New Window on the
Cosmos

The time to pop the champagne had finally arrived. Applause, whoops and a serenade of “chirps” erupted inside Cal State Fullerton’s Gravitational-Wave Physics and Astronomy Center on this early February 2016 morning. The first direct detection of gravitational waves — ripples in the fabric of space-time — had just been announced to the world, opening a new window onto the cosmos. An international collaboration of scientists, including researchers from Cal State Fullerton, heard the distinctive “chirp” — a pair of black holes colliding over 1 billion years ago in the distant universe that produced the gravitational waves. The observation of the black-hole merger also confirmed a major prediction Albert Einstein made 100 years ago in his general theory of relativity: gravitational waves exist.

As key contributors in the discovery, Titan researchers and their students gathered inside the gravitational-wave research center in McCarthy Hall to witness the announcement by the National Science Foundation and international Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific Collaboration. After LIGO scientists proclaimed, “We did it!” at the news conference in Washington, D.C., the Titans cheered with their colleagues across the globe.

Leading the CSUF research team is Joshua Smith, associate professor of physics, with Jocelyn Read and Geoffrey Lovelace, both assistant professors of physics, and Alfonso Agnew ’94 (B.A. math, B.S. physics), professor of mathematics. Read and Smith are leaders in the LIGO Scientific Collaboration working groups that searched for and validated the gravitational-wave signal.

The LIGO Scientific Collaboration involves more than 1,000 scientists from universities around the United States and in 14 other countries, including CSUF. Additionally, more than 40 CSUF undergraduates and master’s-level students have worked on this groundbreaking research and shared in the discovery.

Cal State Fullerton’s significant contributions focused on different aspects of LIGO gravitational-wave research. Smith’s work centered on identifying and removing sources of noise in the Advanced LIGO instruments to improve the quality of the data in searching for gravitational waves. Read, an astrophysicist, explored how neutron stars can produce gravitational waves. Lovelace, a computational relativist, created computer simulations and visualizations to better predict the sources of gravitational waves, such as colliding black holes or a black hole tearing apart a neutron star. Agnew has developed mathematical methods to find and study cosmological solutions to Einstein’s equations in the past, and is currently working toward building and studying models of objects that emit the gravitational-wave signals.

Faculty members also have received more than $2 million in funding from the National Science Foundation and the Research Corporation for Science Advancement for their research.

“In all of human existence, people have been mystified by the skies. Nearly everything we’ve learned about astronomy, we’ve learned from light waves,” says Smith, Dan Black Director of the Gravitational-Wave Physics and Astronomy Center. “What I’m most excited about with this first gravitational-wave detection, is it opens up a new field of astronomy, where scientists use gravity to see astronomical objects like black holes, neutron stars and supernova explosions. What we’ll learn will have long-term benefits to society that are impossible to predict.”

Colossal Black-Hole Collision

The violent merging of the two black holes was incredibly powerful, radiating the equivalent of three times the mass of the sun into pure energy, explains Smith. Gravitational waves had been predicted but never observed — until 2:50:45 a.m. Pacific Standard Time Sept. 14, 2015, when the identical LIGO detectors, located in Livingston, Louisiana, and Hanford, Washington, captured the gravitational-wave signal, sending the physicists into a whirlwind of excitement.

“The fact that such a strong signal was observed suggests that the heavens may be brighter with gravitational waves and black-hole collisions than previously expected,” says Smith.

The Titan scientists, together with their colleagues from all over the world, worked around the clock for the next several months to rule out a false signal and confirm the discovery before announcing it to the world.

Alone in her office, Read first heard the “chirp” as the data, sent by a colleague, streamed from her laptop. She exploded with excitement. “It was like recognizing an old friend you never expected to see.”

Lovelace, who simulates colliding black holes on the University’s specially built supercomputer known as the Orange County Relativity Cluster for Astronomy (ORCA), was amazed by the astrophysical observation: “This is the most powerful event in the universe that humans have ever seen. It’s thrilling to see this first glimpse of space and time warping under the most extreme conditions in the universe.”

The scientists also kept the discovery a secret for nearly five months — until Feb. 11, the day of the news conference.

The Discovery Paper

A journal article about the gravitational-wave discovery was published in Physical Review Letters the same day as the news announcement. As members of the LIGO Scientific Collaboration, Smith, Read and Lovelace, along with Joseph Areeda, a computation specialist in the Gravitational-Wave Physics and Astronomy Center, and six physics graduates all are co-authors. Lovelace and his students also contributed simulations of two black holes merging that are featured in the article.

Read also edited the public science summary explaining the discovery, and Smith served as one of the primary editors of the discovery article, along with physicists from Caltech, MIT, Albert Einstein Institute in Germany, University of Paris and University of Rome.

For the last several years, the Titan physicists have served in leadership roles with the LIGO Scientific Collaboration. Smith has chaired the collaboration’s detector characterization group and served on its executive committee. Read currently serves as co-lead of the binary neutron star sub-group and has served as co-chair of the Academic Advisory Committee and an editor of LIGO Magazine. Lovelace serves on the executive committee of the Simulating eXtreme Spacetimes numerical-relativity collaboration, a multi-institutional research effort, which includes Cal State Fullerton.

Catching Future Waves

The discovery was made possible by the enhanced capabilities of Advanced LIGO, which involved a major technological upgrade to the observatories in 2015. Plans are underway for scientific collaboration with India, which is building an advanced gravitational-wave detector.

“Our work to improve the sensitivity of our instruments, better understand the full array of possible gravitational-wave sources, and learn as much as possible from this detection and from future observations will give us lots to do,” says Smith. “Together with our students, and with scientists around the world, we will continue to explore this new frontier of astronomy.”