New campaign to detect gravitational waves

2023-05-30 10:15:31

The LIGO-Virgo-KAGRA (LVK) collaboration has entered a new observation period with improved instruments, new and even more accurate signal models, and more advanced data analysis methods. The LVK collaboration is made up of scientists from around the world who use a network of observatories—LIGO in the United States, Virgo in Europe, and KAGRA in Japan—to search for gravitational waves. These waves are ripples in space-time, generated by the collision of black holes and other extreme cosmic phenomena.

This observing period, labeled O4, promises to take gravitational wave astronomy to the next level. O4 will last 20 months, including up to two months of start-up breaks. It will be the most sensitive search for gravitational waves to date. LIGO has now resumed operations, while Virgo will be incorporated by the end of the year. KAGRA has joined as well, but it will only operate for one month. After some improvements, it will rejoin.

“Thanks to the work of more than 1,000 people around the world over the past few years, we will gain our deepest insight into the gravitational-wave universe to date,” said Jess McIver, deputy spokesperson for the LIGO Scientific Collaboration (LSC). acronym in English). “A longer range means that we will learn more about black holes and neutron stars, and that we will increase the chances that we will find something new. We’re very excited to see what’s out there.”

The Institute for Space Studies of Catalonia (IEEC) participates in this collaboration through the Institute of Cosmic Sciences (ICC) of the University of Barcelona (UB), which has researchers working on Virgo. This detector will continue commissioning activities to increase its sensitivity before joining O4 later this year. “Over the past few months, we have identified several sources of noise and made significant progress in sensitivity, but have not met the design target,” said newly elected Virgo spokesperson Gianluca Gemme. “We are convinced that achieving the highest sensitivity of the detector is the best way to maximize its discovery potential.”

Rendering of two black holes shortly before colliding and merging into one, a process that generates detectable gravitational waves. (Image: NASA’s Goddard Space Flight Center)

KAGRA is already working with the sensitivity planned for early O4.

With the increased sensitivity of the detectors, O4 will observe a larger fraction of the universe than in previous observing periods. It is estimated that the LIGO detectors, thanks to their increased sensitivity, will be able to make many more detections of mergers of black holes or other objects. Also, the increased sensitivity will increase the ability to extract more physical information from the data. This higher signal fidelity will improve scientists’ ability to test Einstein’s theory of General Relativity and infer the true population of dead stars in the local universe.

The first gravitational wave signals were detected in 2015. To date, the global network has detected more than 80 black hole mergers, two probable neutron star mergers, and some events that were very likely black holes merging with neutron stars. During O4, researchers hope to observe even more energetic cosmic phenomena and gain greater insight into the nature of the universe. (Source: IEEC / UB / ICCUB / LIGO-Virgo-KAGRA Collaboration)