CSUF News Service
Dec. 3, 2018
Top: A computer calculation showing what two black holes just about to merge would look like up close, created by using data from LIGO’s observation of GW150914 and solving Einstein’s equations of general relativity. Credit: SXS Lensing / Simulating eXtreme Spacetimes project
Above: A visualization of the merging black holes that LIGO and Virgo have observed so far. The video shows numerical-relativity calculations of the black holes’ horizons and the emitted gravitational waves, during the final few orbits of the black holes as they spiral inwards, merge and ring down. Each numerical-relativity calculation is consistent with one of the observations in the LIGO-Virgo catalog. As the horizons of the black holes spiral together and merge, the emitted gravitational waves become louder (larger amplitude) and higher pitched (higher in frequency). This movie is inspired by the Kepler Orrery. Credits: CSUF Teresita Ramirez Aguilar/CSUF Geoffrey Lovelace/SXS Collaboration/LIGO-Virgo Collaboration
LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council-OzGrav) making significant commitments and contributions to the project. More than 1,200 scientists from around the world, including from CSUF, participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. A list of additional partners is available online.
The Virgo collaboration consists of more than 300 physicists and engineers belonging to 28 different European research groups: six from Centre National de la Recherche Scientifique
(CNRS) in France; 11 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in the Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with IFAE and the Universities of Valencia and Barcelona; two in Belgium with the Universities of Liege and Louvain; Jena University in Germany; and the European Gravitational
Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef. A list of the Virgo Collaboration can be found online. More information is available on the Virgo website.
Cal State Fullerton undergraduate physics researcher Teresita Ramirez Aguilar is learning to use supercomputers to create and visualize simulations of colliding black holes that produce gravitational waves — and is making waves of her own. Her research appears in today's (Dec. 3) announcement by LIGO and Virgo of four new gravitational-wave detections from black-hole mergers.
The National Science Foundation-supported LIGO (Laser Interferometer Gravitational-Wave Observatory) and the European-based Virgo gravitational-wave detector have now confidently detected gravitational waves from a total of 10 stellar-mass binary black hole mergers and one merger of neutron stars, which are the dense, spherical remains of stellar explosions, the LIGO Scientific Collaboration announced. Six of the black hole merger events had been reported before, while four, all discovered in 2017, are newly announced.
All of the gravitational-wave events are included in a new catalog, released Dec. 1, with some of the events breaking records. The new event called GW170729 was detected in the second observing run on July 29, 2017, and is the most massive and distant gravitational-wave source ever observed. In this coalescence, which happened roughly 5 billion years ago, an equivalent energy of almost five solar masses was converted into gravitational radiation.
The simulation that Ramirez Aguilar, a junior, created for the announcement, with research adviser Geoffrey Lovelace, associate professor of physics, uses computer calculations to model the gravitational waves LIGO has observed to date, as well as the black holes that emitted the waves. The image shows the horizons, or surfaces, of the black holes above the corresponding gravitational wave.
Lovelace and physics colleagues Joshua Smith and Jocelyn Read — all members of the international LIGO Scientific Collaboration — and their student researchers at CSUF's Gravitational Physics and Astronomy Center (GWPAC) have played significant roles in the detection of gravitational waves since the first gravitational wave discovery was announced by LIGO in 2016.
Beginning in 2015, second-generation LIGO detectors observed gravitational waves for the first time, giving scientists a new sense to observe the universe. The physicists and their students played key roles in discoveries of gravitational waves in 2015, 2016 and 2017. Read, an astrophysicist and associate professor of physics, and her students were part of the first discovery of gravitational waves from neutron stars in 2017.
Smith, professor of physics and Dan Black Director of Gravitational Wave Physics and Astronomy, postdoctoral research associate Marissa Walker, and student researchers are continuing to work on understanding and minimizing the noise in LIGO detectors, which helps to recover the waves from the detector data.
While Read and her students played leading roles in LIGO’s first observation of merging neutron stars, which is the loudest wave in the catalog, their work continues to focus on learning about how neutron star matter behaves.
The ongoing work of Lovelace and his students, including Ramirez Aguilar, focuses on using supercomputer calculations to model the merging black holes that LIGO and Virgo detect.
"These models help us interpret what kinds of black holes emitted the waves LIGO and Virgo observed," Lovelace said.
For the past two years, Ramirez Aguilar has been involved in immersive research with Lovelace, where she is learning how to use computer code to solve the equations of Albert Einstein's general theory of relativity, called the Spectral Einstein Code. She performs the numerical relativity simulations of colliding binary black holes on the GWPAC's National Science Foundation-funded supercomputer.
"This research is so cool because I get to learn about some of the craziest phenomena in our universe," said Ramirez Aguilar, a research scholar in the Louis Stokes Alliances for Minority Participation program at CSUF who plans to pursue a doctorate in physics.
"It's important that we get people interested in science, and creating visualizations like these are important for public outreach. They not only help to ignite interest in gravitational-wave science, but also help give intuition into the kinds of black holes observed, such as their different shapes and sizes."
Since the second observing run ended in August 2017, LIGO — with detectors in Washington and Louisiana — and Virgo have undergone major upgrades to make detectors more sensitive. The next observing run is scheduled to start in spring, and is expected to yield even more cosmic objects and gravitational waves, Lovelace said. For more about the latest National Science Foundation support for CSUF gravitational-wave science, continue reading here.