Institute for Gravitation and the Cosmos

2023-02-27

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:

2023-02-23

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.

Abhay Ashtekar was named Atherton Professor

2023-02-14

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.

2023-02-09

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.

2023-02-09

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.”