GAPP - Gravity, Astrophysics and Particle Physics

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.