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GAPP - Gravity, Astrophysics and Particle Physics

GAPP - Gravity, Astrophysics and Particle Physics

320 Whitmore Lab

2025-09-12

Abstract: The 14th of September marks the 10th anniversary of one of the most important scientific breakthroughs of the 21st century: the detection of GW150914. This not only provided direct evidence for the existence of black holes in our universe but also vindicated the existence of gravitational waves predicted by Einstein in 1916, and the cutting edge engineering and science of the LIGO detectors. This marked the birth of a new era of astronomy. Detecting gravitational waves is challenging, since the data we analyze is dominated by noise. Yet over the past decade, we have identified over 370 events (preliminary value) by the LIGO/Virgo/KAGRA gravitational wave detector network. The continued improvement in the capability of the detectors and data analysis methods have enabled the latest observing run, O4, with over 280 new events (preliminary value). Detections, including near-real time searches of gravitational waves, have been led by the PSU LIGO group. In this talk, we present to you two outliers in the catalog of the detected events: GW231123 and GW250114. GW231123 is the most massive event observed to date, marking a departure from the stellar mass systems into an intermediate mass regime. Arriving from around the direction of the Leo constellation, GW250114 is a powerful cousin of GW150914. Captured by the two U.S. detectors with a signal-to-noise ratio of 76—roughly 3 times stronger than GW150914—GW250114 enabled measurements of black hole parameters with 300% greater precision. This unprecedented accuracy has, for the first time, put Stephen Hawking’s celebrated area theorem to the test beyond doubt, showing that the surface area of black holes never decreases in classical processes, with a failure rate of only a few parts in a million. These events sit at the pinnacle of scientific and technological advancement in the field of astronomy, providing us not only with an opportunity to uncover the deepest workings of the universe, but also signals the dawn of a new era in precision gravitational-wave astronomy.

TimeSpeakerTitle
10:00Shio Sakon and Vaishak PrasadExceptional gravitational wave events from the fourth observing run of LIGO/Virgo/KAGRA: GW231123 and GW250114
About our wordmark
Monica The IGC wordmark was created by Monica Rincon Ramirez, while she was a graduate student at the Institute for Gravitation and the Cosmos (IGC). Monica enjoys drawing new connections between fundamental theory and observations. Her graduate work includes specialized topics in general relativity, loop quantum gravity, and quantum fields in cosmological backgrounds. In particular, her thesis work focused on finding effective quantum corrections to gravitational phenomena from spinfoams, and applications to cosmology. She received her PhD in 2024.

The wordmark symbolizes the scope and variety of research at the IGC. The base of the image represents quantum gravity, evoking the quantum geometrical picture from spinfoams and loop quantum gravity. These are among the approaches to fundamental questions studied at the Center for Fundamental Theory. The middle of the image represents the Center for Theoretical and Observational Cosmology by galaxies embedded in a smooth surface, characteristic of spacetime in general relativity and the much larger physical scales studied in cosmology. Finally, at the top, the surface curves to an extreme, representing a supermassive black hole accompanied by an energetic jet. These elements depict an active galactic nucleus, inspired by Centaurus A. Just to the right, a pair of black holes approaches merger. This top portion of the wordmark represents the Center for Multimessenger Astrophysics, which specializes in the study of high-energy phenomena in the universe.