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A photo of a 3D atomic structure information of a 2D material that was previously inaccessible due to the limitations of 2D images. A 2D image is shown beneath the 3D atomic coordinates of molybdenum in blue, sulfur in yellow and rhenium dopants in orange.

UCLA-led research team produces most accurate 3D images of ‘2D materials’

A photo of a 3D atomic structure information of a 2D material that was previously inaccessible due to the limitations of 2D images. A 2D image is shown beneath the 3D atomic coordinates of molybdenum in blue, sulfur in yellow and rhenium dopants in orange.

Image showing the 3D atomic coordinates of molybdenum (blue), sulfur (yellow) and added rhenium (orange). A 2D image is shown beneath the 3D model. (Photo Credit: Dennis Kim/UCLA)

A UCLA-led research team has produced in unprecedented detail experimental three-dimensional maps of the atoms in a so-called 2D material — matter that isn’t truly two-dimensional but is nearly flat because it’s arranged in extremely thin layers, no more than a few atoms thick.

Although 2D-materials–based technologies have not yet been widely used in commercial applications, the materials have been the subject of considerable research interest. In the future, they could be the basis for semiconductors in ever smaller electronics, quantum computer components, more-efficient batteries, or filters capable of extracting freshwater from saltwater.

The promise of 2D materials comes from certain properties that differ from how the same elements or compounds behave when they appear in greater quantities. Those unique characteristics are influenced by quantum effects — phenomena occurring at extremely small scales that are fundamentally different from the classical physics seen at larger scales. For instance, when carbon is arranged in an atomically thin layer to form 2D graphene, it is stronger than steel, conducts heat better than any other known material, and has almost zero electrical resistance.

But using 2D materials in real-world applications would require a greater understanding of their properties, and the ability to control those properties. The new study, which was published in Nature Materials, could be a step forward in that effort.

The researchers showed that their 3D maps of the material’s atomic structure are precise to the picometer scale — measured in one-trillionths of a meter. They used their measurements to quantify defects in the 2D material, which can affect their electronic properties, as well as to accurately assess those electronic properties.

“What’s unique about this research is that we determine the coordinates of individual atoms in three dimensions without using any pre-existing models,” said corresponding author Jianwei “John” Miao, a UCLA professor of physics and astronomy. “And our method can be used for all kinds of 2D materials.”

Miao is the deputy director of the STROBE National Science Foundation Science and Technology Center and a member of the California NanoSystems Institute at UCLA. His UCLA lab collaborated on the study with researchers from Harvard University, Oak Ridge National Laboratory and Rice University.

The researchers examined a single layer of molybdenum disulfide, a frequently studied 2D material. In bulk, this compound is used as a lubricant. As a 2D material, it has electronic properties that suggest it could be employed in next-generation semiconductor electronics. The samples being studied were “doped” with traces of rhenium, a metal that adds spare electrons when replacing molybdenum. That kind of doping is often used to produce components for computers and electronics because it helps facilitate the flow of electrons in semiconductor devices.

To analyze the 2D material, the researchers used a new technology they developed based on scanning transmission electron microscopy, which produces images by measuring scattered electrons beamed through thin samples. Miao’s team devised a technique called scanning atomic electron tomography, which produces 3D images by capturing a sample at multiple angles as it rotates.

The scientists had to avoid one major challenge to produce the images: 2D materials can be damaged by too much exposure to electrons. So for each sample, the researchers reconstructed images section by section and then stitched them together to form a single 3D image — allowing them to use fewer scans and thus a lower dose of electrons than if they had imaged the entire sample at once.

The two samples each measured 6 nanometers by 6 nanometers, and each of the smaller sections measured about 1 nanometer by 1 nanometer. (A nanometer is one-billionth of a meter.)

The resulting images enabled the researchers to inspect the samples’ 3D structure to a precision of 4 picometers in the case of molybdenum atoms — 26 times smaller than the diameter of a hydrogen atom. That level of precision enabled them to measure ripples, strain distorting the shape of the material, and variations in the size of chemical bonds, all changes caused by the added rhenium — marking the most accurate measurement ever of those characteristics in a 2D material.

“If we just assume that introducing the dopant is a simple substitution, we wouldn’t expect large strains,” said Xuezeng Tian, the paper’s co-first author and a UCLA postdoctoral scholar. “But what we have observed is more complicated than previous experiments have shown.”

The scientists found that the largest changes occurred in the smallest dimension of the 2D material, its three-atom-tall height. It took as little as a single rhenium atom to introduce such local distortion.

► Read a Nature analysis of the UCLA-led study

Armed with information about the material’s 3D coordinates, scientists at Harvard led by Professor Prineha Narang performed quantum mechanical calculations of the material’s electronic properties.

“These atomic-scale experiments have given us a new lens into how 2D materials behave and how they should be treated in calculations, and they could be a game changer for new quantum technologies,” Narang said.

Without access to the sort of measurements generated in the study, such quantum mechanical calculations conventionally have been based on a theoretical model system that is expected at a temperature of absolute zero.

The study indicated that the measured 3D coordinates led to more accurate calculations of the 2D material’s electronic properties.

“Our work could transform quantum mechanical calculations by using experimental 3D atomic coordinates as direct input,” said UCLA postdoctoral scholar Dennis Kim, a co-first author of the study. “This approach should enable material engineers to better predict and discover new physical, chemical and electronic properties of 2D materials at the single-atom level.”

Other authors were Yongsoo Yang, Yao Yang and Yakun Yuan of UCLA; Shize Yang and Juan-Carlos Idrobo of Oak Ridge National Laboratory; Christopher Ciccarino and Blake Duschatko of Harvard; and Yongji Gong and Pulickel Ajayan of Rice.

The research was supported by the U.S. Department of Energy, the U.S. Army Research Office, and STROBE National Science Foundation Science and Technology Center. The scanning transmission electron microscopy experiments were conducted at the Center for Nanophase Materials Sciences, a DOE user facility at Oak Ridge National Laboratory.

This article originally appeared in the UCLA Newsroom.

A photo of the Owens Valley lakebed.

Effort to limit dust pollution in Owens Valley is advancing, but still room to improve

A photo of the Owens Valley lakebed.

The Owens Valley lakebed with currently approved dust mitigation measures. (Photo Credit: David Colgan/UCLA)

The century-long battle over water between California’s Owens Valley and Los Angeles is nothing short of epic.

In 1974, the conflict was immortalized in the film “Chinatown.” The latest chapter comes in a more stoic but important form: a 157-page report from the National Academies of Sciences, Engineering and Medicine. The publication was created by a panel of experts that includes UCLA atmospheric dust specialist Gregory Okin.

Beginning in the late 1800s, William Mulholland quietly bought up land and water rights in Owens Valley, and in 1913, he started delivering the water from Owens Lake 233 miles south via aqueduct to a fast-growing Los Angeles.

The population of Los Angeles was 102,000 in 1910, but it had reached 319,000 in 1920 and then soared to 2 million by the middle of the century. Owens Valley, its lake drained of water, had become the largest source of dust in North America.

That dust included particulate matter measuring 10 micrometers or less in diameter, pollution that gets deep into people’s lungs and causes respiratory problems, particularly for sensitive groups. Ranchers, indigenous people and other residents of the valley were incensed, having lost their water and gained unhealthy air in its place.

The National Academies’ peer-reviewed report comes following decades of litigation that required the Los Angeles Department of Water and Power to take actions to mitigate the dust problem. Over the past two decades, the department has spent $2 billion on the effort.

And researchers found good news: Efforts between the department and Great Basin Unified Air Pollution Control District to control the issue have gone well. The work includes using gravel, managed vegetation and shallow flooding to mitigate dust. The air pollution district is a government agency responsible for protecting air quality in the east-central part of the state, near the Nevada border. It battled the Department of Water and Power in court for decades, but outside the courtroom the relationship is less contentious.

“The teams of people working on the ground together have been very successful,” said Okin, who is also a member of the UCLA Institute of the Environment and Sustainability. “There are still air quality exceedances that occur, but they are drastically smaller in magnitude and frequency than they were prior to 2000.”

That doesn’t mean there isn’t room for improvement. The report also recommended that processes for minimizing dust established 20 years ago should be updated with new technology and processes that would also help save water and power and preserve cultural and aesthetic values.

“Despite the fact that they’ve done a great job, they’ve done it in an ad hoc manner,” Okin said, referring to the two agencies. “There’s not a lot of logic as to what is being done and where.”

A photo of a crowd of 30,000 people who watched the first water cascade through the aqueduct in the San Fernando Valley.

A crowd of 30,000 watched the first water cascade through the aqueduct in the San Fernando Valley. (Photo Credit: Courtesy of waterandpower.org)

The methods workers can use to mitigate dust are strictly controlled by a series of legal agreements. And testing new methods poses a challenge, because testing is prohibited in the areas of the valley in which dust pollution has been substantially controlled.

“The only place you can test new measures is in areas that don’t need to be controlled, which is crazy,” Okin said.

The report suggests that the air pollution control district and the Department of Water and Power work together to redesign the entire system of dust control in the lakebed.

“The current work is probably using more water, power and heavy machinery than it needs to,” Okin said.

Better managing the area could also be a boon for wildlife. Currently, one of the main approaches to mitigating dust in the area is to plant grass, which requires a lot of irrigation. Okin suggested other native species could replace grass in some areas, which would save water and create new living spaces for birds, rare aquatic life and other species wildlife.

The report also notes that planning for future efforts must account for also climate change, which is projected to increase temperatures and make precipitation patterns and dry spells more extreme. The 2017 rainy season, for example, flooded the valley with more water than the Los Angeles Aqueduct could take, causing water levels in the mostly-dry lake to rise substantially.

The competing interests of the two main players could make it difficult to improve the situation further, Okin said. While the air pollution control district is primarily interested in dust mitigation, the Department of Water and Power cares mostly about conserving water as a resource. Bringing new efficiency and sustainability to the process would likely require further involvement of third parties such as the academies that created the report.

It’s been more than a century since Mulholland said, “There it is, take it,” as the first Owens Valley water flowed through the aqueduct into Los Angeles. Now, the question is how the next century of this drama, which affects the lives of millions, will unfold.

This article originally appeared in the UCLA Newsroom.

A photo collage: from left, top row: Elaine Hsiao, Andrea Ghez, Sarah Stein. From left, bottom row: Heather Adams and Lynn Vavreck.

UCLA College Celebrates International Women’s Day

A photo collage: from left, top row: Elaine Hsiao, Andrea Ghez, Sarah Stein. From left, bottom row: Heather Adams and Lynn Vavreck.

From left, top row: Elaine Hsiao, Andrea Ghez, Sarah Stein. From left, bottom row: Heather Adams and Lynn Vavreck.

On International Women’s Day we give a shout-out to five incredible UCLA College faculty whose research and accomplishments are truly awe-inspiring—including discoveries about our galaxy’s black hole, landing on The Economist’s “Best of 2019” book list, spearheading one of the largest public opinion surveys for the 2020 election, revealing how anti-depressants affect our gut microbiome, and advocating for transfer students. See our highlights below.

Physical Sciences

A photo of Andrea Ghez.

Andrea Ghez (Photo Credit: Christopher Dibble)

Astronomers discover class of strange objects near our galaxy’s enormous black hole

Astronomers from UCLA’s Galactic Center Orbits Initiative have discovered new objects that “look like gas and behave like stars,” said co-author Andrea Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and director of the UCLA Galactic Center Group.

 

Social Sciences

A photo of Lynn Vavreck.

Lynn Vavreck (Photo Credit: UCLA)

UCLA political scientists launch one of largest-ever public opinion surveys for run-up to 2020

UCLA political scientists Lynn Vavreck and Chris Tausanovitch launch one of largest-ever public opinion surveys for the run-up to 2020 elections.

 

Life Sciences

A photo of Elaine Hsiao.

Elaine Hsiao (Photo Credit: Reed Hutchinson/UCLA)

Study shows how serotonin and a popular anti-depressant affect the gut’s microbiota

Senior author Elaine Hsiao, along with a team of researchers, hopes to build on their current study to learn whether microbial interactions with antidepressants have consequences for health and disease.

 

Humanities

A photo of Sarah Abrevaya Stein.

Sarah Abrevaya Stein (Photo Credit: Caroline Libresco)

Professor’s book about Sephardic Jews chosen as a Best of 2019

The Economist has named to its Best of 2019 list, “Family Papers: A Sephardic Journey Through the Twentieth Century,” by Sarah Abrevaya Stein, Sady and Ludwig Kahn Director, Alan D. Leve Center for Jewish Studies.

 

Undergraduate Education

A photo of Heather Adams, first row center, former director of the UCLA Transfer Student Center.

Heather Adams, first row center. (Photo Credit: Ivan Mendez/UCLA)

UCLA’s Heather Adams wins national award for work helping transfer students

Adams was honored by the National Institute for the Study of Transfer Students.

 

 

An illustration that shows the Earth’s magnetosphere during a magnetic storm.

Researchers discover a new source of space weather – too close to home

An illustration that shows the Earth’s magnetosphere during a magnetic storm.

An illustration shows the Earth’s magnetosphere during a magnetic storm. At right, three satellites witnessed reconnection close to geosynchronous orbit where many other critical satellites reside. The red “X” identifies the reconnection site, and the yellow arrows indicate the direction of explosive outflows of energized particles toward and away from Earth. Earth-directed electrons (shown in red and pink) carry energy along magnetic field lines to power the aurora at Earth’s north and south poles. These energized electrons were detected by a weather satellite (center).

Beyond Earth’s atmosphere are swirling clouds of energized particles — ions and electrons — that emanate from the sun. This “solar wind” buffets the magnetosphere, the magnetic force field that surrounds Earth.

In much the same way winds and storms create weather in our atmosphere, strong gusts of solar wind penetrating the magnetosphere can generate magnetic storms with powerful electric currents that can impact our lives.

A new study by the NASA THEMIS mission team — led by Vassilis Angelopoulos, a UCLA professor of space physics — is the first to show that such storms can originate much closer to Earth than previously thought, overlapping with the orbits of critical weather, communications and GPS satellites. The team’s findings are published in the journal Nature Physics.

Magnetic storms can produce dazzling northern lights or hazardous particles careening toward spacecraft and astronauts, zapping them out of commission. Under certain conditions, magnetic storms can disable the electrical grid, disrupt radio communications and corrode pipelines, even creating extreme aurora visible close to the equator.

“By studying the magnetosphere, we improve our chances of dealing with the greatest hazard to humanity venturing into space: storms powered by the sun,” Angelopoulos said.

An incident that illustrates the dramatic power of magnetic storms occurred in 1921, when such a storm disrupted telegraph communications and caused power outages that resulted in a New York City train station burning to the ground. And in 1972 the Apollo 16 and 17 astronauts narrowly missed what could have been a lethal solar eruption. These incidents underscore the potential dangers that should be assessed as more humans venture into orbit. If a similar storm occurred today, a separate study estimated, economic losses in the U.S. due to electrical blackouts only could surpass $40 billion a day.

How electric currents in space influence the aurora and magnetic storms has been long debated in the space physics community. Because the storms occur so rarely and satellite coverage is sparse, it has been difficult for researchers to detect the dynamic process that powers those storms.

When solar wind magnetic energy is transferred into the magnetosphere, it builds up until it is converted into heat and particle acceleration through a process called magnetic reconnection. After decades of study, it is still unclear to researchers where exactly magnetic reconnection occurs during storms.

Recent observations by multiple satellites have shown that magnetic storms can be initiated by magnetic reconnection much closer to Earth than previously thought possible. The three NASA THEMIS satellites observed magnetic reconnection only about three to four Earth diameters away. The researchers did not expect this could happen in the comparatively stable magnetic field configuration near Earth.

Later, a weather satellite, which was nearer to Earth in geostationary orbit, detected energized particles associated with magnetic storms.

The weather satellite proved that this near-Earth reconnection stimulated ion and electron acceleration to high energies, posing a hazard to hundreds of satellites operating in this common orbit. Such particles can damage electronics and human DNA, increasing the risk of radiation poisoning and cancer for astronauts. Some particles can even enter the atmosphere and affect airline passengers.

“Only with such direct measurements of magnetic reconnection and its resulting energy flows could we convincingly prove such an unexpected mechanism of storm power generation,” said Angelopoulos, who is lead author of the paper. “Capturing this rare event, nearer to Earth than ever detected before, forces us to revise prior assumptions about the reconnection process.”

This discovery will ultimately help scientists refine predictive models of how the magnetosphere responds to solar wind, providing precious extra hours or even days to prepare satellites, astronauts and the energy grid for the next “big one” in space.

This article originally appeared in the UCLA Newsroom.

Photos of UCLA College professors Jose Rodriguez and Erik Petigura.

Two UCLA College faculty members awarded 2020 Sloan Research Fellowships

Photos of UCLA College professors Jose Rodriguez and Erik Petigura.

UCLA College professors Jose Rodriguez (left) and Erik Petigura (right).

Two young UCLA College professors, and two others, are among 126 scientists and scholars from more than 60 colleges and universities in the United States and Canada selected today to receive 2020 Sloan Research Fellowships. UCLA is tied for fifth — behind only Stanford, UC Berkeley, UC San Diego and the Massachusetts Institute of Technology — in the number of faculty honored this year by the Alfred P. Sloan Foundation, which selects early-career scientists and scholars who are rising stars of science.

“To receive a Sloan Research Fellowship is to be told by your fellow scientists that you stand out among your peers,” says Adam F. Falk, president of the Alfred P. Sloan Foundation. “A Sloan Research Fellow is someone whose drive, creativity and insight make them a researcher to watch.”

Since the first Sloan Research Fellowships were awarded in 1955, 165 UCLA faculty members have received Sloan Research Fellowships. UCLA College’s 2020 recipients are:

Erik Petigura

Petigura, an assistant professor of physics and astronomy in the UCLA College, studies exoplanets — planets orbiting stars other than the sun — using ground-based and space-based telescopes. “My passion for exoplanets is motivated by a deceptively simple, yet fundamental question: Why are we here?” said Petigura. “Our species has wrestled with this question since antiquity, and it resonates strongly with me.” Exoplanets offer the key avenue toward answering this question, as they inform the otherwise elusive physical processes that led to the formation of the solar system, the formation of the Earth and the origin of life. His group has shown that nearly every sun-like star has a planet between the size of Earth and Neptune — sizes not present in the solar system. “In other words, our solar system is not a typical outcome of planet formation, at least in that one key respect,” he said. As a Sloan Fellow, Petigura plans to study the origin, evolution and fate of these ubiquitous planets.

Jose Rodriguez

Rodriguez, an assistant professor of chemistry and biochemistry in the UCLA College, develops and applies new scientific methods in bio-imaging to determine, and provide a deep scientific understanding of, cellular and molecular structures and reveal undiscovered structures that influence chemistry, biology and medicine. His research combines computational, biochemical and biophysical experiments. His laboratory is working to explore the structures adopted by prions — a form of infectious protein that causes neurodegenerative disorders. Prion proteins, like the amyloid proteins associated with Alzheimer’s disease, form large clumps that damage and ultimately kill neurons in the brain. Among his awards and honors, Rodriguez won a 2019 Packard fellowship for Science and Engineering by the David and Lucile Packard Foundation; a 2018 Pew scholar in the biomedical sciences, a 2017 Searle Scholar and a 2017 Beckman Young Investigator by the Arnold and Mabel Beckman Foundation.

Winners of Sloan Research Fellowships receive a two-year, $75,000 award to support their research. The fellowships are intended to enhance the careers of exceptional young scientists and scholars in chemistry, computer science, economics, mathematics, computational and evolutionary molecular biology, neuroscience, ocean sciences and physics. The Sloan Foundation, which is based in New York, was established in 1934.

This article originally appeared in the UCLA Newsroom.

Photo of orbits of the G objects at the center of our galaxy

Astronomers discover class of strange objects near our galaxy’s enormous black hole

Photo of orbits of the G objects at the center of our galaxy

Orbits of the G objects at the center of our galaxy, with the supermassive black hole indicated with a white cross. Stars, gas and dust are in the background. Photo: Anna Ciurlo, Tuan Do/UCLA Galactic Center Group

Astronomers from UCLA’s Galactic Center Orbits Initiative have discovered a new class of bizarre objects at the center of our galaxy, not far from the supermassive black hole called Sagittarius A*. They published their research in the Jan. 16 issue of the journal Nature.

“These objects look like gas and behave like stars,” said co-author Andrea Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and director of the UCLA Galactic Center Group.

The new objects look compact most of the time and stretch out when their orbits bring them closest to the black hole. Their orbits range from about 100 to 1,000 years, said lead author Anna Ciurlo, a UCLA postdoctoral researcher.

Ghez’s research group identified an unusual object at the center of our galaxy in 2005, which was later named G1. In 2012, astronomers in Germany made a puzzling discovery of a bizarre object named G2 in the center of the Milky Way that made a close approach to the supermassive black hole in 2014. Ghez and her research team believe that G2 is most likely two stars that had been orbiting the black hole in tandem and merged into an extremely large star, cloaked in unusually thick gas and dust.

“At the time of closest approach, G2 had a really strange signature,” Ghez said. “We had seen it before, but it didn’t look too peculiar until it got close to the black hole and became elongated, and much of its gas was torn apart. It went from being a pretty innocuous object when it was far from the black hole to one that was really stretched out and distorted at its closest approach and lost its outer shell, and now it’s getting more compact again.”

“One of the things that has gotten everyone excited about the G objects is that the stuff that gets pulled off of them by tidal forces as they sweep by the central black hole must inevitably fall into the black hole,” said co-author Mark Morris, UCLA professor of physics and astronomy. “When that happens, it might be able to produce an impressive fireworks show since the material eaten by the black hole will heat up and emit copious radiation before it disappears across the event horizon.”

But are G2 and G1 outliers, or are they part of a larger class of objects? In answer to that question, Ghez’s research group reports the existence of four more objects they are calling G3, G4, G5 and G6. The researchers have determined each of their orbits. While G1 and G2 have similar orbits, the four new objects have very different orbits.

Ghez believes all six objects were binary stars — a system of two stars orbiting each other — that merged because of the strong gravitational force of the supermassive black hole. The merging of two stars takes more than 1 million years to complete, Ghez said.

“Mergers of stars may be happening in the universe more often than we thought, and likely are quite common,” Ghez said. “Black holes may be driving binary stars to merge. It’s possible that many of the stars we’ve been watching and not understanding may be the end product of mergers that are calm now. We are learning how galaxies and black holes evolve. The way binary stars interact with each other and with the black hole is very different from how single stars interact with other single stars and with the black hole.”

Ciurlo noted that while the gas from G2’s outer shell got stretched dramatically, its dust inside the gas did not get stretched much. “Something must have kept it compact and enabled it to survive its encounter with the black hole,” Ciurlo said. “This is evidence for a stellar object inside G2.”

“The unique dataset that Professor Ghez’s group has gathered during more than 20 years is what allowed us to make this discovery,” Ciurlo said. “We now have a population of ‘G’ objects, so it is not a matter of explaining a ‘one-time event’ like G2.”

The researchers made observations from the W.M. Keck Observatory in Hawaii and used a powerful technology that Ghez helped pioneer, called adaptive optics, which corrects the distorting effects of the Earth’s atmosphere in real time. They conducted a new analysis of 13 years of their UCLA Galactic Center Orbits Initiative data.

In September 2019, Ghez’s team reported that the black hole is getting hungrier and it is unclear why. The stretching of G2 in 2014 appeared to pull off gas that may recently have been swallowed by the black hole, said co-author Tuan Do, a UCLA research scientist and deputy director of the Galactic Center Group. The mergers of stars could feed the black hole.

The team has already identified a few other candidates that may be part of this new class of objects, and are continuing to analyze them.

Ghez noted the center of the Milky Way galaxy is an extreme environment, unlike our less hectic corner of the universe.

“The Earth is in the suburbs compared to the center of the galaxy, which is some 26,000 light-years away,” Ghez said. “The center of our galaxy has a density of stars 1 billion times higher than our part of the galaxy. The gravitational pull is so much stronger. The magnetic fields are more extreme. The center of the galaxy is where extreme astrophysics occurs — the X-sports of astrophysics.”

Ghez said this research will help to teach us what is happening in the majority of galaxies.

Other co-authors include Randall Campbell, an astronomer with the W.M. Keck Observatory in Hawaii; Aurelien Hees, a former UCLA postdoctoral scholar, now a researcher at the Paris Observatory in France; and Smadar Naoz, a UCLA assistant professor of physics and astronomy.

The research is funded by the National Science Foundation, W.M. Keck Foundation and Keck Visiting Scholars Program, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, Jim and Lori Keir, and Howard and Astrid Preston.

In July 2019, Ghez’s research team reported on the most comprehensive test of Einstein’s iconic general theory of relativity near the black hole. They concluded that Einstein’s theory passed the test and is correct, at least for now.

► Watch a four-minute film about Ghez’s research

►View an animation below of the orbits of the G objects, together with the orbits of stars near the supermassive black hole. Credit: Advanced Visualization Lab, National Center for Supercomputing Applications, University of Illinois

This article originally appeared in the UCLA Newsroom.

That Supermassive Black Hole in our Galaxy? It has a Friend.

Two black holes are entwined in a gravitational tango in this artist’s conception. Photo Credit: NASA/JPL-Caltech/SwRI/MSSS/Christopher Go

Smadar Naoz is an associate professor of physics and astronomy in the UCLA College. She wrote this article for The Conversation.

Do supermassive black holes have friends? The nature of galaxy formation suggests that the answer is yes, and in fact, pairs of supermassive black holes should be common in the universe.

I am an astrophysicist and am interested in a wide range of theoretical problems in astrophysics, from the formation of the very first galaxies to the gravitational interactions of black holes, stars and even planets. Black holes are intriguing systems, and supermassive black holes and the dense stellar environments that surround them represent one of the most extreme places in our universe.

The supermassive black hole that lurks at the center of our galaxy, called Sgr A*, has a mass of about 4 million times that of our sun. A black hole is a place in space where gravity is so strong that neither particles or light can escape from it. Surrounding Sgr A* is a dense cluster of stars. Precise measurements of the orbits of these stars allowed astronomers to confirm the existence of this supermassive black hole and to measure its mass. For more than 20 years, scientists have been monitoring the orbits of these stars around the supermassive black hole. Based on what we’ve seen, my colleagues and I show that if there is a friend there, it might be a second black hole nearby that is at least 100,000 times the mass of the sun.

Supermassive black holes and their friends

Almost every galaxy, including our Milky Way, has a supermassive black hole at its heart, with masses of millions to billions of times the mass of the sun. Astronomers are still studying why the heart of galaxies often hosts a supermassive black hole. One popular idea connects to the possibility that supermassive holes have friends.

To understand this idea, we need to go back to when the universe was about 100 million years old, to the era of the very first galaxies. They were much smaller than today’s galaxies, about 10,000 or more times less massive than the Milky Way. Within these early galaxies the very first stars that died created black holes, of about tens to thousand the mass of the sun. These black holes sank to the center of gravity, the heart of their host galaxy. Since galaxies evolve by merging and colliding with one another, collisions between galaxies will result in supermassive black hole pairs – the key part of this story. The black holes then collide and grow in size as well. A black hole that is more than a million times the mass of our sun is considered supermassive.

If indeed the supermassive black hole has a friend revolving around it in close orbit, the center of the galaxy is locked in a complex dance. The partners’ gravitational tugs will also exert its own pull on the nearby stars disturbing their orbits. The two supermassive black holes are orbiting each other, and at the same time, each is exerting its own pull on the stars around it.

The gravitational forces from the black holes pull on these stars and make them change their orbit; in other words, after one revolution around the supermassive black hole pair, a star will not go exactly back to the point at which it began.

Using our understanding of the gravitational interaction between the possible supermassive black hole pair and the surrounding stars, astronomers can predict what will happen to stars. Astrophysicists like my colleagues and me can compare our predictions to observations, and then can determine the possible orbits of stars and figure out whether the supermassive black hole has a companion that is exerting gravitational influence.

Using a well-studied star, called S0-2, which orbits the supermassive black hole that lies at the center of the galaxy every 16 years, we can already rule out the idea that there is a second supermassive black hole with mass above 100,000 times the mass of the sun and farther than about 200 times the distance between the sun and the Earth. If there was such a companion, then I and my colleagues would have detected its effects on the orbit of SO-2.

But that doesn’t mean that a smaller companion black hole cannot still hide there. Such an object may not alter the orbit of SO-2 in a way we can easily measure.

The physics of supermassive black holes

Supermassive black holes have gotten a lot of attention lately. In particular, the recent image of such a giant at the center of the galaxy M87 opened a new window to understanding the physics behind black holes.

The proximity of the Milky Way’s galactic center – a mere 24,000 light-years away – provides a unique laboratory for addressing issues in the fundamental physics of supermassive black holes. For example, astrophysicists like myself would like to understand their impact on the central regions of galaxies and their role in galaxy formation and evolution. The detection of a pair of supermassive black holes in the galactic center would indicate that the Milky Way merged with another, possibly small, galaxy at some time in the past.

That’s not all that monitoring the surrounding stars can tell us. Measurements of the star S0-2 allowed scientists to carry out a unique test of Einstein’s general theory of relativity. In May 2018, S0-2 zoomed past the supermassive black hole at a distance of only about 130 times the Earth’s distance from the sun. According to Einstein’s theory, the wavelength of light emitted by the star should stretch as it climbs from the deep gravitational well of the supermassive black hole.

The stretching wavelength that Einstein predicted – which makes the star appear redder – was detected and proves that the theory of general relativity accurately describes the physics in this extreme gravitational zone. I am eagerly awaiting the second closest approach of S0-2, which will occur in about 16 years, because astrophysicists like myself will be able to test more of Einstein’s predictions about general relativity, including the change of the orientation of the stars’ elongated orbit. But if the supermassive black hole has a partner, this could alter the expected result.

Finally, if there are two massive black holes orbiting each other at the galactic center, as my team suggests is possible, they will emit gravitational waves. Since 2015, the LIGO-Virgo observatories have been detecting gravitational wave radiation from merging stellar-mass black holes and neutron stars. These groundbreaking detections have opened a new way for scientists to sense the universe.

Any waves emitted by our hypothetical black hole pair will be at low frequencies, too low for the LIGO-Virgo detectors to sense. But a planned space-based detector known as LISA may be able to detect these waves which will help astrophysicists figure out whether our galactic center black hole is alone or has a partner.

This article originally appeared in the UCLA Newsroom.

Image of interstellar comet.

New NASA image provides more details about first observed interstellar comet

Image of interstellar comet.

The interstellar comet Comet 2I/Borisov (blueish image at right) near a spiral galaxy (left), in an image taken Nov. 16. Photo credit: NASA, ESA and David Jewitt/UCLA

A new image from NASA’s Hubble Space Telescope provides important new details about the first interstellar comet astronomers have seen in our solar system.

The comet, called Comet 2I/Borisov (the “I” stands for interstellar), was spotted near a spiral galaxy known as 2MASX J10500165-0152029. It was approximately 203 million miles from Earth when the image was taken on Nov. 16.

“Data from the Hubble Space Telescope give us the best measure of the size of comet 2I/Borisov’s nucleus, which is the really important part of the comet,” said David Jewitt, a UCLA professor of planetary science and astronomy who analyzed and interpreted the data from the new image.

Jewitt collaborated on the new analysis with colleagues from the University of Hawaii, Germany’s Max Planck Institute for Solar System Research, the Space Telescope Science Institute in Baltimore and Johns Hopkins University’s Applied Physics Laboratory. The scientists were surprised to learn that the nucleus has a radius measuring only about half of a kilometer — or less than one-fifteenth the size that earlier investigations suggested it might be.

“That is important because knowing its size helps us to determine the total number, and mass, of other similar objects in the solar system and the Milky Way,” Jewitt said. “2I/Borisov is the first known interstellar comet, and we would like to learn how many others there are.”

The comet is traveling at a breathtaking speed of 110,000 miles per hour — one of the fastest comets ever seen, Jewitt said. More commonly, comets travel at about half that speed.

Crimean astronomer Gennady Borisov discovered the comet on Aug. 30, using a telescope he built. Based on precise measurements of its changing position, the International Astronomical Union’s Minor Planet Center calculated a likely orbit for the comet, which shows that it came from elsewhere in the galaxy. Jewitt said its precise point of origin is unknown.

A second Hubble Space Telescope image of the comet, taken on Dec. 9, shows the comet even closer to Earth, approximately 185 million miles from Earth, he said.

Comets are icy bodies thought to be fragments left behind when planets form in the outer parts of planetary systems.

Observations by numerous telescopes show that the comet’s chemical composition is similar to that of comets previously observed in our solar system, which provides evidence that comets also form around other stars, Jewitt said. By mid-2020, the comet will have zoomed past Jupiter on its way back into interstellar space, where it will drift for billions of years, Jewitt said.

This article originally appeared in the UCLA Newsroom.

Picture of Hindou Oumarou Ibrahim.

Activist Hindou Oumarou Ibrahim wins Pritzker Award for young environmental innovators

Picture of Hindou Oumarou Ibrahim.

Hindou Oumarou Ibrahim reacts to the award announcement as UCLA professor Magali Delmas (left) looks on. Photo: Jonathan Young/UCLA

The UCLA Institute of the Environment and Sustainability presented the 2019 Pritzker Emerging Environmental Genius Award to Hindou Oumarou Ibrahim, a member of Chad’s Mbororo indigenous semi-nomadic community.

Ibrahim promotes environmental protections for indigenous groups through work with international organizations, including as a member of the United Nations Indigenous Peoples Partnership’s policy board. She also leads a community-based environmental coalition in the region surrounding Lake Chad, a critical water source that has shrunk 90% since 1980 — in part because temperatures in the area rose 1.5 degrees Celsius over the past century. Violent conflict has occasionally broken out among groups competing for the vital resource.

The annual award carries a prize of $100,000, which is funded through a portion of a $20 million gift to UCLA from the Anthony and Jeanne Pritzker Family Foundation. It is the field’s first major honor specifically for innovators under the age of 40 — those whose work stands to benefit most from the prize money and the prestige it conveys.

Ibrahim said the award, which was presented Nov. 7 at UCLA’s Hershey Hall, will help amplify the voices of 370 million indigenous people around the world.

“The voices of indigenous people are being heard here — through me, through all of you and through this prize,” Ibrahim said. “We are all together. We will win this battle, I am so confident.”

University researchers, Pentagon experts and others have found that rapid climate change — driven largely by human-caused carbon emissions — have contributed to a growing number of armed conflicts. The phenomenon is expected to particularly affect regions that are already unstable.

To prevent and reduce conflict in the Lake Chad basin, Ibrahim developed a program that gathers information on natural resources from farmers, fisherman and herders in more than a dozen African ethnic groups, and then produces 3D maps of those natural resources that their communities can share. The effort is intended to reduce the chance for conflict among the groups.

“It’s amazing to see women and men who have never been to school working jointly to build 3D maps that share critical knowledge, like where fresh water can be found even in the worst days of a drought,” Ibrahim wrote in her award application. “But the most interesting aspect of this project is that it helps to reduce conflict and tension between communities.”

Hindou is an official adviser to the UN Secretary General in advance of a major climate summit taking place in Glasgow in September 2020. She also advocates for indigenous peoples’ rights, women’s rights and environmental justice in high-profile global forums, including as a National Geographic Explorer and a senior indigenous fellow for Conservation International.

Picture of a group taking a selfie.

Shawn Escoffery, executive director of the Roy and Patricia Disney Foundation, with the 2019 Pritzker Award finalists, May Boeve, Hindou Oumarou Ibrahim and Varshini Prakash. Photo: Jonathan Young/UCLA

The Pritzker Award is open to anyone working to solve environmental challenges through any lens — from science to advocacy and entrepreneurism. But all three finalists for this year’s award were activists, which may reflect the global trend of young people taking a more vigorous role in fighting against climate change. In addition to Ibrahim, the finalists were May Boeve, executive director of 350.org, and Varshini Prakash, founder of the Sunrise Movement. Finalists were selected by a panel of UCLA faculty from 20 candidates who were nominated by an international group of environmental leaders.

Ibrahim was chosen as winner by five distinguished judges: Shawn Escoffery, executive director of the Roy and Patricia Disney Foundation; sustainability and marketing expert Geof Rochester; philanthropists Wendy Schmidt and Nicolas Berggruen; and Kathryn Sullivan, former head of the National Oceanic and Atmospheric Administration and the first American woman to walk in space.

Peter Kareiva, director of UCLA Institute of the Environment and Sustainability, said the Pritzker Award’s biggest value is that it brings together a community of candidates, past winners, UCLA faculty and the environmental leaders who serve as judges and nominators.

“We’re way beyond the time where a single innovation is going to do it, a single policy is going to do it. We’re way beyond that,” Kareiva said.

After receiving the award from Tony Pritzker, Ibrahim echoed that sentiment and called the other finalists up to the podium.

“We need action, and this action can only happen if we all join hands,” Ibrahim said. “We will make it all together.”

This article originally appeared in the UCLA Newsroom.

UCLA astronomer gets best look at first comet from outside our solar system

The comet 2I/Borisov, as seen on Oct. 12 with NASA’s Hubble Space Telescope. Scientists believe the comet is from another solar system. Photo credit: NASA, ESA and David Jewitt/UCLA

David Jewitt, a UCLA professor of planetary science and astronomy, has captured the best and sharpest look at a comet from outside of our solar system that recently barged into our own. It is the first interstellar comet astronomers have observed.

Comet 2I/Borisov (the “I” stands for interstellar) is following a path around the sun at a blazing speed of approximately 110,000 miles per hour, or about as fast as Earth travels around the sun. Jewitt studied it on Oct. 12 using NASA’s Hubble Space Telescope, which captured images of the object when it was about 260 million miles away. He observed a central concentration of dust around the comet’s solid icy nucleus — the nucleus itself is too small to be seen by Hubble — with a 100,000-mile-long dust tail streaming behind.

Jewitt said it’s very different from another interstellar object, dubbed ‘Oumuamua, that a University of Hawaii astronomer observed in 2017 before it raced out of our solar system.

“‘Oumuamua looked like a bare rock, but Borisov is really active — more like a normal comet,” said Jewitt, who leads the Hubble team. “It’s a puzzle why these two are so different. There is so much dust on this thing we’ll have to work hard to dig out the nucleus.”

That work will involve sophisticated image processing to separate the light scattered from the nucleus from light scattered by dust.

► View a 2-second time lapse video of the comet

2I/Borisov and ‘Oumuamua are the first two objects that have traveled from outside of our solar system into ours that astronomers have observed, but that’s because scientists’ knowledge and equipment are much better now than they ever have been, and because they know how to find them. One study indicates there are thousands of such comets in our solar system at any given time, although most are too faint to be detected with current telescopes.

Until 2I/Borisov, every comet that astronomers have observed originated from one of two places. One is the Kuiper belt, a region at the periphery of our solar system, beyond Neptune, that Jewitt co-discovered in 1992. The other is the Oort Cloud, a very large spherical region approximately a light-year from the sun, which astronomers think contains hundreds of billions of comets.

2I/Borisov was initially detected on Aug. 30 by Gennady Borisov at the Crimean Astrophysical Observatory, when it was 300 million miles from the sun. Jewitt said its unusually fast speed — too fast for the sun’s gravity to keep it bound in an orbit — indicates that it came from another solar system and that it is on a long path en route back to its home solar system.

Because the comet was presumably forged in a distant solar system, the comet provides valuable clues about the chemical composition and structure of the system where it originated.

2I/Borisov will be visible in the southern sky for several months. It will make its closest approach to the sun on Dec. 7, when it will be twice as far from the sun as Earth is. By the middle of 2020, it will pass Jupiter on its way back into interstellar space, where it will drift for billions of years, Jewitt said.

Comets are icy bodies thought to be fragments left behind when planets form in the outer parts of planetary systems.

20 new moons for Saturn

In separate research that has not yet been published, Jewitt is part of a team that has identified 20 previously undiscovered moons of Saturn, for a new total of 82 moons. The revised figure gives Saturn more moons than Jupiter, which has 79.

The new objects are all small, typically a few miles in diameter, and were discovered using the Subaru telescope on Maunakea in Hawaii. They can be seen only using the world’s largest telescopes, Jewitt said.

The moons might have formed in the Kuiper belt, said Jewitt, a member of the National Academy of Sciences and a fellow of the American Association for the Advancement of Science and of the American Academy of Arts and Sciences.

The research team was headed by Scott Sheppard, a staff scientist at the Carnegie Institution for Science, and includes Jan Kleyna, a postdoctoral scholar at the University of Hawaii.

This article originally appeared in the UCLA Newsroom.