On Aug. 17, 2017, at 5:41 a.m. Pacific Time, those waves arrived at Earth and were picked up by three intricate, kilometers-long gravitational wave detectors, one of which is in Washington state. This gravitational wave signal briefly preceded a faint light signal from the same event, which was picked up by several Earth- and space-based astronomical observatories. This scientific feat by the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO) and Europe-based Virgo detector, along with partners at approximately 70 observatories.

“Today’s announcement marks the first time that we have detected gravitational waves from the merger of two neutron stars,” said , assistant professor of physics at the 91Ě˝»¨ Bothell. “In addition, this is the first time that other observatories detected electromagnetic waves emanating from the astronomical event that generated these gravitational waves.”

Key is one of three 91Ě˝»¨faculty members who are part of the LIGO-Virgo collaboration, along with professor and acting assistant professor , both in the Department of Physics at the UW’s Seattle campus. Gundlach and Venkateswara work on instruments to improve the accuracy of detectors. Key and her group .

“This is a huge, collaborative effort — bringing together scientists from across the globe to measure events predicted by Einstein’s theory,” said Gundlach. “Einstein, however, was wrong in claiming that it would be technically impossible to detect gravitational waves.”

Previously confirmed in 2015 and earlier this year all came from mergers of black holes, events that emit no visible light. But since the neutron star merger detected on Aug. 17 also emitted electromagnetic waves, Earth- and space-based observatories picked up signals such as light emissions and gamma ray bursts. It marks the first time that a cosmic event has been detected using both gravitational waves and electromagnetic waves.

LIGO consists of two ultrasensitive detectors in the United States, one at Hanford, Washington and the other in Livingston, Louisiana. Gundlach joined the LIGO team to help those detectors pick up the fantastically small movements caused by gravitational waves, which is no small task given the dynamic environment on our planet.

“Anything that causes drag on the instruments in the detector or affects their precision in any way creates ‘noise,’ which can obscure the tiny signals left by gravitational waves,” said Gundlach.

Gundlach’s group studied subtle disturbances to the LIGO detectors — which would limit the sensitivity of the detectors — and appeared to be caused by residual air molecules in the vacuum chambers or interference from electrostatic sources. Venkateswara joined Gundlach’s team as a postdoctoral researcher in 2011 to develop methods to reduce interference caused by wind, which could blow against the building and obscure signals from gravitational waves.

“The LIGO detectors have had this long-standing problem related to ’tilt’ from wind action,” said Venkateswara. “The instrumentation within the detectors is so sensitive that — even though they operate indoors and in a vacuum — wind blowing outside the building caused the detector to malfunction.”

Venkateswara, Gundlach and doctoral student Michael Ross invented novel devices  that could accurately pick up imperceptibly small tilt of the ground. From 2014 to 2016, Venkateswara and Ross then installed, maintained and tested these sensors at the LIGO detector at Hanford, ensuring that ground tilt could be filtered out of detector measurements. These efforts improved the accuracy and efficiency of observations at Hanford. Now, Venkateswara is preparing to install similar sensors at the Livingston detector.

That will mean more data to analyze for Key and her group at 91Ě˝»¨Bothell, which includes researcher Matt DePies and students Andrew Clark, Holly Gummelt, Paul Marsh, Jomardee Perkins and Katherine Reyes.

The Bothell team works on estimating the physical parameters of gravitational wave data from the detectors, helping to determine their origin in the universe, strength and other properties. They also develop analysis tools to filter out noise from the detectors to improve data quality. Marsh spent this past summer at the Hanford LIGO detector working with the control systems on site.

“These are incredibly precise instruments, but they require a great deal of maintenance, calibration and upkeep,” said Key. “And even after the data come out, there is more work to be done before we can understand the observations themselves.”

These observations add new dimensions to astronomical events that were previously only observable by electromagnetic waves, said Key. Direct — and increasingly precise — detections of gravitational waves also give scientists new opportunities to measure phenomena that, up until recently, were only theories on paper or indirect observations, added Gundlach.

“These collaborations are an ongoing and expanding process,” said Gundlach. “More detectors, better instruments and improved analysis tools — it all gives us so much more insight into figuring out our universe.”

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LIGO is funded by the, and operated by Ěý˛ą˛Ô»ĺĚý, 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 (), the U.K. () and Australia () making significant commitments and contributions to the project. More than 1,200 scientists and some 100  from around the world participate in the effort through the , which includes the GEO Collaboration and the Australian collaboration OzGrav. Additional partners are listed at 

The Virgo collaboration consists of more than 280 physicists and engineers belonging to 20 different European research groups: six from  (CNRS) in France; eight from the  (INFN) in Italy; two in the Netherlands with ; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; the University of Valencia in Spain; and the European Gravitational Observatory, EGO, the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN and Nikhef.

For more information, contact Gundlach at jens@phys.washington.edu, Key at joeykey@uw.edu and Venkateswara at kvenk@u.washington.edu.

The that a third collision of black holes has been detected three billion light years away validates the work of hundreds of scientists, including teams at the 91Ě˝»¨ and 91Ě˝»¨Bothell.

The discovery was made using a detector located at Hanford in eastern Washington and its twin in Louisiana, together known as the (LIGO). This new window in astronomy observes ripples in space and time, as predicted by Albert Einstein. The first two waves generated by the merger of two black holes were detected in 2015. The third, detected in January, is described in a published in the journal Physical Review Letters.

Recently, the 91Ě˝»¨teams have made a significant instrumental contribution to LIGO’s second Observing Run by installing ultra-sensitive tiltmeters at the LIGO Hanford Observatory (LHO), one of the two LIGO observatories in the U.S. These tiltmeters improve the isolation of LIGO from ground motion, thus increasing the duty cycle of LHO under adverse environmental conditions, such as high wind and high ground motion.

Despite 20 mph winds on Jan. 4, the improved seismic isolation at LHO helped identify the nearly simultaneous gravitational-wave signal seen at the two LIGO observatories. Those gravitational-wave signals, which lasted less than a second in the detector, are believed to be from the merger of black holes with masses about 31 and 19 times the mass of the sun, which happened at a distance of more than 3 billion light years. Energy equivalent to twice the mass of the sun was radiated as gravitational waves.

91Ě˝»¨Bothell students are working with scientists at the LIGO Hanford Observatory on data quality and contributing to searches for other gravitational wave sources, said Joey Key, assistant professor of physics at 91Ě˝»¨Bothell, one of the authors of the paper.

“LIGO is opening up a new way to explore our universe, including populations of elusive black holes,” Key said. “This is a significant discovery of a new black hole collision, adding to our map of black hole systems and utilizing the increased sensitivity of the LIGO detectors.”

Key leads the 91Ě˝»¨Bothell LIGO Scientific Collaboration group, which includes lecturer Matt DePies and students Andrew Clark, Holly Gummelt, Paul Marsh, Jomardee Perkins and Katherine Reyes. Physics professor Jens Gundlach, graduate student Michael Ross and Krishna Venkateswara, assistant professor of physics, comprise the LIGO Scientific Collaboration group at the 91Ě˝»¨in Seattle.

“With the detection of a third binary black hole merger, LIGO continues to expand our knowledge about the nature of these events, their astrophysical origins and about the fundamental nature of gravity,” Venkateswara said. “LIGO is allowing us to ‘hear’ the sounds of the universe and many more exciting symphonies await discovery.”

The 91Ě˝»¨research was funded by the National Science Foundation (NSF).

LIGO is funded by the NSF and operated by MIT and Caltech, which conceived and built the project. Financial support for the Advanced LIGO project was led by 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 1,000 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. LIGO partners with the Virgo Collaboration, a consortium including 280 additional scientists throughout Europe supported by the Centre National de la Recherche Scientifique (CNRS), the Istituto Nazionale di Fisica Nucleare (INFN), and Nikhef, as well as Virgo’s host institution, the European Gravitational Observatory. Additional partners are listed at:

For more information, contact Joey Key at 91Ě˝»¨Bothell at 425-352-5497 or joeykey@uw.edu, or Krishna Venkateswara at 301-395-8750 or kvenk@uw.edu.

Grant numbers: NSF 1607385 and 1505861.