Q&A with the Penn State LIGO Group
Chad Hanna, associate professor of physics and of astronomy and astrophysics; B.S. Sathyaprakash, Elsbach Professor of Physics and Professor of Astronomy and Astrophysics; and graduate students Rebecca Ewing, Rachael Huxford and Divya Singh discuss discoveries made in the third LIGO-Virgo run that increased the number of observed binary coalescences from 11 to 50.
Roger Penrose was awarded half of the 2021 Nobel Prize in Physics.
Roger has been a visiting member of IGC since it was founded and also serves on its External Scientific Advisory Board. From 1993 to 2012, he also held the Francis R. and Helen M. Pentz Visiting Professor of Physics and Mathematics at Penn State. Through regular visits during the first 15 years of this period, he enriched our intellectual lives tremendously through countless discussions (that often ran late into dinner times(!)), seminars and popular lectures.
Shifu Zhu, a graduate student in the Department of Astronomy & Astrophysics, had his research discoveries on radio-loud quasars featured in a 2020 October press release by the Chandra X-ray Center.
Specifically, Shifu analyzed X-ray, optical, and radio data for a large sample of 729 radio-loud quasars, with powerful radio-emitting jets, to determine the nature of their nuclear X-ray emission. His data indicated, surprisingly, that most of their X-ray emission generally does not originate from the jets themselves, but rather comes from a coronal structure lying above the accretion disk. These results challenge 35 years of thinking about the basic nature of this X-ray emission, and they provide insights into the accretion and ejection physics of these systems.
Celebrating Sir Roger’s Nobel Prize in Physics
Roger Penrose is a founding (visiting) member of IGC since 1993 and has served on its Scientific Advisory Board since 2009. He held the Francis R. and Helen M. Pentz Distinguished Professorship in Physics and Mathematics at Penn State from 1993 to 2012. On 12th October 2020, IGC celebrated his 2020 Nobel prize in Physics for “the discovery that black hole formation is a robust prediction of the general theory of relativity” through a special event. B. Sathyaprakash and Don Schneider explained the Theoretical and Observational background behind the discoveries that led to the Nobel Prize. Abhay Ashtekar and Nitin Smarath spoke on Roger’s dazzling contributions to Physics, Mathematics and on how his regular visits enriched the Penn State Community. 140-150 Colleagues and friends joined the event from all over the world.
Nature published a special collection of articles on Multi-Messenger Astrophysics.
It contains a review by Peter Meszaros, Derek Fox, Chad Hanna and Kohta Murase
On May 21, 2019 the Advanced LIGO detectors at Hanford and Livingston in the USA and the Virgo detector in Italy, observed a gravitational wave signal from the heaviest merger of black holes, yet observed.
The merging black holes being roughly 85 and 66 times as heavy as our sun, are among the heaviest ones seen yet. The LIGO group at PSU played a significant role in the observation of this very short and difficult to detect signal which lasted for about one tenth of a second. The remnant produced by the merger is as heavy as about 142 times the mass of our sun which places it in the category of intermediate-mass black holes, an elusive type of heavy black holes that had not been observed directly so far. Being heavier than the black holes observed which have masses comparable to our sun, but less heavy than the supermassive black holes that occupy the centres of galaxies, these intermediate-mass black holes and their formation methods are not well understood by astrophysicists. In fact this discovery is also unusual because it questions existing astrophysical models of black hole formation and stands to open new doors in our understanding of these objects.
When A Supernova Fails...
Nuclear burning and gravity plays together to power most of the energetic events that we see in the universe. Slow and steady nuclear burning produces the light in most of the stars in the sky (including our Sun) that goes on for billions of years. When burning gets vigorous, life goes faster and gets more exciting. Read Rahul Kashyap’s account of the exciting work by IGC researchers.
IGC celebrated its silver jubilee through an international conference igc@25
The multimessenger universe which was held at Penn State from June 23rd to 27th 2019. The scientific program has a dual goal: to assess the current status of our field in broad terms and to discuss future directions. The plenary talks by leading experts provided a broad overview of the field, with emphasis on developments that have occurred in the past ~25 years, while panels focused on developments over the past decade and, especially, the vision for the next decade or two. The after dinner speech, entitled “Multimessenger Astronomy and the Big Questions of the Cosmos: A Billion Light year View”, was given by the NSF Director Dr. France Cordova.
Abhay Ashtekar, Brajesh Gupt, Donghui Jeong and V. Sreenath published an article `Alleviating the tension in the cosmic microwave background using Planck scale physics'
Physical Review Letters, 125, 051302 (2020) was highlighted in many news outlets. It is in the Top 5% of all research outputs scored by Altmetric.
In an invited comment, Miguel Mostafa describes the Astrophysical Multimessenger Observatory Network (AMON)
Amon is an online network that enables real-time coincidence searches using data from the leading multimessenger observatories and astronomical facilities. The Astrophysical Multi-messenger Observatory Network. Nature Reviews; June 23rd, 2020.
Garrett Wendel, Luis Martínez, and Martin Bojowald discuss the fundamental nature of time in our universe.
They describe time from a novel perspective by modeling time as a universal quantum oscillator. The article, Physical Implications of a Fundamental Period of Time, was published in Physical Review Letters, 124, 241301 (2020); on 19th June 2020. It was highlighted in Physics by Katherine Wright, a Senior Editor.
Raising awareness of racism in STEM
In support and solidarity with the Black community and [#Strike4BlackLives](https://twitter.com/hashtag/strikeforblacklives), and to commit to eradicating systemic racism and discrimination especially in academia and science, IGC organized a Zoom meeting on Wednesday, June10th 2020. We had some 137 participants, also from the Physics and Astronomy & Astrophysics Departments and MERSEC at Penn State, and a few from other institutions. The discussion was led by Dr. Stephon Alexander, Professor of Physics at Brown University, who is the current President of the National Association for Black Physicists. Stephon has had close associations with IGC from the time he began his faculty career at Penn State 15 years ago. While we had benefited by reading thoughtful articles and dialogs on the subject prior to the meeting, Stephon's comments, questions and suggestions provided direct insight into the issues that are central to the thinking of leadership in the Black academic community. IGC will continue the dialog both among ourselves and also with the members of this community for ongoing improvement. Thank you, Stephon!
The Story of Loop Quantum Gravity
From the Big Bounce to Black Holes: What happens at the centre black holes? What happened before the big bang? A quantum theory of gravity is needed to answer these questions . Many of the leading scientists who developed Loop Quantum Gravity, one of the most promising attempts, tell the story of how it was developed in this film. We also go on to explore how the theory may be tested via observations of black holes or probing the very early universe. The film tackles some of the biggest questions of existence.
LIGO-Virgo finds mystery object in mass gap
On August 14, 2019, the two Advanced LIGO detectors in the US, at Hanford, Washington and Livingston, Louisiana, and the Advanced Virgo detector in Cascina, Italy, observed a gravitational wave signal produced by the inspiral and merger of two compact objects - one, a black hole, and the other of undetermined nature. The mass measured for the lighter compact object makes it either the lightest black hole or the heaviest neutron star ever discovered in a system of two compact objects, but we can’t be sure which it is. This is also the most asymmetric system observed in gravitational waves as of now. This event was detected in real time by the GstLAL inspiral pipeline which is developed and operated largely by the LIGO group at Penn State.
Cambridge University Press has released a paperback edition of `General Relativity and Gravitation: A Centennial Perspective'.
This volume was commissioned by the International Society on General Relativity and Gravitation and is edited by A.Ashtekar(Editor in Chief), Beverly Berger, James Isenberg and Malcolm MacCallum. It contains 12 Chapters written by leading international experts that provide overviews of the spectacular advances that have occurred in the field over the past three decades or so. The material is divided into 4 parts: I. Einstein's Triumph; II. Was Einstein right? A Centenary Assessment; III. Gravity is Geometry, Afterall; and IV. Beyond Einstein, each with a detailed general introduction written by the Editors. This volume should be an excellent resource both for graduate students as well as experienced researchers in cosmology, general relativity, gravitational waves, and quantum aspects of gravity.
Physics graduate student Rachael Huxford coordinates hundreds of local mask makers
Including more than 50 members of the Penn State community, Rachael is helping to provide cloth masks to small businesses and families in Centre County during the COVID-19 pandemic.
LIGO detects another probable Neutron Star collision
Gravitational waves detected on April 25, 2019, by the LIGO Livingston Observatory were likely produced by a collision of two neutron stars, according to a new study by an international team including Penn State researchers. IGC members Patrick Godwin, Ryan Magee, B. Sathyaprakash and Surabhi Suchdev explain why this discovery is so exciting. This detection was made possible by the GSTLAL online software developed by faculty and postdocs at the Institute for Gravitation and the Cosmos. The total mass of the binary is significantly larger than all such systems we know in our galaxy and challenging astrophysical models of the formation of binary black holes.
The Future of Gravitational Wave Astronomy
YouTube video by Phil and Monica Harper, on the Multimessenger Universe featuring interviews with leading figures in the field. It was filmed during the conference IGC@25: The Multimessenger Universe that celebrated the Silver Jubilee of the Institute for Gravitation and the Cosmos.
Penn State's Bianchi, Gupta and Sathyaprakash were coauthors of a paper that was awarded second prize of the annual Buchalter Cosmology prize announced at the AAS meeting in Hawaii in early January.
The prize recognizes their work on the possible origin of LIGO's black holes in the very early Universe, offering quantum origin of their small spins.
IGC’s Rachael Huxford was co-author of one of the most-read publications in The Physics Teacher of the American Association of Physics Teachers.
The paper describes a demonstration on classroom simulation of gravitational waves from orbiting binaries. Popular demonstrations commonly use stretched spandex fabric to illustrate the way in which curved spacetime mimics the force of gravity in general relativity. In this spirt, Huxford and co-authors used a similar mode to illustrate gravitational waves from orbiting binaries, whose discovery was recognized with the 2017 Nobel Prize in Physics. They developed a simple and inexpensive demonstration which produces the pattern of outgoing spiral ripples that has entered the public imagination through images from numerical simulations.
Eberly College of Science 2020 Frontiers of Science Lecture Series entitled `Predicting the Future Improving Lives and Communities through Modeling'
The series will consist of 6 public lectures, held on consecutive Saturdays in 101 Thomas Building at the University Park Campus.
Emily Rolfe Grosholz, Edwin Earle Sparks Professor and member of the Institute for Gravitation and the Cosmos, will offer a poetry reading on Thursday, January 30 at 7:30 PM in the Paterno Library's Foster Auditorium.
Dr. Grosholz's most recent collections <i>The Stars of Earth: New and Selected Poems</i>(2017) and <i>Great Circles: The Transits of Mathematics and Poetry</i> (2018) showcase her larger interests in the intersections between philosophy, mathematics, science and language.