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.
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.
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.
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.
The enormous black hole at the center of our galaxy is having an unusually large meal of interstellar gas and dust, and researchers don’t yet understand why.
“We have never seen anything like this in the 24 years we have studied the supermassive black hole,” said Andrea Ghez, UCLA professor of physics and astronomy and a co-senior author of the research. “It’s usually a pretty quiet, wimpy black hole on a diet. We don’t know what is driving this big feast.”
The researchers analyzed more than 13,000 observations of the black hole from 133 nights since 2003. The images were gathered by the W.M. Keck Observatory in Hawaii and the European Southern Observatory’s Very Large Telescope in Chile. The team found that on May 13, the area just outside the black hole’s “point of no return” (so called because once matter enters, it can never escape) was twice as bright as the next-brightest observation.
They also observed large changes on two other nights this year; all three of those changes were “unprecedented,” Ghez said.
The brightness the scientists observed is caused by radiation from gas and dust falling into the black hole; the findings prompted them to ask whether this was an extraordinary singular event or a precursor to significantly increased activity.
“The big question is whether the black hole is entering a new phase — for example if the spigot has been turned up and the rate of gas falling down the black hole ‘drain’ has increased for an extended period — or whether we have just seen the fireworks from a few unusual blobs of gas falling in,” said Mark Morris, UCLA professor of physics and astronomy and the paper’s co-senior author.
The team has continued to observe the area and will try to settle that question based on what they see from new images.
“We want to know how black holes grow and affect the evolution of galaxies and the universe,” said Ghez, UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics. “We want to know why the supermassive hole gets brighter and how it gets brighter.”
The new findings are based on observations of the black hole — which is called Sagittarius A*, or Sgr A* — during four nights in April and May at the Keck Observatory. The brightness surrounding the black hole always varies somewhat, but the scientists were stunned by the extreme variations in brightness during that timeframe, including their observations on May 13.
“The first image I saw that night, the black hole was so bright I initially mistook it for the star S0-2, because I had never seen Sagittarius A* that bright,” said UCLA research scientist Tuan Do, the study’s lead author. “But it quickly became clear the source had to be the black hole, which was really exciting.”
One hypothesis about the increased activity is that when a star called S0-2 made its closest approach to the black hole during the summer 2018, it launched a large quantity of gas that reached the black hole this year.
Another possibility involves a bizarre object known as G2, which is most likely a pair of binary stars, which made its closest approach to the black hole in 2014. It’s possible the black hole could have stripped off the outer layer of G2, Ghez said, which could help explain the increased brightness just outside the black hole.
Morris said another possibility is that the brightening corresponds to the demise of large asteroids that have been drawn in to the black hole.
No danger to Earth
The black hole is some 26,000 light-years away and poses no danger to our planet. Do said the radiation would have to be 10 billion times as bright as what the astronomers detected to affect life on Earth.
Astrophysical Journal Letters also published a second article by the researchers, describing speckle holography, the technique that enabled them to extract and use very faint information from 24 years of data they recorded from near the black hole.
Ghez’s research team reported July 25 in the journal Science the most comprehensive test of Einstein’s iconic general theory of relativity near the black hole. Their conclusion that Einstein’s theory passed the test and is correct, at least for now, was based on their study of S0-2 as it made a complete orbit around the black hole.
Ghez’s team studies more than 3,000 stars that orbit the supermassive black hole. Since 2004, the scientists have used a powerful technology that Ghez helped pioneer, called adaptive optics, which corrects the distorting effects of the Earth’s atmosphere in real time. But speckle holography enabled the researchers to improve the data from the decade before adaptive optics came into play. Reanalyzing data from those years helped the team conclude that they had not seen that level of brightness near the black hole in 24 years.
“It was like doing LASIK surgery on our early images,” Ghez said. “We collected the data to answer one question and serendipitously unveiled other exciting scientific discoveries that we didn’t anticipate.”
Co-authors include Gunther Witzel, a former UCLA research scientist currently at Germany’s Max Planck Institute for Radio Astronomy; Mark Morris, UCLA professor of physics and astronomy; Eric Becklin, UCLA professor emeritus of physics and astronomy; Rainer Schoedel, a researcher at Spain’s Instituto de Astrofısica de Andalucıa; and UCLA graduate students Zhuo Chen and Abhimat Gautam.
The research is funded by the National Science Foundation, W.M. Keck Foundation, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, Lauren Leichtman and Arthur Levine, and Howard and Astrid Preston.
This article originally appeared in the UCLA Newsroom.
More than 100 years after Albert Einstein published his iconic theory of general relativity, it is beginning to fray at the edges, said Andrea Ghez, UCLA professor of physics and astronomy. Now, in the most comprehensive test of general relativity near the monstrous black hole at the center of our galaxy, Ghez and her research team report July 25 in the journal Science that Einstein’s theory of general relativity holds up.
“Einstein’s right, at least for now,” said Ghez, a co-lead author of the research. “We can absolutely rule out Newton’s law of gravity. Our observations are consistent with Einstein’s theory of general relativity. However, his theory is definitely showing vulnerability. It cannot fully explain gravity inside a black hole, and at some point we will need to move beyond Einstein’s theory to a more comprehensive theory of gravity that explains what a black hole is.”
Einstein’s 1915 theory of general relativity holds that what we perceive as the force of gravity arises from the curvature of space and time. The scientist proposed that objects such as the sun and the Earth change this geometry. Einstein’s theory is the best description of how gravity works, said Ghez, whose UCLA-led team of astronomers has made direct measurements of the phenomenon near a supermassive black hole — research Ghez describes as “extreme astrophysics.”
The laws of physics, including gravity, should be valid everywhere in the universe, said Ghez, who added that her research team is one of only two groups in the world to watch a star known as S0-2 make a complete orbit in three dimensions around the supermassive black hole at the center of the Milky Way. The full orbit takes 16 years, and the black hole’s mass is about 4 million times that of the sun.
The researchers say their work is the most detailed study ever conducted into the supermassive black hole and Einstein’s theory of general relativity.
The key data in the research were spectra that Ghez’s team analyzed last April, May and September as her “favorite star” made its closest approach to the enormous black hole. Spectra, which Ghez described as the “rainbow of light” from stars, show the intensity of light and offer important information about the star from which the light travels. Spectra also show the composition of the star. These data were combined with measurements Ghez and her team have made over the last 24 years.
Spectra — collected at the W.M. Keck Observatory in Hawaii using a spectrograph built at UCLA by a team led by colleague James Larkin — provide the third dimension, revealing the star’s motion at a level of precision not previously attained. (Images of the star the researchers took at the Keck Observatory provide the two other dimensions.) Larkin’s instrument takes light from a star and disperses it, similar to the way raindrops disperse light from the sun to create a rainbow, Ghez said.
“What’s so special about S0-2 is we have its complete orbit in three dimensions,” said Ghez, who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. “That’s what gives us the entry ticket into the tests of general relativity. We asked how gravity behaves near a supermassive black hole and whether Einstein’s theory is telling us the full story. Seeing stars go through their complete orbit provides the first opportunity to test fundamental physics using the motions of these stars.”
Ghez’s research team was able to see the co-mingling of space and time near the supermassive black hole. “In Newton’s version of gravity, space and time are separate, and do not co-mingle; under Einstein, they get completely co-mingled near a black hole,” she said.
“Making a measurement of such fundamental importance has required years of patient observing, enabled by state-of-the-art technology,” said Richard Green, director of the National Science Foundation’s division of astronomical sciences. For more than two decades, the division has supported Ghez, along with several of the technical elements critical to the research team’s discovery. “Through their rigorous efforts, Ghez and her collaborators have produced a high-significance validation of Einstein’s idea about strong gravity.”
Keck Observatory Director Hilton Lewis called Ghez “one of our most passionate and tenacious Keck users.” “Her latest groundbreaking research,” he said, “is the culmination of unwavering commitment over the past two decades to unlock the mysteries of the supermassive black hole at the center of our Milky Way galaxy.”
The researchers studied photons — particles of light — as they traveled from S0-2 to Earth. S0-2 moves around the black hole at blistering speeds of more than 16 million miles per hour at its closest approach. Einstein had reported that in this region close to the black hole, photons have to do extra work. Their wavelength as they leave the star depends not only on how fast the star is moving, but also on how much energy the photons expend to escape the black hole’s powerful gravitational field. Near a black hole, gravity is much stronger than on Earth.
Ghez was given the opportunity to present partial data last summer, but chose not to so that her team could thoroughly analyze the data first. “We’re learning how gravity works. It’s one of four fundamental forces and the one we have tested the least,” she said. “There are many regions where we just haven’t asked, how does gravity work here? It’s easy to be overconfident and there are many ways to misinterpret the data, many ways that small errors can accumulate into significant mistakes, which is why we did not rush our analysis.”
Ghez, a 2008 recipient of the MacArthur “Genius” Fellowship, studies more than 3,000 stars that orbit the supermassive black hole. Hundreds of them are young, she said, in a region where astronomers did not expect to see them.
It takes 26,000 years for the photons from S0-2 to reach Earth. “We’re so excited, and have been preparing for years to make these measurements,” said Ghez, who directs the UCLA Galactic Center Group. “For us, it’s visceral, it’s now — but it actually happened 26,000 years ago!”
This is the first of many tests of general relativity Ghez’s research team will conduct on stars near the supermassive black hole. Among the stars that most interest her is S0-102, which has the shortest orbit, taking 11 1/2 years to complete a full orbit around the black hole. Most of the stars Ghez studies have orbits of much longer than a human lifespan.
Ghez’s team took measurements about every four nights during crucial periods in 2018 using the Keck Observatory — which sits atop Hawaii’s dormant Mauna Kea volcano and houses one of the world’s largest and premier optical and infrared telescopes. Measurements are also taken with an optical-infrared telescope at Gemini Observatory and Subaru Telescope, also in Hawaii. She and her team have used these telescopes both on site in Hawaii and remotely from an observation room in UCLA’s department of physics and astronomy.
Black holes have such high density that nothing can escape their gravitational pull, not even light. (They cannot be seen directly, but their influence on nearby stars is visible and provides a signature. Once something crosses the “event horizon” of a black hole, it will not be able to escape. However, the star S0-2 is still rather far from the event horizon, even at its closest approach, so its photons do not get pulled in.)
Ghez’s co-authors include Tuan Do, lead author of the Science paper, a UCLA research scientist and deputy director of the UCLA Galactic Center Group; Aurelien Hees, a former UCLA postdoctoral scholar, now a researcher at the Paris Observatory; Mark Morris, UCLA professor of physics and astronomy; Eric Becklin, UCLA professor emeritus of physics and astronomy; Smadar Naoz, UCLA assistant professor of physics and astronomy; Jessica Lu, a former UCLA graduate student who is now a UC Berkeley assistant professor of astronomy; UCLA graduate student Devin Chu; Greg Martinez, UCLA project scientist; Shoko Sakai, a UCLA research scientist; Shogo Nishiyama, associate professor with Japan’s Miyagi University of Education; and Rainer Schoedel, a researcher with Spain’s Instituto de Astrofısica de Andalucıa.
The National Science Foundation has funded Ghez’s research for the last 25 years. More recently, her research has also been supported by the W.M. Keck Foundation, the Gordon and Betty Moore Foundation and the Heising-Simons Foundation; as well as Lauren Leichtman and Arthur Levine, and Howard and Astrid Preston.
In 1998, Ghez answered one of astronomy’s most important questions, helping to show that a supermassive black hole resides at the center of our Milky Way galaxy. The question had been a subject of much debate among astronomers for more than a quarter of a century.
A powerful technology that Ghez helped to pioneer, called adaptive optics, corrects the distorting effects of the Earth’s atmosphere in real time. With adaptive optics at Keck Observatory, Ghez and her colleagues have revealed many surprises about the environments surrounding supermassive black holes. For example, they discovered young stars where none was expected to be seen and a lack of old stars where many were anticipated. It’s unclear whether S0-2 is young or just masquerading as a young star, Ghez said.
In 2000, she and colleagues reported that for the first time, astronomers had seen stars accelerate around the supermassive black hole. In 2003, Ghez reported that the case for the Milky Way’s black hole had been strengthened substantially and that all of the proposed alternatives could be excluded.
In 2005, Ghez and her colleagues took the first clear picture of the center of the Milky Way, including the area surrounding the black hole, at Keck Observatory. And in 2017, Ghez’s research team reported that S0-2 does not have a companion star, solving another mystery.
This article originally appeared in the UCLA Newsroom.
Most people behave differently when under extreme pressure. Carbon and ice are no different.
Two new studies show how these key planetary ingredients take on exotic forms that could help researchers better understand the composition of Earth’s core as well as the cores of planets across the galaxy. Craig Manning, a UCLA professor of geology and geochemistry, is a co-senior author of one of the papers, which was published today in the journal Nature, and senior author of the other, which was published in Nature Communications in February.
The Nature Communications paper revealed that high pressure deep inside the young Earth may have driven vast stores of carbon into the planet’s core while also setting the stage for diamonds to form. In the Nature report, researchers found that water ice undergoes a complex crystalline metamorphosis as the pressure slowly ratchets up.
Scientists have long understood that the amount of carbon sequestered in present-day Earth’s rocks, oceans and atmosphere is always in flux because the planet shuffles the element around in a vast cycle that helps regulate climate. But researchers don’t know whether the Earth locked away even more carbon deep in its interior during its formative years — information that could reveal a little more about how our planet and others like it are built.
To pursue an answer to that question, Manning and colleagues calculated how carbon might have interacted with other atoms under conditions similar to those that prevailed roughly 4.5 billion years ago, when much of Earth was still molten. Using supercomputers, the team created simulations to explore what would happen to carbon at temperatures above 3,000 degrees Celsius (more than 5,400 degrees Fahrenheit) and at pressures more than 100,000 times of those on Earth’s surface today.
The experiment revealed that under those conditions, carbon tends to link up with iron, which implies that there might be considerable quantities of carbon sealed in Earth’s iron core today. Researchers had already suspected that in the young planet’s magma ocean, iron atoms hooked up with one another and then dropped to the planet’s center. But the new research suggests that this molten iron rain may have also dragged carbon down with it. Until now, researchers weren’t even sure whether carbon exists down there.
The team also found that as the pressure ramps up, carbon increasingly bonds with itself, forming long chains of carbon atoms with oxygen atoms sticking out.
“These complex chains are a form of carbon bonding that we really hadn’t anticipated at these conditions,” Manning said.
Such molecules could be a precursor to diamonds, which consist of many carbon atoms linked together.
Solving an icy enigma
The machinations of carbon under pressure provide clues as to how Earth-like planets are built. Frozen planets and moons in other solar systems, however, may also have to contend with water ice. In a separate paper, Manning and another team of scientists looked at how the molecular structure of extremely cold ice changes when put under intense pressure.
Under everyday conditions, water ice is made up of molecules laid out in honeycomb-like mosaics of hexagons. But when ice is exposed to crushing pressure or very low temperature — in labs or possibly deep inside remote worlds — the molecules can assume a bewildering variety of patterns.
One of those patterns, known as amorphous ice, is an enigma. In amorphous ice, the water molecules eschew rigid crystalline order and take on a free-form arrangement. Manning and colleagues set out to try and understand how amorphous ice forms.
First, they chilled normal ice to about 170 degrees below zero Celsius (about 274 degrees below zero Fahrenheit). Then, they locked the ice in the jaws of a high-tech vice grip inside a cryogenic vacuum chamber. Finally, over the span of several hours, they slowly stepped up the pressure in the chamber to about 15,000 times atmospheric pressure. They stopped raising the pressure periodically to fire neutrons through the ice so that they could see the arrangement of the water molecules.
Surprisingly to the researchers, the amorphous ice never formed. Instead, the molecules went through a series of previously known crystalline arrangements.
However, when the researchers conducted the same experiment but raised the pressure much more rapidly — this time in just 30 minutes — amorphous ice formed as expected. The results suggest that time is the secret ingredient: When pressure increases slowly, tiny seeds of crystalline ice have time to form and take over the sample. Otherwise, those seeds never get a chance to grow.
The findings, published May 23 in the journal Nature, could be useful to researchers who study worlds orbiting other suns and are curious about what conditions might be like deep inside frozen planets.
“It’s entirely likely that there are planets dominated by ice in other solar systems that could obtain these pressures and temperatures with ease,” Manning said. “We have to have this right if we’re going to have a baseline for understanding the interiors of cold worlds that may not be like Earth.”
Both papers were funded in part by the Deep Carbon Observatory, a 10-year program started in 2009 to investigate the quantities, movements, forms and origins of deep carbon inside Earth. The Nature Communications paper was also funded by the European Research Council and was co-authored by researchers at the Ecole Normale Supérieure de Lyon in France, one of whom — Natalia Solomatova — completed her undergraduate studies at UCLA. The Nature paper was co-authored by UCLA geologist Adam Makhluf and researchers from Oak Ridge National Laboratory and the National Research Council of Canada.
This article originally appeared on the UCLA Newsroom.
The center of our galaxy is a frenzy of activity. A behemoth black hole — 4 million times as massive as the sun — blasts out energy as it chows down on interstellar detritus while neighboring stars burst to life and subsequently explode.
Now, an international team of astronomers has discovered two exhaust channels — dubbed “galactic center chimneys” — that appear to funnel matter and energy away from the cosmic fireworks in the Milky Way’s center, about 28,000 light-years from Earth.
Mark Morris, a UCLA professor of astronomy and astrophysics, contributed to the research, which will be published March 21 in the journal Nature.
“We hypothesize that these chimneys are exhaust vents for all the energy released at the center of the galaxy,” Morris said.
All galaxies are giant star-forming factories, but their productivity can vary widely — from one galaxy to the next and even over the course of each galaxy’s lifetime. One mechanism for throttling the rate of star production is the fountain of matter and energy whipped up by the heavyweight black hole that lurks at a galaxy’s center.
“Star formation determines the character of a galaxy,” Morris said. “And that’s something we care about because stars produce the heavy elements out of which planets — and life — are made.”
To better understand what becomes of that outflow of energy, Morris and his colleagues pointed the European Space Agency’s XMM-Newton satellite, which detects cosmic X-rays, toward the center of the Milky Way. Because X-rays are emitted by extremely hot gas, they are especially useful for mapping energetic environments in space.
In images they collected from 2016 to 2018 and in 2012, the researchers found two plumes of X-rays — the galactic center chimneys — stretching in opposite directions from the central hub of the galaxy. Each plume originates within about 160 light-years of the supermassive black hole and spans over 500 light-years.
The chimneys hook up to two gargantuan structures known as the Fermi bubbles, cavities carved out of the gas that envelops the galaxy. The bubbles, which are filled with high-speed particles, straddle the center of the galaxy and stretch for 25,000 light-years in either direction. Some astronomers suspect that the Fermi bubbles are relics of massive eruptions from the supermassive black hole, while others think the bubbles are blown out by hordes of newly born stars. Either way, the chimneys could be the conduits through which high-speed particles get there.
Understanding how energy makes its way from a galaxy’s center to its outer limits could provide insights into why some galaxies are bursting with star formation whereas others are dormant.
“In extreme cases, that fountain of energy can either trigger or shut off star formation in the galaxy,” Morris said.
Our galaxy isn’t quite that extreme — other galaxies have fountains powered by central black holes weighing a thousand times more than ours — but the Milky Way’s center provides an up-close look at what might be happening in galaxies that are more energetic.
“We know that outflows and winds of material and energy emanating from a galaxy are crucial in sculpting and altering that galaxy’s shape over time — they’re key players in how galaxies, and other structures, form and evolve throughout the cosmos,” said lead author Gabriele Ponti of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. “Luckily, our galaxy gives us a nearby laboratory to explore this in detail, and probe how material flows out into the space around us.”
Morris said the centers of the nearest galaxies are hundreds to thousands of times farther away than our own. “The amount of energy coming out of the center of our galaxy is limited, but it’s a really good example of a galactic center that we can observe and try to understand,” he said.
Nine authors from five countries contributed to the study. The research was funded by NASA, the French National Center for Space Studies, the French National Agency for Research, the German Federal Ministry of Economics and Technology, the German Aerospace Center and the Max Planck Society.
Five years ago, a group of UCLA undergrads came together with a common goal — to build a small satellite and launch it into space. In the years since, more than 250 students — many of whom are now UCLA graduate students and alumni — have been the mechanical engineers, software developers, thermal and power testers, electronics technicians, mission planners and fabricators of the twin Electron Losses and Fields Investigation CubeSats, known as ELFIN.
Although UCLA has been building space instruments for NASA and other international space missions for more than 40 years, and members of its faculty have been critical contributors to space science, ELFIN is the first satellite mission built, managed and operated entirely at UCLA. And even more impressive, just about all of it has been done by the students.
This week, dozens of ELFINers (a nickname earned by those who’ve worked on the satellites), will drive about 150 miles up the California coast from Los Angeles to Vandenberg Air Force Base near Lompoc, to watch the product of their effort ascend into orbit.
“Just seeing all the hundreds of hours of work, that not just myself but others too, have put into this project, the many sleepless nights, the stressing out that you’re not going to make a deadline — just seeing it go up there … I’m probably going to cry,” said Jessica Artinger, an astrophysics major and geophysics and planetary science minor who will begin her fifth year this fall.
The two micro-satellites, each weighing about eight pounds and roughly the size of a loaf of bread, will help scientists better understand magnetic storms in near-Earth space. These storms are a typical form of “space weather” that is induced by solar activity, including flares and violent solar eruptions. Some solar outbursts can impact Earth, generating large amounts of invisible electromagnetic energy that transforms our local space environment.
“Magnetic storms are not just interesting space phenomena. They can energize electrons to high energies that can damage or even destroy orbiting satellites we depend on for GPS, communications and weather monitoring,” said Margaret Kivelson, UCLA professor emeritus of space physics. “They can also enhance space electrical currents which flow onto Earth, and could damage the power grid. Space weather research is also crucial for space tourism and space exploration.”
Currently, scientists’ ability to accurately model and predict space weather is in its infancy, just like meteorology was at the turn of the last century. ELFIN will make headway toward better understanding these phenomena.
ELFIN will go up as a secondary payload with the ICESat-2 mission at dawn on Saturday, Sept. 15, aboard the trusted Delta II, the final and hopefully 100th consecutive successful launch of this type of rocket. The launch will be streamed live on NASA TV’s YouTube channel, as well as on UCLA social media (follow #uclaELFIN).
Following the launch, many ELFINers at Vandenberg will come back to the campus command center to eagerly await the first Bruin transmissions from space, which are expected about 10 hours after blast-off. UCLA students will be directly involved in day-to-day mission activities and will have privileged access to ELFIN’s data. They will track and command the satellite via a custom-built antenna atop Knudsen Hall and will download data directly to the mission operations center located in the Earth, planetary and space sciences department. The ELFIN website will have interactive tools so the public can track and listen to the spacecraft as it passes overhead twice a day. The CubeSats are expected to remain in space for two years, after which they will gradually fall out of orbit and burn up in the atmosphere like shooting stars.
In fall 2017, as head of ELFIN’s fabrication team, Artinger led a small team that worked tirelessly in the EPSS prototyping lab using band saws, drill presses and a CNC machine (which is used to carve and smooth metal parts) to meticulously craft tightly toleranced components to meet their completion deadline.
“There was a lot of working things out in your head before machining it, especially for safety reasons,” said Artinger, who gave a final inspection by painstakingly sanding each part and then re-measuring each and every hole, comparing them to the technical drawings for accuracy before sending them upstairs to the mechanical team for assembly. The aerospace-grade tolerance requirement across the 13.5-inch long spacecraft, she said, was two thousandths of an inch — about half the thickness of a standard sheet of paper. The team also had to machine the sensitive energetic particle detector frames to an incredibly precise 1/10,000 of an inch, she said.
Artinger, a transfer student who graduated from Orange Coast College in 2016, plans to become a community college professor and can’t wait to use her ELFIN experience to inspire a new generation of students. She says ELFIN really opened her eyes to the power of mentoring through research and further solidified her commitment to teaching topics related to space science.
“Maybe we can discover something at the community college I’ll be working at using the actual data from the satellite that I helped build,” she said. “That would be really cool.”
Ethan Tsai learned about ELFIN when he was a UCLA sophomore. Despite having no background in space science, the former physics major started to work on simple tasks and gained the necessary skills to become the project’s attitude determination and control subsystem lead. Now studying for his master’s in electrical engineering, Tsai is ELFIN’s project manager.
“I was pretty honored to be able to work on a mission like this,” he said, adding that he never imagined being involved in a NASA mission as an undergraduate. “It wasn’t until about two years into the project that I started to understand and appreciate the quality of the work we were doing and how it’s going to actually affect not just our mission and the students around us but the scientific community as a whole.”
Tsai said he’s excited about the infrastructure he has helped create to make UCLA a “space campus,” supporting students who will work on future satellite missions.
The project has been supported with funding from the National Science Foundation and NASA, with technical assistance from the Aerospace Corporation among other industry partners and universities.
Those who have witnessed the aurora borealis and australis illuminate the skies, also known as the northern and southern lights, have experienced the beauty and power of space weather, likely without even knowing it.
“The aurora is sort of a TV screen that shows us what happens out in space.” said Vassilis Angelopoulos, a UCLA space physicist who got his doctorate at UCLA and serves as ELFIN’s principal investigator. “Space physicists can tell if something interesting or important is going on in space by looking at the aurora.”
ELFIN aims to observe the complex sequence whereby magnetic storms form waves near Earth, accelerating and forcing electrons to fall into the atmosphere, while a network of all-sky cameras across North America captures the resulting brightening of the auroral lights. The field of space science benefits from multi-satellite missions like ELFIN because of the ever-growing need to know about the dynamic conditions in space.
“Just like with atmospheric weather,” Angelopoulos said, “you need multiple space weather buoys to feed their data into our space weather models and be able to make predictions of conditions in the future.”
CubeSats fill this need because of their compact size, relative affordability ($300,000 compared to several hundred million dollars for a typical research satellite), and how quickly a team can go from prototyping to launch compared to standard-sized satellites. CubeSats uniquely allow students to witness end-to-end satellite mission development, testing and operations all within the span of their undergraduate studies.
For ELFINers, being part of an endeavor of this magnitude is reward enough, but working on this project also has professional and scientific benefits, Angelopoulos said. In addition to the leadership, interpersonal, problem-solving and technical skills they’ve developed, ELFINers are also contributing to the production of knowledge, something that is incredibly valuable to society and to their careers as scientists and engineers.
“As a researcher it’s important to not just analyze data that others collect, but to be involved in designing your own unique experiments to explore new key science questions. This is how space science started, with experiments on small rockets where students were involved in the nuts and bolts of them, and similarly with CubeSats, this is where the future of space science education is headed now,” Angelopoulos said.
Building on the opportunities that exist here at UCLA, and knowing the impact that experiential learning can have on a student’s academic life, Angelopoulos wanted to find a way to bring CubeSat development into the undergraduate experience.
“CubeSats are ideal because they create an environment where students from all walks of life, from all disciplines, can come together and practice what they’ve learned during their formal education in the context of a realistic environment,” Angelopoulos said. “This is exactly what academia, industry and research organizations around the country need — and they tell us that. This is the kind of experience they want in people who are applying to graduate school or who are applying to work in industrial firms because these are people who think on their feet and innovate.”
For the dozens of UCLA students, faculty, staff and alumni braving the chilly temperatures near Vandenberg Air Force Base on Saturday morning, the brilliant ray of white that radiated across the predawn horizon was the best goodbye ever.
At 6:02 a.m. a Delta II rocket lifted off from the base in Lompoc, California, carrying ELFIN — twin micro-satellites, each weighing about eight pounds and roughly the size of a loaf of bread — into orbit aboard NASA’s ICESat-2 mission.
Saturday’s launch was the culmination of years of planning, dreaming, fabricating, designing, assembling, testing and programming, virtually all of it done by more than 250 UCLA students, most of whom were undergraduates.
“It’s really been a very emotional moment for a lot of students here,” said Ethan Tsai, UCLA graduate student in electrical engineering and ELFIN’s project manager. Tsai, more than two dozen other current students, alumni and faculty, including Vassilis Angelopoulos, professor of space physics and ELFIN’s principal investigator, watched from the VIP area.
“There’s half of my brain that’s trying to stick with the professional mode … and then part of me is just like I can’t believe this thing is launching and I can’t believe this thing is in space,” Tsai said. “I don’t know that it’s sunk in yet. But it’s really emotional for me.”
Luis Frausto, 34, a 2010 UCLA mechanical engineering graduate, who worked on early prototypes of ELFIN, said he was in “total awe” watching the launch from a public viewing site near Vandenberg Middle School.
Frausto, now a design engineer at TAE Technologies, Inc., was one of more than 200 (a record for the Vandenberg public viewing site, according to a base spokesman) who braved the chilly temperatures, including about 40 UCLA ELFINers and a few of their friends, who counted down to zero as the launch went off, sending the crowd into cheers and applause.
“You can’t compare it to watching it on TV. It was like a feeling inside my chest, like I was out of breath,” said Frausto, who left his home in Irvine at 12:30 a.m. to drive the 200 miles northwest to Lompoc. “I’m here and I’m honored to be around everyone who worked on ELFIN.”
ELFIN, which stands for Electron Losses and Fields Investigation CubeSats, is designed to help scientists better understand magnetic storms in near-Earth space. These storms are a typical form of “space weather” that is induced by solar activity, including flares and violent solar eruptions. Magnetic storms can result in damage or even destruction of orbiting satellites that humans depend on for GPS, communications and weather monitoring. Space weather research is also crucial for space tourism and space exploration.
Another former ELFINer who came out was Mike Lawson, who works at the Jet Propulsion Laboratory in Pasadena on the Mars 2020 mission. Lawson slept only two hours on a couch at UCLA before he left Westwood at midnight for what he described as an “emotional” drive on U.S. 101 that included listening to David Bowie’s “Starman.”
“It’s weird. It’s surreal. It was 10 years gone in like 20 seconds,” said Lawson, who earned his bachelor’s degree and Ph.D. in geology from UCLA. The 37-year-old was one of the original ELFINers 10 years ago who worked on prototypes for what would become the satellites that launched this morning. Work began five years ago on the actual satellites that went into orbit, aboard NASA’s final Delta II rocket mission.
Jessica Artinger, an astrophysics major who will begin her fifth year at UCLA this fall, left at 1 a.m. from Fountain Valley in Orange County to make the trip. Since fall quarter 2017, Artinger has led the fabrication team.
“Watching this,” said Artinger, who prior to the launch had expected to cry but despite the dry eyes was nevertheless moved, “my time here means something.”
Louise Tamondong, who is part of ELFIN’s flight operations team, said she got chills watching the launch, which was easily visible for just a few seconds before the rocket was shrouded in thick clouds. About 10 seconds after the sky lit up, the crowd finally heard the roar of the rocket’s engines.
“It felt so unreal that everything that we worked for is going into space … it only felt real when we saw that bright light and everything going up,” said Tamondong. After liftoff, she headed back to Westwood to listen for the first signal from the orbiting ELFIN through an antenna on the roof of UCLA’s Knudsen Hall. They received a signal around 4:30 p.m., confirming that both probes survived the bumpy ride to orbit. The team will now begin commissioning the spacecraft systems and instruments to prepare for the science operations phase.
As a new Bruin, Sixue Xu wasn’t part of the team that designed, tested and built ELFIN. But the graduate student in space physics will be among those who stand to benefit from ELFIN’s work.
“Now it’s our turn,” Xu said, “to make that data into science.”
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