” said Professor Kyle Dawson. Dawson of the University of Utah was one of the two primary leads of the survey validation effort and is also DESI co-spokesperson.  “We have learned from these data how to build the most effective cosmology program.”

Read the entire article in @TheU.

U Astronomy, New AURA Member

Banner photo by Gail Zasowski

The Association of Universities for Astronomy (AURA) is pleased to welcome two new member institutions: the University of Utah and the University of California at Los Angeles (UCLA). Both institutions’ applications to join AURA were approved by AURA’s Member Representatives at its April annual meeting in Tucson, Arizona.

University of Utah astronomy

Established in 1850, the University of Utah is the flagship university of the state. A community of students, staff and scholars, the University of Utah—affectionately called “the U”—is dedicated to the advancement of knowledge through innovative research; the education of future citizens, professionals and leaders; and scholarly and creative pursuits that preserve and broaden our understanding of the human condition. The U prepares students for leadership roles in Utah, the country and the world. Located in one of the darkest states in the nation, housing the Consortium for Dark Sky Studies and launching the first-ever minor in dark sky studies in the U.S., the U is a leader in exploring the impacts of artificial light at night and the loss of our night skies through a broad range of disciplines.

The University of Utah’s Department of Physics & Astronomy in the College of Science is committed to pursuing key science questions within an inclusive academic community; to training and diversifying the next generation of researchers, educators and technology workforce leaders; and to inspiring an appreciation for knowledge in students and the wider community.

Read the full story of the Department’s induction into AURA in @TheU

Extraordinary Black Hole

A Different Kind of Black Hole


Astronomers discovered a black hole unlike any other. At one hundred thousand solar masses, it is smaller than the black holes we have found at the centers of galaxies but bigger than the black holes that are born when stars explode. This makes it one of the only confirmed intermediate-mass black holes, an object that has long been sought by astronomers.

Anil Seth

“We have very good detections of the biggest, stellar-mass black holes up to 100 times the size of our sun, and supermassive black holes at the centers of galaxies that are millions of times the size of our sun, but there aren’t any measurements of black between these. That’s a large gap,” said senior author Anil Seth, associate professor of astronomy at the University of Utah and co-author of the study. “This discovery fills the gap.”

The black hole was hidden within B023-G078, an enormous star cluster in our closest neighboring galaxy Andromeda. Long thought to be a globular star cluster, the researchers argue that B023-G078 is instead a stripped nucleus. Stripped nuclei are remnants of small galaxies that fell into bigger ones and had their outer stars stripped away by gravitational forces. What’s left behind is a tiny, dense nucleus orbiting the bigger galaxy and at the center of that nucleus, a black hole.

“Previously, we’ve found big black holes within massive, stripped nuclei that are much bigger than B023-G078. We knew that there must be smaller black holes in lower mass stripped nuclei, but there’s never been direct evidence,” said lead author Renuka Pechetti of Liverpool John Moores University, who started the research while at the U. “I think this is a pretty clear case that we have finally found one of these objects.”

The study published on Jan. 11, 2022, in The Astrophysical Journal.

A decades-long hunch

B023-G078 was known as a massive globular star cluster—a spherical collection of stars bound tightly by gravity. However, there had only been a single observation of the object that determined its overall mass, about 6.2 million solar masses. For years, Seth had a feeling it was something else.

“I knew that the B023-G078 object was one of the most massive objects in Andromeda and thought it could be a candidate for a stripped nucleus. But we needed data to prove it. We’d been applying to various telescopes to get more observations for many, many years and my proposals always failed,” said Seth. “When we discovered a supermassive black hole within a stripped nucleus in 2014, the Gemini Observatory gave us the chance to explore the idea.”

A wide-field image of M31 with the red box and inset showing the location and image of B023-G78 where the black hole was found.

With their new observational data from the Gemini Observatory and images from the Hubble Space Telescope, Pechetti, Seth and their team calculated how mass was distributed within the object by modeling its light profile. A globular cluster has a signature light profile that has the same shape near the center as it does in the outer regions. B023-G078 is different. The light at the center is round and then gets flatter moving outwards. The chemical makeup of the stars changes too, with more heavy elements in the stars at the center than those near the object’s edge.

“Globular star clusters basically form at the same time. In contrast, these stripped nuclei can have repeated formation episodes, where gas falls into the center of the galaxy, and forms stars. And other star clusters can get dragged into the center by the gravitational forces of the galaxy,” said Seth. “It’s kind of the dumping ground for a bunch of different stuff. So, stars in stripped nuclei will be more complicated than in globular clusters. And that’s what we saw in B023-G078.”

The researchers used the object’s mass distribution to predict how fast the stars should be moving at any given location within the cluster and compared it to their data. The highest velocity stars were orbiting around the center. When they built a model without including a black hole, the stars at the center were too slow compared their observations. When they added the black hole, they got speeds that matched the data. The black hole adds to the evidence that this object is a stripped nucleus.

“The stellar velocities we are getting gives us direct evidence that there’s some kind of dark mass right at the center,” said Pechetti. “It’s very hard for globular clusters to form big black holes. But if it’s in a stripped nucleus, then there must already be a black hole present, left as a remnant from the smaller galaxy that fell into the bigger one.”

The researchers are hoping to observe more stripped nuclei that may hold more intermediate-mass black holes. These are an opportunity to learn more about the black hole population at the centers of low-mass galaxies, and to learn about how galaxies are built up from smaller building blocks.

“We know big galaxies form generally from the merging of smaller galaxies, but these stripped nuclei allow us to decipher the details of those past interactions,” said Seth.

Other authors include Sebastian Kamann of the Liverpool John Moores University; Nelson Caldwell, Harvard-Smithsonian Center for Astrophysics; Jay Strader, Michigan State University; Mark den Brok, Leibniz-Institut für Astrophysik Potsdam; Nora Luetzgendorf, European Space Agency; Nadine Neumayer, Max Planck Institüt für Astronomie; and Karina Voggel, Observatoire astronomique de Strasbourg.

- by Lisa Potter, published in @theU and the Deseret News

 

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