SPACE
Study delivers detailed photos of galaxies’ inner structures
JWST data reveals how dust, gas assemble to form galactic disks
COLUMBUS, Ohio – For the first time, high-resolution images captured by the James Webb Space Telescope are offering powerful insights into the complex dust patterns of nearby star-forming galaxies.
One of the most fundamental building blocks in the universe, cosmic dust is a vital ingredient to the growth of a galaxy. When scattered, these tiny grains help plant the seeds for the creation of stars and planets alike – yet only recently, through rapid leaps in technology, have astronomers begun to shine a brighter light on their intricate physics.
Led by scientists at The Ohio State University, an international team of astronomers used data collected by the James Webb Space Telescope’s Mid-Infrared Instrument to create stunning visuals of 19 spiral galaxies located relatively close to the Milky Way. By examining infrared light – wavelengths invisible to the naked eye – these incredibly precise images reveal how dust fertilizes the universe after being heated by both massive young stars and surrounding interstellar space radiation.
“Using this brand new data, we’re able to see the distribution of dust emission and determine what the interstellar material in the disks of these galaxies looks like,” said Debosmita Pathak, lead author of the study and a graduate student in astronomy at Ohio State.
The images were taken from the PHANGS-JWST Cycle 1 Treasury, a survey collaboration that uses high-powered telescopes to better understand galactic evolution. In this study, they used data collected from the first year of Webb observations to create probability distribution function (PDF) measurements that chart the galaxies’ dust emissions in the mid-infrared.
They found that the disks of galaxies in the mid-infrared show both a normal distribution of gas (represented in the study’s PDF charts as a high peak) and a high distribution (appearing as a gentle slope). While the regions where star-forming nurseries reside look noticeably different, the shape and width of the distribution of diffuse gas in these galaxies stayed consistent.
“Dynamically, they’ve all got very different things going on in the centers,” said Pathak. “But once you take the centers out of the picture, the disks of these galaxies look very similar to each other.”
The study, published recently in The Astronomical Journal, suggests that because the patterns of infrared light emitted by these observed galaxies seem to be uniform, the density of the gas inside galactic disks follows a specific pattern even when shaped by very different galactic environments. “Because this dust traces out the fuel for future generations of stars,” Pathak said, “the similarity we see among galaxies hints that some aspects of star and planet formation may be universal across galaxies.”
By illuminating another clue about the mysteries of our universe, these galactic snapshots also provide an opportunity for humans to take a look in the cosmic mirror, Pathak said.
“It’s hard for us to get a global perspective of the Milky Way,” said Pathak. “This study tells us that if you looked at it as an outsider, you would see something similar to what we saw for a bunch of other nearby galaxies.”
Moreover, deepening our current understanding of the structure of nearby galaxies could lead to a better grasp of astrophysics, including how various objects in the universe fit together.
Ultimately, once more data becomes available after the next few JWST cycles, the team plans to redo much of the work with an even larger and richer sample size.
“You can’t observe all galaxies in the universe at such high resolutions, so it helps to be able to make quantitative statements about them in general, because that allows us to extrapolate about more and more galaxies in the future,” said Pathak.
This study was supported by the National Science Foundation, the Alexander von Humboldt Foundation, the Heising-Simons Foundation, the Natural Sciences and Engineering Research Council of Canada (NSERC), and the Simons Foundation. Other Ohio State co-authors were Adam K. Leroy, Todd A. Thompson and Laura A. Lopez.
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Contact: Debosmita Pathak, Pathak.89@osu.edu
Written by: Tatyana Woodall, Woodall.52@osu.edu
JOURNAL
The Astronomical Journal
METHOD OF RESEARCH
Imaging analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
A Two-Component Probability Distribution Function Describes the Mid-IR Emission from the Disks of Star-forming Galaxies
Origin of intense light in supermassive black holes and tidal disruption events revealed
THE HEBREW UNIVERSITY OF JERUSALEM
IMAGE:
A STAR IN THE MIDST OF BEING DISRUPTED BY A SUPERMASSIVE BLACK HOLE. AS THE STAR WANDERS PAST THE SUPER MASSIVE BLACK HOLE, THE TIDAL FIELD OF THE BLACK HOLE RIPS APART THE STAR. HALF OF THE STAR IS FLUNG AWAY TO INFINITY AND THE OTHER HALF FALLS BACK TO THE BLACK HOLE. THE PICTURE SHOWS THE RESULT OF THE SIMULATION CARRIED OUT BY STEINBERG AND STONE, SHOWING THE DENSITY OF THE INFALLING HALF (GREEN-BLUE COLOR) AS WELL AS THE HEAT THAT IS GENERATED BY THE SHOCKS (WHITE-RED).
view moreCREDIT: ELAD STEINBERG
A new study by Hebrew University is a significant breakthrough in understanding Tidal Disruption Events (TDEs) involving supermassive black holes. The new simulations, for the first time ever, accurately replicate the entire sequence of a TDE from stellar disruption to the peak luminosity of the resulting flare. This study has unveiled a previously unknown type of shockwave within TDEs, settling a longstanding debate about the energy source of the brightest phases in these events. It confirms that shock dissipation powers the brightest weeks of a TDE flare, opening doors for future studies to utilize TDE observations as a means to measure essential properties of black holes and potentially test Einstein's predictions in extreme gravitational environments.
[Jerusalem, Israel] – The mysteries of supermassive black holes have long captivated astronomers, offering a glimpse into the deepest corners of our universe. Now, a new study led by Dr. Elad Steinberg and Dr. Nicholas C. Stone at the Racah Institute of Physics, The Hebrew University, sheds new light on these enigmatic cosmic entities.
Supermassive black holes, ranging from millions to billions of times the mass of our Sun, have remained elusive despite their pivotal role in shaping galaxies. Their extreme gravitational pull warps spacetime, creating an environment that defies conventional understanding and presents a challenge for observational astronomers.
Enter Tidal Disruption Events (TDEs), a dramatic phenomenon that occurs when ill-fated stars venture too close to a black hole's event horizon, and are torn apart into thin streams of plasma. As this plasma returns towards the black hole, a series of shockwaves heat it up, leading to an extraordinary display of luminosity—a flare that surpasses the collective brightness of an entire galaxy for weeks or even months.
The study conducted by Steinberg and Stone represents a significant leap forward in understanding these cosmic events. For the first time, their simulations have recreated a realistic TDE, capturing the complete sequence from the initial star disruption to the peak of the ensuing luminous flare, all made possible by pioneering radiation-hydrodynamics simulation software developed by Steinberg at The Hebrew University.
This research has uncovered a previously unexplored type of shockwave within TDEs, revealing that these events dissipate their energy at a faster rate than previously understood. By clarifying this aspect, the study resolves a long-standing theoretical debate, confirming that the brightest phases of a TDE flare are powered by shock dissipation—a revelation that sets the stage for comprehensive exploration by observational astronomers.
These findings pave the way for translating TDE observations into precise measurements of crucial black hole properties, including mass and spin. Moreover, these cosmic occurrences could serve as a litmus test for validating Einstein's predictions in extreme gravitational environments.
Steinberg and Stone’s study not only unravels the intricate dynamics of TDEs but also opens a new chapter in our quest to comprehend the fundamental workings of supermassive black holes. Their simulations mark a crucial step towards harnessing these celestial events as invaluable tools for deciphering the cosmic mysteries lurking at the heart of galaxies.
Video: Disruption of solar mass star: https://www.youtube.com/watch?v=O3IWCPO_Thk
JOURNAL
Nature
METHOD OF RESEARCH
Computational simulation/modeling
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Stream-Disk Shocks as the Origins of Peak Light in Tidal Disruption Events
ARTICLE PUBLICATION DATE
17-Jan-2024
The metalens meets the stars
Large, all-glass metalens images sun, moon and nebulae
IMAGE:
IMAGE OF THE MOON TAKEN BY THE METALENS FROM THE ROOF A BUILIDNG IN CAMBRIDGE, MA.
view moreCREDIT: (CREDIT: CAPASSO LAB/HARVARD SEAS)
Metalenses have been used to image microscopic features of tissue and resolve details smaller than a wavelength of light. Now they are going bigger.
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a 10-centimeter-diameter glass metalens that can image the sun, the moon and distant nebulae with high resolution. It is the first all-glass, large-scale metalens in the visible wavelength that can be mass produced using conventional CMOS fabrication technology.
The research is published in ACS Nano.
“The ability to accurately control the size of tens of billions of nanopillars over an unprecedentedly large flat lens using state-of-the-art semiconductor foundry processes is a nanofabrication feat that opens exciting new opportunities for space science and technology,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper.
Most flat metalenses, which use millions of pillar-like nanostructures to focus light, are about the size of a piece of glitter. In 2019, Capasso and his team developed a centimeter-scale metalens using a technique called deep-ultraviolet (DUV) projection lithography, which projects and forms a nanostructure pattern that can be directly etched into the glass wafer, eliminating the time-consuming writing and deposition processes that were required for previous metalenses.
DUV projection lithography is commonly used to pattern fine lines and shapes in silicon chips for smartphones and computers. Joon-Suh Park, a former graduate student at SEAS and current postdoctoral fellow in Capasso's team, demonstrated that the technique could not only be used to mass produce metalenses but also increase their size for applications in virtual and augmented reality.
But making the metalens even larger for applications in astronomy and free-space optical communications posed an engineering problem.
“There is a major limitation with the lithography tool because these tools are used to make computer chips, so chip size is restricted to no more than 20 to 30 millimeters,” said Park, co-first author of the paper. “In order to make a 100-millimeter diameter lens, we needed to find a way around this limitation.”
Park and the team developed a technique to stitch together several patterns of nanopillars using the DUV projection lithography tool. By dividing the lens into 25 sections but using only the 7 sections of a quadrant considering the rotational symmetry, the researchers showed that DUV projection lithography could pattern 18.7 billion designed nanostructures onto a 10-centimeter circular area in a matter of minutes. The team also developed a vertical glass etching technique that allows the creation of high-aspect ratio, smooth-sidewall nanopillars etched into glass.
“Using the same DUV projection lithography, one could produce large-diameter, aberration-correcting meta-optics or even larger lenses on larger glass diameter wafers as the corresponding CMOS foundry tools become increasingly available in the industry,” said Soon Wei Daniel Lim, a postdoctoral fellow at SEAS and co-first author of the paper.
Lim played a lead role in the full simulation and characterization of all the possible fabrication errors that could arise during mass-manufacturing processes and how they could impact the optical performance of metalenses.
After addressing possible manufacturing challenges, the researchers demonstrated the power of the metalens in imaging celestial objects.
Mounting the metalens on a tripod with a color filter and camera sensor, Park and the team took to the roof of Harvard’s Science Center. There, they imaged the Sun, the moon and the North America nebula, a dim nebula in the constellation Cygnus about 2,590 light years away.
“We were able to get very detailed images of the Sun, the moon and the nebula that are comparable to images taken by conventional lenses” said Arman Amirzhan, a graduate student in the Capasso Lab and co-author of the paper.
Using only the metalens, the researchers were able to image the same cluster of sunspots as a NASA image taken that same day.
The team also demonstrated that the lens could survive exposure to extreme heat, extreme cold and the intense vibrations that would occur during a space launch without any damage or loss in optical performance.
Because of its size and monolithic glass composition, the lens could also be used for long-range telecommunications and directed energy transport applications.
The research is co-authored by Hyukmo Kang, Karlene Karrfalt, Daewook Kim, Joel Leger, Augustine Urbas, Marcus Ossiander and Zhaoyi Li. It was supported by the Defense Advanced Research Projects Agency (DARPA) Grant No. HR00111810001 and the Air Force Office of Scientific Research under Award No. FA9550-22-1-0312.
JOURNAL
ACS Nano
Metalens image of North American Nebula
Image of the North America Nebula, in the constellation Cygnus, taken by the metalens on the roof of the Science Center in Cambridge.
This 10-centimeter-diameter glass metalens can image the sun, the moon and distant nebulae with high resolution.
CREDIT
(Credit: Capasso Lab/Harvard SEAS)
Astronomers detect oldest black hole ever observed
Researchers have discovered the oldest black hole ever observed, dating from the dawn of the universe, and found that it is ‘eating’ its host galaxy to death.
The international team, led by the University of Cambridge, used the NASA/ESA/CSA James Webb Space Telescope (JWST) to detect the black hole, which dates from 400 million years after the big bang, more than 13 billion years ago. The results, which lead author Professor Roberto Maiolino says are “a giant leap forward”, are reported in the journal Nature.
That this surprisingly massive black hole – a few million times the mass of our Sun – even exists so early in the universe challenges our assumptions about how black holes form and grow. Astronomers believe that the supermassive black holes found at the centre of galaxies like the Milky Way grew to their current size over billions of years. But the size of this newly-discovered black hole suggests that they might form in other ways: they might be ‘born big’ or they can eat matter at a rate that’s five times higher than had been thought possible.
According to standard models, supermassive black holes form from the remnants of dead stars, which collapse and may form a black hole about a hundred times the mass of the Sun. If it grew in an expected way, this newly-detected black hole would take about a billion years to grow to its observed size. However, the universe was not yet a billion years old when this black hole was detected.
“It’s very early in the universe to see a black hole this massive, so we’ve got to consider other ways they might form,” said Maiolino, from Cambridge’s Cavendish Laboratory and Kavli Institute of Cosmology. “Very early galaxies were extremely gas-rich, so they would have been like a buffet for black holes.”
Like all black holes, this young black hole is devouring material from its host galaxy to fuel its growth. Yet, this ancient black hole is found to gobble matter much more vigorously than its siblings at later epochs.
The young host galaxy, called GN-z11, glows from such an energetic black hole at its centre. Black holes cannot be directly observed, but instead they are detected by the tell-tale glow of a swirling accretion disc, which forms near the edges of a black hole. The gas in the accretion disc becomes extremely hot and starts to glow and radiate energy in the ultraviolet range. This strong glow is how astronomers are able to detect black holes.
GN-z11 is a compact galaxy, about one hundred times smaller than the Milky Way, but the black hole is likely harming its development. When black holes consume too much gas, it pushes the gas away like an ultra-fast wind. This ‘wind’ could stop the process of star formation, slowly killing the galaxy, but it will also kill the black hole itself, as it would also cut off the black hole’s source of ‘food’.
Maiolino says that the gigantic leap forward provided by JWST makes this the most exciting time in his career. “It’s a new era: the giant leap in sensitivity, especially in the infrared, is like upgrading from Galileo’s telescope to a modern telescope overnight,” he said. “Before Webb came online, I thought maybe the universe isn’t so interesting when you go beyond what we could see with the Hubble Space Telescope. But that hasn’t been the case at all: the universe has been quite generous in what it’s showing us, and this is just the beginning.”
Maiolino says that the sensitivity of JWST means that even older black holes may be found in the coming months and years. Maiolino and his team are hoping to use future observations from JWST to try to find smaller ‘seeds’ of black holes, which may help them untangle the different ways that black holes might form: whether they start out large or they grow fast.
The research was supported in part by the European Research Council, the Royal Society, and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).
JOURNAL
Nature
ARTICLE TITLE
A small and vigorous black hole in the early Universe
ARTICLE PUBLICATION DATE
17-Jan-2024
New research shows that most early galaxies looked like breadsticks rather than pizza pies or dough balls
Data from NASA’s James Webb Space Telescope suggests that many early galaxies were long and thin, not disk-like or spherical.
Columbia researchers analyzing images from NASA’s James Webb Space Telescope have found that galaxies in the early universe are often flat and elongated, like breadsticks—and are rarely round, like balls of pizza dough. “Roughly 50 to 80% of the galaxies we studied appear to be flattened in two dimensions,” explained Viraj Pandya, a NASA Hubble Fellow at Columbia University, and the lead author of a new paper slated to appear in The Astrophysical Journal that outlines the findings. “Galaxies that look like long, thin breadsticks seem to be very common in the early universe, which is surprising, since they are uncommon among galaxies in the present-day universe.”
The team focused on a vast field of near-infrared images delivered by Webb, known as the Cosmic Evolution Early Release Science (CEERS) Survey, plucking out galaxies that are estimated to have existed when the universe was 600 million to 6 billion years old.
While most distant galaxies look like breadsticks, others are shaped like pizza pies and balls of pizza dough. The “balls of pizza dough,” or sphere-shaped galaxies, appear to be the smallest type of galaxy and were also the least frequently identified. The pizza pie-shaped galaxies were found to be as large as breadstick-shaped galaxies along their longest axis. “They are more common in the nearby universe which, due to the universe’s ongoing expansion, is made up of older, more mature galaxies.”
Which category would our Milky Way galaxy fall into if we were able to wind the clock back by billions of years? “Our best guess is that it might have appeared more like a breadstick,” said co-author Haowen Zhang, a PhD candidate at the University of Arizona in Tucson. This hypothesis is based partly on new evidence from Webb—theorists have “wound back the clock” to estimate the Milky Way’s mass billions of years ago, which suggests its likely breadstick shape in the distant past.
Images of what researchers believe are elongated, ellipsoid (i.e. breadstick-shaped) galaxies, captured with the James Webb Space Telescope. The word “believe” reflects the fact that some of the galaxies may be disk (i.e pizza pie) shaped galaxies seen from the side. (Credit: Viraj Pandya et al.)
These distant galaxies are also far less massive than nearby spirals and ellipticals—they are precursors to more massive galaxies like our own. “In the early universe, galaxies had had far less time to grow,” said Kartheik Iyer, a co-author and NASA Hubble Fellow also at Columbia University. “Identifying additional categories for early galaxies is exciting—there’s a lot more to analyze now. We can now study how galaxies’ shapes relate to how they look and better project how they formed in much more detail.”
Hubble, the space telescope that launched in 1990 and collects data to this day, “has long showed an excess of elongated galaxies,” explained co-author Marc Huertas-Company, a faculty research scientist at the Institute of Astrophysics on the Canary Islands. But researchers still wondered: Would additional detail show up better with the sensitivity to infrared light that the Webb telescope, which launched in 2021, has? “Webb confirmed that Hubble didn’t miss any additional features in the galaxies they both observed. Plus, Webb showed us many more distant galaxies with similar shapes, all in great detail,” Huertas-Company said.
One question, of course, is why early galaxies tended to be so flattened and elongated. One hypothesis, Pandya explained, is that the early universe may have been filled with filaments of dark matter that formed a kind of “skeletal background,” or “cosmic highway,” that ushered gas and stars along it. These filaments still exist, but they have grown much more diffuse as the universe has expanded, so they may be less likely to promote the formation of breadstick-shaped galaxies.
When researchers plotted galaxies’ aspect ratios against their longest axis length, they found the diagrams looked distinctly like bananas. (Credit: Pandya et al.)
The paper is called “Galaxies Going Bananas,” yet another food analogy that sprang into the authors’ minds as they looked at their data. When the authors plotted galaxies’ aspect ratios against their longest axis length, they found that the diagrams that emerged looked distinctly like bananas, a shape that reflects their elongated, ellipsoid (i.e. breadstick) shape. “The bananas are another way of saying that these intrinsically elongated galaxies seem to be the dominant ones in the first 4 billion years of the universe,” Pandya said.
There are still gaps in our knowledge. Researchers not only need an even larger sample size from Webb to further refine the properties and precise locations of distant galaxies, they will also need to spend ample time tweaking and updating their models to better reflect the precise geometries of distant galaxies. “These are early results,” said co-author Elizabeth McGrath, an associate professor at Colby College in Waterville, Maine. “We need to delve more deeply into the data to figure out what’s going on, but we’re very excited about these early trends.”
This article was adapted from a press release by NASA, which used the metaphor of pool noodles and surfboards to describe the paper’s findings.
JOURNAL
The Astrophysical Journal
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Galaxies Going Bananas
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