Colliding Neutron Stars
Unleash Gravitational Waves

CSUF News Service

 

Oct. 16, 2017

Cal State Fullerton astrophysicist Jocelyn Read has spent more than a decade investigating what a gravitational wave signal from a cosmic collision of neutron stars would reveal.

The signal came in loud and clear on Aug. 17, 2017, at 8:41 a.m. Eastern Daylight Time, from a galaxy 130 million light years away from Earth. A pair of orbiting neutron stars had crashed together, sending gravitational-wave signals to the two Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors in the United States and the European Virgo detector.

"It was an incredibly rich signal, with the signal from the detectors lasting more than 30 seconds, slowly chirping from a low thrum to a high final whoop!" relayed Read, whose astrophysical research helped interpret the gravitational-wave signal.

This first-ever discovery of gravitational waves from a cataclysmic merger of a binary neutron star system was published today in Physical Review Letters, announced the international LIGO Scientific Collaboration and the Virgo collaboration. The Advanced LIGO Observatory in Hanford, Washington, and Livingston, Louisiana, and the Virgo detector, near Pisa, Italy, made the three-detector observation.

 

Read is a leading binary neutron star astrophysics expert and a lead writer of the journal paper. She also has leadership roles with LIGO and Virgo to interpret the analysis of gravitational waves from this new astronomical source.

As an expert of extreme stellar objects, Read's research in astrophysics has focused on observing gravitational waves from neutron stars to better understand their structure and composition. Her work with LIGO and Virgo includes data analysis to determine the masses, spins, sky location and other properties of this gravitational-wave source. She is the senior lead of LIGO Scientific Collaboration's Extreme Matter Group, which is coordinating investigations of neutron star matter by LIGO and Virgo scientists.

"This discovery has ushered in a new era in multi-messenger astronomy, sparking coordinated work by astronomers across the globe, and revealed the dynamics of a neutron star merger," said Read, assistant professor of physics, who joined CSUF's Department of Physics in 2012.

"I’m not only shocked, but also delighted by the clarity of our measurement and this unprecedented collaboration across fields of astronomy."

This marks the first cosmic event observed in both gravitational waves and light. As the neutron stars spiraled together and merge, they stretched and distorted the surrounding space-time, giving off energy in the form of gravitational waves. But unlike black hole mergers, neutron star mergers also produce light. The collision produced a short gamma-ray burst — a brief blast of high energy light, Read explained. The fireball of gamma rays was observed independently by NASA's Fermi space telescope.

"This confirmed a long-held suspicion, developed over 50 years of scientific debate, that these astrophysical mysteries are produced by the collision of neutron stars," she said.

Guided by the LIGO and Virgo detectors working together to locate the gravitational-wave source, astronomers were able to pinpoint a new glowing light in the exact location of the neutron star merger in the galaxy known as NGC 4993.

CSUF Scientists Key in New Discovery

Read's colleagues, CSUF physicists Joshua Smith and Geoffrey Lovelace — all members of the LIGO Scientific Collaboration — along with undergraduates Erick Leon and Isabella Molina, postdoctoral research associate Marissa Walker, computation specialist Joseph Areeda and CSUF alumnus Torrey Cullen, a doctoral student at Louisiana State University, also contributed to this latest scientific finding and are co-authors of the neutron star discovery paper. Read's undergraduate students worked with LIGO and Virgo scientists across the globe to check and confirm the reliability of the data analysis.

"We are so fortunate to have Jocelyn, one of the world’s neutron star experts, at Cal State Fullerton," said Smith, associate professor of physics and Dan Black Director of Gravitational- Wave Physics and Astronomy. "I am extremely proud of the role that she and our students have played in this foundational discovery in astronomy."

The Cal State Fullerton physicists and their students at the Gravitational-Wave Physics and Astronomy Center contributed significantly to the first discovery of gravitational waves in 2015 — a milestone in the fields of physics and astronomy. This detection of gravitational waves from the collision of two black holes in galaxy a billion light years away confirmed Einstein's 1915 general theory of relativity. Over the last five years, the CSUF researchers have garnered more than $4.2 million in external grant funding for their work in gravitational-wave astronomy.

LIGO has since announced three more gravitational wave detections from binary black hole systems, including a Sept. 27 announcement of the first joint detection by both LIGO and Virgo detectors. Smith and Lovelace were instrumental in helping to write the journal paper, published Oct. 6 in Physical Review Letters, modeling the black holes that emitted the waves and checking the quality of the detector data.

Read — and her CSUF colleagues and students — looks forward to more neutron star mergers and other history-making astronomical discoveries.

"Seeing this signal of gravitational waves from neutron stars so early in Advanced LIGO’s observations suggests that the best is yet to come. Like we found for merging black holes, the universe is rich with these gravitational-wave signals," she said. "I can’t wait to see what we’ll be able to learn in the coming years."

About LIGO and Virgo

LIGO is funded by the 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) making significant commitments and contributions to the project. More than 1,200 scientists and some 100 institutions from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration and the Australian collaboration OzGrav. Additional partners are listed online at http://ligo.org/partners.php

The Virgo collaboration consists of more than 280 physicists and engineers belonging to 20 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; eight 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 the University of Valencia; and the European Gravitational Observatory, EGO, the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef.

 

CSUF Media Contacts:

Jocelyn Read
Physics
jread@fullerton.edu   |   657-278-8753

Joshua Smith
Physics
josmith@fullerton.edu   |   657-278-3716

Geoffrey Lovelace
Physics
glovelace@fullerton.edu   |   657-278-7501

Debra Cano Ramos
dcanoramos@fullerton.edu   |   657-278-4027

Chi-Chung Keung
ckeung@fullerton.edu   |   657-278-8487

Paula Selleck
pselleck@fullerton.edu   |   657-278-4856