Testing a theory of supermassive black holes with 100 newly described 'blazars'
More than a hundred blazars—distant and active galaxies with a central supermassive black hole that drives powerful jets—have been newly characterized by Penn State researchers from a catalog of previously unclassified high-energy cosmic emissions. The new blazars, which are dim relative to more typical blazars, have allowed the researchers to test a controversial theory of blazar emissions, informing our understanding of black hole growth and even theories of general relativity and high-energy particle physics.
A paper describing the blazars and the theory has been accepted for publication in the Astrophysical Journal, and the peer-reviewed accepted version appears online on the preprint server arXiv.
Supermassive black holes can be millions or billions of times the mass of our sun. In some cases, matter outside of the black hole’s event horizon is propelled in a jet, accelerating to nearly the speed of light and sending emissions across the universe. When the jet happens to be pointed directly at the Earth, the system is typically called a blazar.
“Because the jet of a blazar is pointed directly at us, we can see them from much farther away than other black hole systems, similar to how a flashlight appears brightest when you’re looking directly at it,” said Stephen Kerby, graduate student in astronomy and astrophysics at Penn State and first author of the paper. “Blazars are exciting to study because their properties allow us to answer questions about supermassive black holes throughout the universe. In this study, we used relatively new methods to characterize 106 dim blazars and test the predictions of a contentious theory called the ‘blazar sequence.’”
Blazars emit light across the entire electromagnetic spectrum, from lower-energy wavelengths such as radio, infrared and visible light, up to higher-energy wavelengths like X-rays and gamma rays. When astronomers study observations of these emissions, they typically see two broad peaks, one in gamma rays and one at lower-energy wavelengths. The wavelengths and the intensity of these peaks varies from blazar to blazar and with time. An overarching theory of blazars defined by the “blazar sequence" predicts that the lower-energy peak for brighter blazars will, on average, be redder — lower energy — than that of dimmer blazars, while the lower-energy peak for dim blazars will be bluer — higher energy.
“Some of the most exciting and extreme blazars are discovered by detecting their gamma-ray emission, but we can’t usually classify or understand these objects without further multiwavelength observations,” said Abe Falcone, research professor of astronomy and astrophysics and the lead of a high energy astrophysics group at Penn State. “With our currently operating telescopes, it’s actually very difficult to detect and classify the lower-energy peaked — red — blazars that are also dim, whereas it is much easier to find these blazars when their peaks are at higher energies or when they are bright. So, with this research, we are minimizing a selection bias and exploring the blazar sequence by delving deeper into lower luminosities of both the low-energy and high-energy peaked blazars.”
The researchers, alongside Amanpreet Kaur — associate research professor of astronomy and astrophysics at Penn State at the time of the research — previously identified potential blazars from a catalog of gamma-ray sources detected by the Fermi Large Area Telescope, many of which had not yet been paired up with lower-energy emissions that may have come from the same source. For each of the blazars, the researchers then identified these counterpart emissions in X-ray, UV, and optical — detected by the Neil Gehrels Swift Observatory, whose Mission Operations Center is located at Penn State — and in infrared and radio emissions from archival data. Cross-referencing the information ultimately allowed the researchers to characterize the spectra of 106 new, dim blazars.
“The Swift telescope observations allowed us to pinpoint the positions of these blazars with much more precision than with the Fermi data alone,” said Kerby. “Pulling together all this emission data, combined with two new technical approaches, helped us identify where in the electromagnetic spectrum the low-energy peak occurs for each of the blazars, which, for example, can provide information about the strength of the jet’s magnetic field, how fast the charged particles are moving, and other information.”
To identify where this peak occurred for the dim blazars, the researchers used machine-learning approach and direct physical fitting approaches, each of which, according to Kerby, has advantages and disadvantages. The machine-learning approach filters out emissions that might actually be noise, such as from dust in the galaxy or light from other stars. The direct physical fitting approach does not filter out noise and is considerably more difficult to use but provides more detailed properties of the blazar jet.
“For both approaches, the emissions of our sample of dim blazars generally peaks in the blue, higher-energy light, though the fitting approach produced less extreme values,” said Kerby. “This is in agreement with the blazar sequence and extends what we know about this pattern. However, there are still a thousand Fermi unassociated sources for which we have found no X-ray counterpart, and it’s a fairly safe assumption that many of those sources are also blazars that are just too dim in the X-rays for us to detect. We can use the lessons we’ve learned here about the shape of these blazar’s spectra to make predictions about the blazars that are still too dim for us to detect, which would further test the blazar sequence.”
The catalog of new blazars is available for other astronomers to study in detail.
“It’s important to always work to expand our datasets to reach dimmer and dimmer sources, because it makes our theories more complete and less prone to failures from unexpected biases,” said Kerby. “I’m excited for new telescopes to probe even dimmer blazars in the future.”
According to the researchers, studying supermassive black holes also provides a unique way to understand the physical theories in the universe.
“Supermassive black holes, and their surroundings, are cosmic laboratories that are far more energetic than anything we can produce in particle accelerators on Earth,” said Falcone. “They provide us with opportunities to study theories of relativity, to better understand how particles behave at high energies, to study potential sources of cosmic rays that arrive here on Earth, and to study the evolution and formation of supermassive black holes and their jets."
The research was supported by NASA.
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Gravitational Wave Detector LIGO is Back Online after 3 Years of Upgrades
After a three-year hiatus, scientists in the U.S. have just turned on detectors capable of measuring gravitational waves – tiny ripples in space itself that travel through the universe.
Unlike light waves, gravitational waves are nearly unimpeded by the galaxies, stars, gas and dust that fill the universe. This means that by measuring gravitational waves, astrophysicists like me can peek directly into the heart of some of these most spectacular phenomena in the universe.
Since 2020, the Laser Interferometric Gravitational-Wave Observatory – commonly known as LIGO – has been sitting dormant while it underwent some exciting upgrades. These improvements will significantly boost the sensitivity of LIGO and should allow the facility to observe more-distant objects that produce smaller ripples in spacetime.
By detecting more events that create gravitational waves, there will be more opportunities for astronomers to also observe the light produced by those same events. Seeing an event through multiple channels of information, an approach called multi-messenger astronomy, provides astronomers rare and coveted opportunities to learn about physics far beyond the realm of any laboratory testing.
According to Einstein’s theory of general relativity, mass and energy warp the shape of space and time. The bending of spacetime determines how objects move in relation to one another – what people experience as gravity.
Gravitational waves are created when massive objects like black holes or neutron stars merge with one another, producing sudden, large changes in space. The process of space warping and flexing sends ripples across the universe like a wave across a still pond. These waves travel out in all directions from a disturbance, minutely bending space as they do so and ever so slightly changing the distance between objects in their way.
Even though the astronomical events that produce gravitational waves involve some of the most massive objects in the universe, the stretching and contracting of space is infinitesimally small. A strong gravitational wave passing through the Milky Way may only change the diameter of the entire galaxy by three feet (one meter).
The first gravitational wave observations Though first predicted by Einstein in 1916, scientists of that era had little hope of measuring the tiny changes in distance postulated by the theory of gravitational waves.
Around the year 2000, scientists at Caltech, the Massachusetts Institute of Technology and other universities around the world finished constructing what is essentially the most precise ruler ever built – the LIGO observatory.
LIGO is comprised of two separate observatories, with one located in Hanford, Washington, and the other in Livingston, Louisiana. Each observatory is shaped like a giant L with two, 2.5-mile-long (four-kilometer-long) arms extending out from the center of the facility at 90 degrees to each other.
To measure gravitational waves, researchers shine a laser from the center of the facility to the base of the L. There, the laser is split so that a beam travels down each arm, reflects off a mirror and returns to the base. If a gravitational wave passes through the arms while the laser is shining, the two beams will return to the center at ever so slightly different times. By measuring this difference, physicists can discern that a gravitational wave passed through the facility.
LIGO began operating in the early 2000s, but it was not sensitive enough to detect gravitational waves. So, in 2010, the LIGO team temporarily shut down the facility to perform upgrades to boost sensitivity. The upgraded version of LIGO started collecting data in 2015 and almost immediately detected gravitational waves produced from the merger of two black holes.
Since 2015, LIGO has completed three observation runs. The first, run O1, lasted about four months; the second, O2, about nine months; and the third, O3, ran for 11 months before the COVID-19 pandemic forced the facilities to close. Starting with run O2, LIGO has been jointly observing with an Italian observatory called Virgo.
Between each run, scientists improved the physical components of the detectors and data analysis methods. By the end of run O3 in March 2020, researchers in the LIGO and Virgo collaboration had detected about 90 gravitational waves from the merging of black holes and neutron stars.
The observatories have still not yet achieved their maximum design sensitivity. So, in 2020, both observatories shut down for upgrades yet again.
Scientists have been working on many technological improvements.
One particularly promising upgrade involved adding a 1,000-foot (300-meter) optical cavity to improve a technique called squeezing. Squeezing allows scientists to reduce detector noise using the quantum properties of light. With this upgrade, the LIGO team should be able to detect much weaker gravitational waves than before.
My teammates and I are data scientists in the LIGO collaboration, and we have been working on a number of different upgrades to software used to process LIGO data and the algorithms that recognize signs of gravitational waves in that data. These algorithms function by searching for patterns that match theoretical models of millions of possible black hole and neutron star merger events. The improved algorithm should be able to more easily pick out the faint signs of gravitational waves from background noise in the data than the previous versions of the algorithms.
In early May 2023, LIGO began a short test run – called an engineering run – to make sure everything was working. On May 18, LIGO detected gravitational waves likely produced from a neutron star merging into a black hole.
LIGO’s 20-month observation run 04 will officially start on May 24, and it will later be joined by Virgo and a new Japanese observatory – the Kamioka Gravitational Wave Detector, or KAGRA.
While there are many scientific goals for this run, there is a particular focus on detecting and localizing gravitational waves in real time. If the team can identify a gravitational wave event, figure out where the waves came from and alert other astronomers to these discoveries quickly, it would enable astronomers to point other telescopes that collect visible light, radio waves or other types of data at the source of the gravitational wave. Collecting multiple channels of information on a single event – multi-messenger astrophysics – is like adding color and sound to a black-and-white silent film and can provide a much deeper understanding of astrophysical phenomena.
Astronomers have only observed a single event in both gravitational waves and visible light to date – the merger of two neutron stars seen in 2017. But from this single event, physicists were able to study the expansion of the universe and confirm the origin of some of the universe’s most energetic events known as gamma-ray bursts.
With run O4, astronomers will have access to the most sensitive gravitational wave observatories in history and hopefully will collect more data than ever before. My colleagues and I are hopeful that the coming months will result in one – or perhaps many – multi-messenger observations that will push the boundaries of modern astrophysics.
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Brightest gamma-ray burst ever recorded may be 1-in-10,000-year event
On Sunday, Oct. 9, 2022, a pulse of intense radiation swept through the solar system. It was so exceptional that astronomers quickly dubbed it the “BOAT”—the brightest of all time. The source was a gamma-ray burst (GRB), the most powerful class of explosions in the universe.
The burst triggered detectors on numerous spacecraft, including the Neil Gehrels Swift Observatory, whose Mission Operations Center is located at Penn State.
“When we first detected the burst, it was so bright and so close that we didn’t actually think it was a gamma-ray burst,” said Maia Williams, a research technologist at Penn State and a member of the Swift team. “But observations from NASA’s Fermi Gamma-ray Space Telescope and other observatories confirmed that this was indeed from a uniquely bright gamma-ray burst.”
After the initial detections, observatories around the globe followed up. After combing through all of this data, astronomers can now characterize just how bright it was and better understand its scientific impact.
“GRB 221009A was likely the brightest burst at X-ray and gamma-ray energies to occur since human civilization began,” said Eric Burns, an assistant professor of physics and astronomy at Louisiana State University in Baton Rouge. He led an analysis of some 7,000 GRBs detected by various observatories to establish how frequently events this bright may occur. Their answer: once in every 10,000 years.
Burns and other scientists presented new findings about the BOAT at the High Energy Astrophysics Division meeting of the American Astronomical Society in Waikoloa, Hawaii. Papers describing the results presented—including one describing Swift’s initial detection—will appear in a focus issue of The Astrophysical Journal Letters.
The signal from GRB 221009A had been traveling for about 1.9 billion years before it reached Earth, making it among the closest known “long” GRBs, whose initial, or prompt, emission lasts more than two seconds. Astronomers think these bursts represent the birth cry of a black hole that formed when the core of a massive star collapsed under its own weight. As it quickly ingests the surrounding matter, the black hole blasts out jets in opposite directions containing particles accelerated to near the speed of light. These jets pierce through the star, emitting X-rays and gamma rays as they stream into space.
As the jets continue to expand into space, they produce a multiwavelength afterglow that gradually fades away. William’s team found that the afterglow was more than 10 times brighter than that of any previous gamma-ray bursts observed by Swift.
In many cases, the exploding star also propels debris and other matter into space in a supernova, which should be detectable on Earth a few weeks after the initial GRB. There has been some debate amongst astronomers as to whether this supernova occurred, or if the star instead collapsed straight into the black hole without exploding. One reason the supernova has been challenging to detect is because the GRB occurred just a few degrees above the plane of our own galaxy, where thick dust clouds can greatly dim incoming light. However, using the sensitive Pan-STARRS optical ground telescope, the Young Supernova Experiment collaboration was able to spot the supernova.
“Pan-STARRS observations uniquely allowed us to see deeper in the redder part of the optical spectrum, which allowed us to see the supernova,” said V. Ashley Villar, Mercedes Richards Career Development Professor of Astronomy and Astrophysics, co-hire of the Institute for Computational and Data Sciences at Penn State and a member of the Young Supernova Experiment collaboration. “Our team plans to use the James Webb Telescope to further investigate the supernova and search for signatures of heavy element formation.”
The burst also enabled astronomers to probe distant dust clouds in our own galaxy. As the prompt X-rays traveled toward us, some of them reflected off of dust layers, creating extended “light echoes” of the initial blast in the form of X-ray rings expanding from the burst’s location. Swift’s X-ray telescope discovered the presence of a series of echoes. Detailed follow-up by the European Space Agency’s XMM-Newton telescope, together with Swift data, revealed these extraordinary rings were produced by 21 distinct dust clouds.
“How dust clouds scatter X-rays depends on their distances, the sizes of the dust grains, and the X-ray energies,” explained Sergio Campana, research director at Brera Observatory and the National Institute of Astrophysics in Merate, Italy. “We were able to use the rings to reconstruct part of the burst’s prompt X-ray emission, and also to determine where in our galaxy the dust clouds are located.”
GRB 221009A is only the seventh gamma-ray burst to display X-ray rings, and it triples the number previously seen around one. The echoes came from dust located between 700 and 61,000 light-years away. The most distant echoes—clear on the other side of our Milky Way galaxy—were also 4,600 light-years above the galaxy’s central plane, where the solar system resides.
This extraordinary gamma-ray burst helps provide a deeper understanding of how stars collapse and how black holes are born.
“This once in a lifetime event gave us a unique opportunity to study the death throes of a massive star in incredible detail,” said Jamie Kennea, research professor of astronomy and astrophysics at Penn State who leads the Swift Science Operations Team. “Thankfully, astronomers from around the world answered our call to arms, and the results have been amazing.”
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IGC Alumn Cody Messick wins the Dissertation Award for LIGO Research
Cody Messick, who earned a doctorate in physics from Penn State in 2019, was honored with the Northeastern Association of Graduate Schools’ 2023 Doctoral Dissertation Award. The annual award recognizes one outstanding dissertation that has been produced by a doctoral candidate at one of its member institutions.
“It’s exciting and incredibly validating to receive an award like this,” said Messick, now a postdoctoral researcher at the Massachusetts Institute of Technology. “I set out to write my dissertation from scratch instead of combining papers, because I wanted more control over the way I presented the story of my research. Receiving an award like this makes that effort feel seen, and, while I originally took the route, I did it for myself, and it’s an honor to receive recognition for it.”
Messick’s pioneering research focused on gravitational waves, which are ripples in space that were first hypothesized by Albert Einstein. Messick’s work led to the first-ever discovery in 2015 of gravitational waves using a highly sophisticated measurement device known as the Laser Interferometer Gravitational-Wave Observatory (LIGO), which uses lasers to measure miniscule changes in space occurring from distant astronomy events, such as a supernova. Today, LIGO and similar gravitational-wave detectors are used by an international research team, known as the LIGO-Virgo-KAGRA Collaboration, that is led, in part, by Penn State researchers.
For his doctoral dissertation, “Detecting Gravitational Waves for Multi-Messenger Astronomy,” Messick developed algorithms for sifting through large amounts of data produced by LIGO to identify subtle signals of a distant astronomical event. Messick’s innovations led to the identification of 11 separate gravitational wave signals, as well as the ability to detect signals in real time.
“The most exciting of these detections occurred on Aug. 17, 2017. I was the first person in the world to see that our analysis had identified a signal that went through our detectors within two seconds of an extremely energetic burst of electromagnetic radiation called a gamma-ray burst. We were able to confirm that these two events came from the same astrophysical source: two neutron stars colliding roughly 130 million light-years away,” said Messick. This work was recognized as Science’s Breakthrough of the Year in 2017.
Messick’s work helped to pave the way for LIGO’s data to be an integral part of multi-messenger astronomy, which leverages signals from different sources, such as neutrinos and electromagnetic waves, to create a deeper understanding of the universe.
“Gravitational wave astronomy is now a bona fide field of physics due, in no small measure, to the contributions of Cody Messick while he was a graduate student at Penn State, working on the Laser Interferometer Gravitational-Wave Observatory (LIGO),” said Doug Cowen, professor of physics and astronomy and astrophysics at Penn State. “His analysis techniques were central to the detection and subsequent localization of the first triply-detected gravitational wave, followed very shortly afterward by the first binary neutron star merger discovery, which led directly to the first coincident gravitational wave plus gamma-ray detection. Together, these momentous discoveries have elevated gravitational waves to a preeminent position in the nascent field of multi-messenger astronomy.”
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Miguel Mostafa wins 2023 Faculty Scholar Medal
Miguel Alejandro Mostafá, professor of physics and of astronomy and astrophysics and associate dean for research and innovation in the Eberly College of Science, is one of five Penn State faculty members to receive a 2023 Faculty Scholar Medal for Outstanding Achievement. Established in 1980, the award recognizes scholarly or creative excellence represented by a single contribution or a series of contributions around a coherent theme. A committee of peers reviews nominations and selects candidates.
Nominators said Mostafá has significantly advanced the frontiers of fundamental knowledge regarding particle physics and astrophysics. That’s opened unprecedented windows into the physics of our universe.
Mostafá is an experimental particle astrophysicist who researches the origins of the most energetic particles in the Universe. Mostafá uses cosmic messengers in the form of ultrahigh energy cosmic and gamma rays to probe the physics behind cosmic accelerators. He earned the Faculty Scholar Medal in Physical Sciences.
Mostafá conducts this work through international collaborations at the High Altitude Water Cerenkov Gamma-Ray Observatory (HAWC) in Mexico and the Pierre Auger Observatory in Argentina.
“Rising to prominence as a scientist in large physics collaborations such as HAWC or Auger is not an easy endeavor,” a nominator said. “It requires both keen scientific talent and managerial acumen for complex project management.”
At HAWC, Mostafá’s team oversaw the construction of important components of the observatory. His team also produced various analytical tools that led to the discovery of new gamma-ray sources and the most powerful accelerators in our galaxy.
At Auger, Mostafá steered the hardware design and construction and also had a hand in software, analysis and interpretation. Nominators said his background in physics and astrophysics meant he could be the bridge to cross historical boundaries between particle physics and high-energy astrophysics.
At Penn State, Mostafá helped create the Astrophysical Multimessenger Observatory Network (AMON) by serving as principal investigator for the first NSF-funded grant — which was subsequently renewed — on multi-messenger astrophysics. Mostafá oversees several areas of AMON, including oversight of technology solutions, organizing workshops and international partnerships.
“AMON placed Penn State on the international map in this field by pioneering searches that combine signals from various cosmic sources,” a nominator said. “In the past few years, AMON has made major discoveries by combining observations from various observatories. That led to the landmark observation of a ‘flaring blazar’ in coincidence with high energy neutrinos. That discovery was a direct result of Mostafá’s leadership.”
Mostafá is now working on the Giant Radio Array for Neutrino Detection, which nominators say will lead to new discoveries related to multi-messenger astrophysics.
“Mostafá has all the characteristics that embody a true ‘faculty scholar,’” a nominator said. “He is a scientific leader, an inspiring teacher and mentor, and a citizen-scientist contributing energetically to the academic enterprise and to the scientific awareness in broader society.”
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Sarah Gallagher honored with Outstanding Science Alumni Award
Gallagher is the director of the Interdisciplinary Research Institute for Earth and Space Exploration and a professor of physics and astronomy at Western University in London, Canada. Her astrophysics research focuses on the powerful light-driven winds that emanate from supermassive black holes. She uses both ground and space-based observatories that span the electromagnetic spectrum to reveal the mechanisms that link the growth of the black hole found in the center of every massive galaxy to the galaxy itself. She is engaged in planning and advocating for next generation observatories to enable an ambitious science program to use time domain astrophysics—exploring how cosmic objects change over time, especially on relative short time scales—to map black holes’ inner regions.
As the first science advisor to the president of the Canadian Space Agency, Gallagher advised the agency’s Executive Committee on issues related to science investments and capacity development. She served as a liaison to the academic space science community and other government departments via the Departmental Science Advisor Network of Canada’s Chief Science Advisor. During her two terms, she advised on Open Science policies and co-founded Can COVID, the pan-Canadian pandemic research network. She teaches physics and astronomy and regularly communicates to the public about the value of space science and exploration.
Sarah obtained her Ph.D. with IGC faculty member Niel Brandt, working on X-ray observations of quasar absorption lines
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5th IGC Neighborhood Workshop held in State College
The 5th Annual IGC Neighborhood Workshop, an event for physicists in the local region around Penn State, was held downtown and in the Alumni Center. Faculty, postdocs and grad students, many from Penn State, gave brief talks and interacted with other groups in the immediate vicinity (A ~three hour drive) of State College. Participants included physicists from: Carnegie Mellon University Case Western Reserve University CMU Cornell University Johns Hopkins University Lehigh University Penn State University Space Telescope Science Institute Syracuse University University at Buffalo University of Pennsylvania University of Pittsburgh West Virginia University Thank you to everyone who came out!
IGC Art Exhibition Showcases Institute's Artists
IGC members met in 321 Whitmore to showcase their works, from posters, to instruments and interactive displays. Special thanks is given to Monica Rincon Ramirez for helping to organize. An art booklet will be printed soon, and thanks again to everyone who brought their art to show off!
IGC grad Rachael Huxford writes about the “I am STEM” winners
IGC grad student Rachael Huxford, a science communication intern for the Eberly College of Science, conducted an interview with two ‘I AM STEM’ winners. The I AM STEM speaking contest was designed to help Penn State’s Eberly College of Science students develop and share stories of their science journey. Winners of the contest have been keynote speakers at the college’s annual ENVISION: STEM Career Day Supporting Young Women event where they have been able to inspire other burgeoning STEM minds. Other contest objectives include developing science communication abilities and identifying and showcasing Eberly College of Science students with inspiring, authentic STEM stories. Additional fall 2022 participants included Eberly College of Science undergraduate students Basma AlMahmood, Ariella Biney, and Emma Khoury, and the IGC’s own graduate student Unnati Akhouri.
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Abhay Ashtekar Invited to Write the Foreword for the 50th Anniversary Edition of the Hawking-Ellis Monograph
In 1974, Cambridge University Press published the celebrated monograph Large Scale Structure of Space-time which was immediately hailed as “a masterpiece, written by sure hands” in the book review section of Science. For its 50th anniversary edition, CUP invited Abhay to write a Foreword to put this work in the context of the subsequent developments over the last 5 decades. See the PDF file Of the Foreword:
Discovery of Massive Early Galaxies Defies Prior Understanding of the Universe
Six massive galaxies discovered in the early universe are upending what scientists previously understood about the origins of galaxies in the universe.
“These objects are way more massive than anyone expected,” said Joel Leja, assistant professor of astronomy and astrophysics at Penn State, who modeled light from these galaxies. “We expected only to find tiny, young, baby galaxies at this point in time, but we’ve discovered galaxies as mature as our own in what was previously understood to be the dawn of the universe.”
Using the first dataset released from NASA’s James Webb Space Telescope, the international team of scientists discovered objects as mature as the Milky Way when the universe was only 3% of its current age, about 500-700 million years after the Big Bang. The telescope is equipped with infrared-sensing instruments capable of detecting light that was emitted by the most ancient stars and galaxies. Essentially, the telescope allows scientists to see back in time roughly 13.5 billion years, near the beginning of the universe as we know it, Leja explained.
“This is our first glimpse back this far, so it’s important that we keep an open mind about what we are seeing,” Leja said. “While the data indicates they are likely galaxies, I think there is a real possibility that a few of these objects turn out to be obscured supermassive black holes. Regardless, the amount of mass we discovered means that the known mass in stars at this period of our universe is up to 100 times greater than we had previously thought. Even if we cut the sample in half, this is still an astounding change.
In a paper published today (Feb. 22) in Nature, the researchers show evidence that the six galaxies are far more massive than anyone expected and call into question what scientists previously understood about galaxy formation at the very beginning of the universe.
“The revelation that massive galaxy formation began extremely early in the history of the universe upends what many of us had thought was settled science,” said Leja. “We’ve been informally calling these objects ‘universe breakers’ — and they have been living up to their name so far.”
Leja explained that the galaxies the team discovered are so massive that they are in tension with 99% of models for cosmology. Accounting for such a high amount of mass would require either altering the models for cosmology or revising the scientific understanding of galaxy formation in the early universe — that galaxies started as small clouds of stars and dust that gradually grew larger over time. Either scenario requires a fundamental shift in our understanding of how the universe came to be, he added.
“We looked into the very early universe for the first time and had no idea what we were going to find,” Leja said. “It turns out we found something so unexpected it actually creates problems for science. It calls the whole picture of early galaxy formation into question.”
On July 12, NASA released the first full-color images and spectroscopic data from the James Webb Space Telescope. The largest infrared telescope in space, Webb was designed to see the genesis of the cosmos, its high resolution allowing it to view objects too old, distant or faint for the Hubble Space Telescope.
“When we got the data, everyone just started diving in and these massive things popped out really fast,” Leja said. “We started doing the modeling and tried to figure out what they were, because they were so big and bright. My first thought was we had made a mistake and we would just find it and move on with our lives. But we have yet to find that mistake, despite a lot of trying.”
Leja explained that one way to confirm the team’s findings and alleviate any remaining concerns would be to take a spectrum image of the massive galaxies. That would provide the team data on the true distances, and also the gasses and other elements that made up the galaxies. The team could then use the data to model a clearer picture of what the galaxies looked like, and how massive they truly were.
“A spectrum will immediately tell us whether or not these things are real,” Leja said. “It will show us how big they are, how far away they are. What’s funny is we have all these things we hope to learn from James Webb and this was nowhere near the top of the list. We’ve found something we never thought to ask the universe — and it happened way faster than I thought, but here we are.”
The other co-authors on the paper are Elijah Mathews and Bingjie Wang of Penn State, Ivo Labbe of the Swinburne University of Technology, Pieter van Dokkum of Yale University, Erica Nelson of the University of Colorado, Rachel Bezanson of the University of Pittsburgh, Katherine A. Suess of the University of California and Stanford University, Gabriel Brammer of the University of Copenhagen, Katherine Whitaker of the University of Massachusetts and the University of Copenhagen, and Mauro Stefanon of the Universitat de Valencia.
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Abhay Ashtekar was named Atherton Professor
Congratulations to Dr. Abhay Ashtekar, who has been named Atherton Professor. This position recognizes Emeritus Evan Pugh Professors for their exceptional record in the scholarship of research, teaching, and service over the course of their careers.
Three Penn State researchers awarded scientific grants from Kaufman Foundation
The Charles E. Kaufman Foundation—a supporting organization of The Pittsburgh Foundation, which works to improve the quality of life in the Pittsburgh region—has selected three researchers from the Eberly College of Science to receive research grants this year. The foundation awards grants to scientists at institutes of higher learning in Pennsylvania who are pursuing research that explores essential questions in biology, physics, and chemistry, or that crosses disciplinary boundaries.
Ashley Villar, assistant professor of astronomy and astrophysics and co-hire of the Institute for Computational and Data Sciences at Penn State, was selected to receive a New Investigator grant for her project titled “Unveiling the Final Days of Stellar Life Through Exotic Explosions.” New Investigator grants empower scientists at the beginning of their careers who seek to make a mark in their fields and address core principles in biology, physics, and chemistry or across the disciplinary boundaries of these field.
Villar will study a rare type of supernova—the explosive death of a star—called a Type IIn supernova. Prior to these rare supernovae, the star produces a “death throe” for months to years before its ultimate explosion, ejecting a considerable amount of material that then surrounds the star and that becomes shock heated during the supernova. Villar will combine techniques from high energy physics, machine learning, and statistics to analyze these events and improve our understanding of why only some stars experience this phenomenon.
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David Radice and Stephanie Wissel receive 2022 Climate and Diversity Awards
The Eberly College of Science Climate and Diversity Committee has selected three individuals and one group to receive 2022 Climate and Diversity Awards in recognition of their extraordinary commitment to enhancing the environment of mutual respect and diversity in the college over the past year. The award is supported by the Santacroce Family Climate and Diversity Fund in the Eberly College of Science. The awardees and nominees were honored at an annual ceremony on Thursday, January 16, 2023, to recognize their efforts to make our college community supportive and welcoming to everyone.
The CalBridge program— initiated at Cal Poly Pomona—aims to increase the diversity of physics practitioners by identifying and assisting members of groups historically underrepresented in physics, including by connecting students with Ph.D. programs. With guidance from the Physics Department’s CalBridge program leadership committee, Penn State is one of a handful of universities outside of California to welcome CalBridge participants to its graduate program. The leadership committee includes Stephanie Wissel, Downsbrough Early Career Assistant Professor of Physics and of Astronomy and Astrophysics; Nathan Keim, associate research professor of physics; and David Radice, assistant professor of physics and of astronomy and astrophysics. The committee prepares recruiting materials for the program, tracks applicants through the admissions process, and provides feedback about all applicants at the end of the process. It also helps to support these students’ progress once they are at Penn State.
“This feedback is important to the program and future students in making sure that they understand what we are looking for in applicants, but it has also generated important discussions with the admissions committee about how to equitably evaluate applications,” said a nominator. “After just two years with the program, it has already become a major part of our efforts to diversify the Physics Department’s graduate program.”
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