Researchers advance gravitational wave detection to study collisions of neutron stars and black holes

Researchers at the University of Minnesota-Twin Cities School of Science and Engineering are co-leading a new study with an international team that will improve the detection of gravitational wave ripples in space-time.

The research aims to send an alert to astronomers and astrophysicists within 30 seconds of detection, helping to improve understanding of how neutron stars and black holes, as well as heavy elements including gold and uranium, are created.

The paper titled “Low-latency gravity wave warning product and its performance during the fourth LIGO-Virgo-KAGRA observation run” was recently published in Proceedings of the National Academy of Sciences.

Gravity waves interact with space-time by compressing it in one direction and stretching it in the vertical direction. That’s why the current state-of-the-art gravitational wave detectors are L-shaped and measure the relative lengths of lasers using interferometry, a measurement method that looks at the interference pattern produced by the combination of two light sources.

Detecting gravitational waves requires precise measurements of the length of the laser: equivalent to measuring the distance to the nearest star, about four light-years away, down to the width of a human hair.

The research is part of the LIGO-Virgo-KAGRA (LVK) collaboration, a global network of gravitational wave interferometers.

In the latest simulation campaign, data from previous observation cycles were used and simulated gravitational wave signals were added to show the performance of software and equipment upgrades. The software can detect the shape of the signal, track how it behaves, and estimate what mass is involved in the event, such as a neutron star or a black hole. Neutron stars are the smallest and densest stars known to exist, formed when massive stars explode in supernovae.

Once the software detects a gravitational wave signal, it sends an alert to subscribers (usually an astronomer or astrophysicist) to tell them where the signal is in the sky. With this upgraded observation cycle, scientists are able to send alerts faster, within 30 seconds after detecting gravity waves.

“Through this software, we can detect gravitational waves produced by neutron star collisions, which are usually too faint to see unless we know exactly where to look,” said Andrew Toivonen, Ph.D. )explain. student in the School of Physics and Astronomy at the University of Minnesota, Twin Cities.

“Detecting gravitational waves first will help localize the collision and help astronomers and astrophysicists complete further research.”

Astronomers and astrophysicists can use this information to understand how neutron stars behave, study nuclear reactions between neutron star and black hole collisions, and how heavy elements including gold and uranium are produced.

This is the fourth observation using the Laser Interferometer Gravitational-Wave Observatory (LIGO), which will continue until February 2025. After this observation, researchers will continue to look at the data and make further improvements, with the goal of issuing alerts faster.

Authors of the multi-institution paper include Michael Coughlin, an assistant professor in the University of Minnesota’s School of Physics and Astronomy, and Toivonen.