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RCSA Community Participates in LIGO Discovery

LIGO/NSF Sonoma State University A. Simonnet
LIGO/NSF Sonoma State University A. Simonnet

Members of the RCSA community played important roles in the latest triumph of big science, the detection of gravitational waves generated by a kilonova, the immense release of energy and matter from the collision of two neutron stars traveling near the speed of light. The detection was followed up by the greatest multi-spectrum array of observations in the history of astronomy, answering one of the great scientific questions, how the heaviest elements in the Universe are created.

The possibility of detecting such cosmic events by LIGO and following up detection with rapid response observations across the electromagnetic spectrum was an important topic of discussion at Scialog: Time Domain Astrophysics meetings in 2015 and 2016.

RCSA President Dan Linzer said of the kilonova discovery, “The combined efforts of literally thousands of astrophysicists around the world to generate and analyze these incredibly exciting observations are a testament to the power of science cooperation and collaboration, which (on a smaller scale!) is exactly the goal of RCSA in bringing together scientists through our Scialog and Cottrell Scholars programs.”

Neutron stars are extremely dense – typically only about 12 miles in diameter, but with mass greater than the Sun. So dense that when they collide it’s a major event in the universe, involving titanic forces that blow off immense amounts of energy in the form of gamma rays, X-rays, ultraviolet, infrared, radio waves and visible light.  Matter is created as well – including gold and other heavy elements – and hurled far into space as the combined gravity of these supermassive stars is almost instantly transformed into a black hole.

Such collisions are the engines of creation, giving rise to whole solar systems, including the one we inhabit.

David Reitze, Cottrell Scholar 1996, told The New York Times, “It’s the greatest fireworks show in the universe.” Reitze, of Caltech, is the executive director of the Laser Interferometer Gravitational-Wave Observatory, or LIGO.

LIGO, consisting of two identical detectors, one in Hanford, Washington, and the other in Livingston, Louisiana, detected gravitational waves from the kilonova August 17th. A European-based detector, called VIRGO, helped astrophysicists to locate the collision to an area of the sky roughly 130 million light years from earth. The event was also quickly confirmed by the Gamma-ray Burst Monitor on NASA’s Fermi space telescope.

The gravitational waves were detectable for about 100 seconds, and the signal strength indicated colliding neutron stars were the source. About two seconds after LIGO first noticed these ripples in spacetime, visible light from the collision reached earth, and over the next few days more than 100 earth-based observatories focused on the event, marking the first time scientists have been able to monitor colliding neutron stars, much less in such staggering detail.

Vicky Kalogera, Cottrell Scholar 2004, was one of 10 people who wrote a comprehensive paper in Astrophysical Journal Letters based on the contributions of 3,500 other coauthors studying the data from the collision. That paper almost killed the paper-writing team,” Kalogera told The New York Times.

Numerous Scialog Fellows and Cottrell Scholars are co-authors of the Astrophysical Journal Letter. Several participated in a press conference to explain the history-making nature of the LIGO discovery and astronomical observations at a press conference sponsored by the National Science Foundation on Monday, including:

  Vicky Kalogera, the Daniel Linzer Distinguished University Professor in Physics & Astronomy at Northwestern University;

  Edo Berger, professor of astronomy, Harvard University;

  Alessandra Corsi, assistant professor, Department of Physics and Astronomy, Texas Tech University;

  Ryan Foley, assistant professor of astronomy and astrophysics, University of California-Santa Cruz;

  Andy Howell, staff scientist at Las Cumbres Observatory/UC-Santa Barbara;

  David Sand, assistant professor in astronomy, University of Arizona.

Scialog Fellow Brian Metzger, a theoretical astrophysicist at Columbia University, coined the term “kilonova” in 2010. Cottrell Scholar and Scialog Fellow Duncan Brown, Syracuse University, wrote a section of his 2010 Cottrell Scholar proposal on "Combining the Power of Gravitational-wave and Electromagnetic Astronomy."  In the past two months the vision of these early career scientists and so many others came true.

“Research Corporation for Science Advancement is proud to have so many members of the community of scientists whom we’ve supported contribute to one of the most important astronomical discoveries of the 21st century,” said RCSA Scialog Program Director Richard Wiener.

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