Improving theoretical predictions for gravitational-wave astronomy

Otto Hahn Medal for Mohammed Khalil

June 12, 2024

Mohammed Khalil, a former PhD student at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in the Potsdam Science Park, has been awarded the Otto Hahn Medal for his outstanding doctoral thesis. Khalil, who is now a postdoctoral researcher at the Perimeter Institute for Theoretical Physics in Canada, received the award for his significant contributions to making theoretical waveform templates precise enough for gravitational-wave astronomy. Khalil received the medal and a prize of 7500 euros today during the Annual Meeting of the Max Planck Society in Berlin.

The era of gravitational-wave astronomy began on September 14, 2015, with the first detection of gravitational waves from a binary black hole merger by the LIGO-Virgo Collaboration. Since this landmark discovery, gravitational-wave signals have been detected from the mergers of about 90 binary systems, with more than 100 potential signals under investigation. These detections complement electromagnetic observations and tell us about binary black holes and neutron stars, their properties, and their origins. Gravitational waves also probe gravity in the strong-field regime, allowing the search for deviations from general relativity.

But how do you find the tiny spacetime distortions in the detector data? The successful search for gravitational waves requires detailed knowledge of the expected signals, so researchers are developing sophisticated methods to solve Einstein's equations and predict highly accurate template waveforms. These waveform models enable the detection of the signals and, additionally, to determine the physical properties of the gravitational-wave sources.

“The focus of my dissertation was to improve the mathematical description of how black holes and neutron stars orbit each other and eventually merge. This is important for producing accurate waveform models that we use to search for gravitational-wave signals, to understand their origin, and to test the theory of gravity,” explains Mohammed Khalil. During his PhD, he laid the foundation for the most accurate waveform models to date, including effects caused by the rotation of the individual black holes. He helped to develop one (of the only two existing) more accurate waveform models that researchers use to measure via gravitational-wave observations how elliptic the orbits of the merging objects were. He also developed, for the first time, a complete model of effects that cannot be explained by simple approximations and that occur in theories beyond Einstein's theory of gravity.

The awardee

Mohammed Khalil (born 1992) received his PhD in 2022 from the University of Maryland. He received the award for his thesis entitled “Analytical modeling of compact binaries in general relativity and modified gravity theories” which he completed at the Max Planck Institute for Gravitational Physics in Potsdam, in the Astrophysical and Cosmological Relativity department of Alessandra Buonanno. In 2021, the physics department of the University of Maryland honored Khalil's research with the Charles W. Misner Award. Currently, Khalil is a postdoctoral researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

Recognition for excellent junior scientists

The Max Planck Society has honored up to 30 young scientists and researchers each year with the Otto Hahn Medal for outstanding scientific achievements since 1978. The award comes with a monetary sum of 7500 euros as recognition. The prize is intended to motivate especially gifted early career researchers to pursue a future university or research career.

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