After reanalyzing the data collected on gravitational waves by the LIGO and Virgo collaborations, an international team of astrophysics was able to detect a dozen previously undetected black hole mergers that were beyond the detection threshold of the original analysis. These mergers could indicate fundamentally new exotic astrophysical scenarios that can only be studied with the aid of gravitational wave astronomy at the moment. A report on this is scheduled for April. conferences American Physical Society website physics.org.
Over the past seven years, 90 events have been identified that cause gravitational waves – disturbances in the fabric of space-time caused by catastrophic-scale phenomena such as mergers of double black holes and neutron stars. “Thanks to gravitational waves, we’re starting to see a wide variety of black holes merging over the last few billion years,” says physicist Seth Olsen of Princeton University, who led the new research. In his opinion, every such observation adds to the knowledge of how black holes form and evolve, but the key to recognizing these signals is finding new effective ways to separate the events from noise, which has intrigued physicists.
To find a dozen additional events, Olsen and colleagues analyzed the data using what’s known as the IAS pipeline, a technique developed by astrophysicist Mathias Zaldarriaga at the Institute for Advanced Study. Zaldarriaga and his team had previously used the IAS pipeline to analyze initial data from the LIGO and Virgo facilities, and were similarly able to detect additional black hole mergers that were missed in the initial analysis. The method includes advanced data analysis and numerical methods for enhanced signal processing with increased computational efficiency compared to the original LIGO and Virgo pipelines. Additionally, it uses statistical techniques that sacrifice some sensitivities to sources that are visible when the data is first processed. But at the same time, they turned out to be particularly sensitive to new sources that the previous approach was more likely to miss – these are, for example, rapidly spinning black holes.