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The collapse and subsequent explosion of a massive star: B.O.A.T.

The collapse and explosion of a massive star: B.O.A.T.


April 19, 2024

Above: Artist’s visualization of GRB 221009A showing the narrow relativistic jets (emerging from a central black hole) that gave rise to the gamma-ray burst and the expanding remains of the original star ejected via the supernova explosion. CREDIT: AARON M. GELLER / NORTHWESTERN / CIERA / IT RESEARCH COMPUTING AND DATA SERVICES

In October 2022, an international team of researchers, including University of Utah astrophysicist Tanmoy Laskar, observed the brightest gamma-ray burst (GRB) ever recorded, GRB 221009A. Now, physicists have confirmed that the phenomenon responsible for the historic burst — dubbed the B.O.A.T. (“brightest of all time”) — is the collapse and subsequent explosion of a massive star.

Tanmoy Laskar, assistant professor, Department of Physics & Astronomy, University of Utah

The team discovered the explosion, or supernova, using NASA’s James Webb Space Telescope (JWST).

While this discovery solves one mystery, another mystery deepens. The researchers speculated that evidence of heavy elements, such as platinum and gold, might reside within the newly uncovered supernova. The extensive search, however, did not find the signature that accompanies such elements. The origin of heavy elements in the universe continues to remain as one of astronomy’s biggest open questions.

Tanmoy Laskar, coauthor on the study that published in Nature Astronomy on April 12, spoke with AtTheU about why GRB 221009A was the B.O.A.T.

We have seen gamma-ray bursts before, but this one was so bright that its light blinded our gamma-ray telescopes in space and even shook the Earth’s upper atmosphere! Several dedicated people worked very hard to reconstruct the original gamma-ray signal and found that this gamma-ray burst was by far the brightest of all time (B.O.A.T) we have ever recorded. It has been exciting to study the B.O.A.T. over the last couple of years to try to figure two big mysteries: What kind of star is responsible for this powerful light display, and what produces the heavy elements in the universe?

How can finding a supernova help in solving these mysteries?

There are two theories to what makes these powerful, gamma-ray bursts—one is the collapse of massive stars at the ends of their lives (which also results in an explosion of the star as a supernova), and the other is a merger of two neutron stars, which are dense remnants of dead stars. We looked for the signature of a supernova, which would definitively tell us which theory was responsible for the B.O.A.T. explosion.

The other reason we wanted to search for the supernova was to solve the mystery of what produces heavy metals. Supernovae are factories that manufacture many elements in the universe—could a supernova powerful enough to create the gamma-ray burst also produce heavy elements in the explosion, like platinum and gold?

Read the entire interview conducted by Lisa Potter in AtTheU.

 

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Utah Refugee Teens Build Cosmic Ray Detectors

Utah Refugee Teens Build Cosmic Ray Detectors


April 11, 2024

This collaborative cosmic ray project connects refugee youth to science

 

On April 9, 2024, a community of refugee students and their families, scientists, educators and policymakers will celebrate an event three years in the making—the installation of five cosmic ray detectors atop the Department of Workforce Services Refugee Services Office (also known as the Utah Refugee Center) in downtown Salt Lake City. The detectors, which measure echoes of cosmic particles bombarding Earth’s atmosphere, were built by nearly 60 participants in a program called “Investigating the Development of STEM-Positive Identities of Refugee Teens in a Physics Out of School Time Experience (InSPIRE)”, which brings science research—in this case particle physics—to teenagers and contributes to a worldwide effort to measure cosmic ray activity on Earth.

“Refugee youth often encounter many challenges related to STEM, including restricted exposure to STEM education, language barriers, cultural adjustments and a history of interrupted schooling, resulting in a low rate of high school completion and college matriculation among refugee students,” said Tino Nyawelo, principal investigator of InSPIRE and professor of physics and astronomy at the U. “The project conducts research to better understand these challenges and how to best broaden access to and engagement in STEM for refugee youth and other historically disenfranchised populations.”


Tino Nyawelo kicks off the cosmic ray detector installation celebration at the Utah Refugee Services Center on April 9, 2024. (Photo: Todd Anderson)

InSPIRE brings together the University of Utah, Utah State University, Utah Department of Workforce Services Refugee Services Office, as well as the Dutch National Institute for Subatomic Physics (Nikhef) in Amsterdam, to involve teens in real science. Data from the students’ cosmic rays detectors helps us understand the origins of the universe. The celebration is on Tuesday, April 9, at 1:30 p.m. at the Refugee Services Office at 150 N. 1950 W., Salt Lake City, UT 84116. A short ceremony will include speakers from the U, USU and the Refugee Services Office, and two student-participants will be available with research posters to talk about their cosmic ray detection projects.

Funded by a $1.1 million grant from the U.S. National Science Foundation in 2020, InSPIRE explores how refugee teenagers identify with STEM subjects while they participate in a cosmic ray detector-building and research project. Fifty-seven refugee teens spent one-to two-days a week for nearly three years building the detectors while learning the principles of particle physics and computer programming. The students designed their own research projects, posing questions such as whether the moon impacts cosmic rays. While some participants focused on the detectors, others focused on crafting short films on their fellow students’ research journeys. These students are working on a documentary, in partnership with the ArtsBridge America program at the U’s College of Fine Arts.

Neriman (left) and Lina Al Samaray with a poster of their research project, Effect of the Moon on Cosmic Ray Detectors. The high highschoolers used data from existing HiSPARC detectors to investigate whether the moon’s position from the horizon impacted the rate of cosmic rays hitting Earth’s surface.(Photo: Lisa Potter)

InSPIRE is embedded within Refugees Exploring the Foundations of Undergraduate Education In Science (REFUGES), an after school program that Nyawelo founded to support refugee youth in Utah’s school system, who are placed in grade levels corresponding to their ages despite going long periods without formal education. The U’s Center for Science and Mathematics Education (CSME) has housed the REFUGES program since 2012, where it has expanded to include non-refugee students who are underrepresented in STEM fields. Since then, REFUGES has worked closely with the state of Utah’s Department of Workforce Services Refugee Services Office, which serves as a critical link to the refugee community by coordinating comprehensive services to refugees resettled in our state.

“For the past 12 years, the Refugee Services Office has collaborated with the REFUGES program to identify refugee students and their families who need academic assistance and support. Participation in REFUGES keeps these students engaged in their community while also promoting their access to educational opportunities,” said Mario Kligago, director of the Utah RSO. “It’s amazing—what started as a small project funded by a Refugee Services Office grant has grown into a multi-million dollar endeavor backed by national organizations.”

The detector technology is adapted from HiSPARC (High School Project on Astrophysics Research with Cosmics), a collaboration between science institutions that started in the Netherlands, aimed at improving high schoolers’ interest in particle physics. There are now more than 140 student-built detectors on buildings in the Netherlands, Namibia, and the United Kingdom that upload their data 24/7 to publicly available databases. Nikhef in Amsterdam coordinated the project from 2003-2023 and created the initial worldwide network of cosmic ray detection data. Starting in 2024, data on extensive cosmic air showers and the digital HiSPARC infrastructure will be hosted and maintained by the U’s Center for High Performance Computing (CHPC), led by professor Nyawelo.

Read the full article in @TheU.

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Spectrum 2023

Spectrum 2023


Common Ground 2023

The official magazine of the U Department of Mining Engineering.

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Information Engines Pay the Piper

Physicists sometimes get a bad rap. Theoretical physicists even more so. Consider Sheldon Cooper in the TV sit-com The Big Bang Theory:


Sheldon
: I’m a physicist. I have a working knowledge of the entire universe and everything it contains.
Penny: Who’s Radiohead?
Sheldon: (after several seconds of twitching) I have a working knowledge of the important things in the universe.

Mikhael Semaan

But a working knowledge of anything is always informed and arguably improved — even transformed — by robust and analytical “thought experiments.” In fact, theoretical physics is key to advancing our understanding of the universe, from the cosmological to the particle scale, through mathematical models.

That is why Mikhael Semaan, Ph.D. and others like him spend their time in the abstract, standing on the figurative shoulders of past giants and figuring out what could happen . . . theoretically. That Semaan is also one of the celebrated postdoctoral researchers/mentors in the Science Research Initiative (SRI), is a coup for undergraduates at the University of Utah who “learn by doing” in a variety of labs and field sites.

“The SRI is awesome,” Semaan says. It’s “a dream job where I can continue advancing my own research while ‘bridging the gap’ in early undergraduate research experiences, giving them access to participation in the cutting edge alongside personalized mentoring.”

Want to learn how to bake something? Hire a baker. Better still, watch the baker bake (and maybe even lick the bowl when allowed). And now that Semaan’s second first-author paper — done with senior investigator Jim Crutchfield of UC Davis, his former PhD advisor — has just “dropped,” students get to witness in real time how things get done, incrementally adding to the trove of scientific knowledge that from past experience, we know, can change the world.

Theory’s abstraction lets us examine certain essential features of the subjects and models we study, which in Semaan and Crutchfield’s case concern the first and second laws of thermodynamics. Is it possible to run a car from the hard drive of a computer? In the parlance of this brand of physics, the short answer is, “Yes, theoretically.”

Thermodynamics of Information Processing

From that question as a jumping off point, Semaan explains further. “The primary impact of our contribution is, for now, mostly to other theorists working out the thermodynamics of information processing. … [W]e suggest a change in viewpoint that simplifies and unifies various preceding lines of inquiry, by combining familiar tools to uncover new results.”

The physicist and writer C.P. Snow said that the first three laws of thermodynamics can be pithily summarized with, “You can’t win. You can’t even break even. You can’t stay out of the game.” Semaan elaborates on the second law, “the universe must increase its entropy — its degree of ‘disorder’ — on average…[b]esides offering an excuse for a messy room, this statement has far-reaching implications and places strict limits on the efficiency of converting one form of energy to another … .”

These limits are obeyed by everything from the molecular motors in our bodies to the increasingly sophisticated computers in our pockets to the impacts of global industry on the Earth’s climate and beyond. Yet in the second law’s case, there’s a catch: it turns out that information in the abstract is itself a form of entropy. This insight is key to the much-celebrated “Landauer bound:” stated simply, learning about a system — going from uncertainty to certainty — fundamentally costs energy.

But what about the converse situation? If it costs energy to “reduce” uncertainty, can we extract energy by “gaining” it — for example, by scrambling a hard drive? If so, how much?

Ratchet Information

To answer this question, previous researchers, including Crutchfield, imagine a “ratchet” which moves in one direction along an “information tape,” interacting with one “bit” at a time. As it does so, the ratchet modifies the tape’s statistical properties. That “tape” could be the hard drive in your computer or could be a sequence of base pairs in a strand of DNA.

“In this situation, by scrambling an initially ordered tape, yes: we can actually extract heat from the environment, but only by increasing randomness on the tape.” While the second law still holds, it is modified. “The randomness of the information in the tape is itself a form of entropy,” explains Semaan further, “and we can reduce the entropy in our thermal environment as long as we sufficiently increase it in the tape.”

In the literature, the laws bounding this behavior are termed “information processing second laws,” in reference to their explicit accounting for information processing (via modifying the tape) in the second law of thermodynamics. In this new paper, Semaan and Crutchfield uncover an “information processing first law,” a similar modification to the first law of thermodynamics, which unifies and strengthens various second laws in the literature. It appears to do more, too: it also offers a way to tighten those second laws — to place stricter limits on the allowed behavior — for systems which have “nonequilibrium steady states.”

Non-equilibrium steady state systems — our bodies, the global climate, and our computers are all examples — need to constantly absorb and dissipate energy, and so stay out of equilibrium, even in “steady” conditions (contrast a cup of coffee left out: its “steady” state is complete equilibrium with the room).

“It turns out,” says Semaan, “that in this case we must ‘pay the piper’:  we can still scramble the tape to extract heat, but only if we do so fast enough to keep up with the non-equilibrium steady states.” To demonstrate their new bound, the authors cooked up a simple, tunable model to visualize how much tighter the new results are with concrete, if idealized, examples. “This sort of idealization is a powerful tool,” says Semaan, “because with it we can ‘zoom in’ on only those features we want to highlight and understand, in this case what having nonequilibrium steady states changes about previous results.”

This uni-directional “ratcheting” mechanism may, in fact, someday lead to engineering a device that harnesses energy from scrambling a hard drive. But first, beyond engineering difficulties, there is much left to understand about the mathematical, idealized limits of this behavior. In other words, we still have a ways to go, even “in theory.” There are plenty of remaining questions to address, the fodder for any theoretical physicist worth their salt.

Complex Systems

However, far from being “only” a theoretical exercise, says Semaan, “these continued extensions, reformulations, and corrections are necessary for us to be able to understand how real-world, highly interconnected, complex systems,” like the human body, forest ecosystems, the planetary climate, etc., “exploit (or don’t) the dynamical interplay between energy and information to function. Since so many of the intricate systems we see in nature (including ourselves) exhibit non-equilibrium steady states,” he continues, “this is a [required] step to understanding how they [do this].”

Information ratchet system: At each time step, the ratchet moves one step to the right along the tape, and interacts with one symbol at a time. As it does so, it exchanges energy in various forms with its environment — signified by the T, aux, and λ bubbles in the picture. After running for a long time, the “output tape” generated by the interactions with the ratchet has different statistical properties compared to the “input tape” it receives. The information processing first and second laws are statements about the fundamental relationship between the energy exchanged with the environment and the information processing in the tape. Credit: Semaan and Crutchfield.

This is heady stuff, and the Southern California native is positively thrilled to be sharing it with young, eager undergraduates at the U through the SRI. Semaan is keenly aware of how critical the undergraduate experience in research needs to be to turn out future physicists. A son of Lebanese immigrants who both attended college in the U.S., neither were research scientists and no one he knew had studied physics. At California State University, Long Beach, where Semaan first declared electrical engineering as his major, he was “seduced into physics” through a series of exceptional and inspirational mentors. In the SRI, he hopes to carry this experience forward, and open new doors for undergraduate students.

It was the Complexity Sciences Center at UC Davis, when he applied to graduate school, that caught his attention because of its interdisciplinary nature and concern with systems in which “the whole appears to be greater than the sum of its parts.” The study of emerging systemic behaviors, helmed by Crutchfield, the Center’s Director, ultimately inspired both his PhD and his decision to join the SRI, working with students across the entire College of Science.

Following the third law of thermodynamics, Mikhael Semaan clearly “can’t stay out of the game” (nor would he want to), but one could argue he’s more than breaking even at it.

The release of this paper, titled “First and second laws of information processing by nonequilibrium dynamical states” in the journal Physical Review E is proof of that.


by David Pace