The Laser Interferometer Gravitational-wave Observatory (LIGO) is now able to explore the sky in a whole new way, poised to detect extremely tiny ripples in the geometry of spacetime that are generated by distant astrophysical objects such as black holes, neutron stars, and supernovas. A new "science run" in 2009-2010, coordinated with the French-Italian VIRGO detector, will provide the most sensitive data yet to be searched for gravitational wave signals. This project connects the gravitational-wave detection effort with mainstream astronomy by carrying out gravitational-wave burst searches and by leading a campaign of prompt optical telescope (and potentially X-ray and radio telescope) follow-up observations of gravitational-wave burst candidates during the 2009-2010 science run. In addition, it supports data quality diagnostics and an end-to-end test system using simulated signals in the detectors, in preparation for establishing the validity of any gravitational-wave signal that is detected.
This project helps to maximize NSF's investment in LIGO by increasing the chance of detecting a distinct gravitational-wave signal in the 2009-2010 science run. A prompt optical transient, associated with a gravitational-wave burst candidate, would help establish the reality of the gravitational-wave signal and also provide valuable additional information about its source. Developing and exercising this capability now prepares for the future, when Advanced LIGO will detect gravitational-wave signals regularly that can be connected to astronomical observations. Besides the benefits to astrophysics, this project strengthens international cooperation among gravitational-wave scientists, builds connections with the optical astronomy community, and contributes to education by providing research experience for students.
Almost all of what we know about the universe outside of our solar system comes from electromagnetic radiation that reaches us: light that we see with our eyes or with telescopes, radio waves that we detect with large dishes or arrays of antennas, and X-rays and gamma rays that we collect with specialized detectors on satellites that we have launched into space. But we are working with colleagues around the world to open up a new kind of astronomy based on detecting gravitational waves reaching Earth. These waves are predicted by Einstein's theory of relativity but have not yet been detected because they are incredibly weak. However, the large LIGO gravitational-wave detectors in the U.S., along with similar Virgo and GEO detectors in Europe, have been specially constructed and tuned up to detect these feeble waves. As the observations improve, the data will reveal unique information about massive stars, black holes, neutron stars, and other remarkable objects in our universe. Our project, funded by NSF, has developed and tested some important new capabilities that improved recent searches for gravitational waves and promise to do so again in the future. We reasoned that transient "events" that produce gravitational waves are likely to also produce flashes or afterglows of light, X-rays, or radio waves -- the "messengers" of traditional astronomy. The trick is to look for those short-lived signals in the right place before they fade away. So we set up a system to analyze gravitational wave data within minutes after it was collected to find candidate events and determine where in the sky they seemed to be coming from. Then, we arranged with several astronomers to point their telescopes at those sky locations as soon as possible after we alerted them about an event. The whole system took a lot of planning, software development, testing, and human validation, but we got it all to work during the 2009-2010 LIGO-GEO-Virgo science runs. Some of its intellectual merits were: giving us novel scientific results, strengthening our relationships with traditional astronomers, and giving us valuable experience to build on for improving our methods and multi-messenger science capabilities for the future. The testing we did also validated the response of our detectors and data analysis methods. Along the way, this project provided valuable training and direct research experience for four graduate students, four undergraduate students, and two high school students with diverse backgrounds. As other broader impacts, I was able to incorporate some gravitational wave astrophysics and detector technologies into the classes I taught, and I reached additional audiences of promising young scientists through summer lecture series that I gave about gravitational waves and data analysis. My students and I also staffed a number of public science outreach events. The gravitational wave science community stands as a positive example of international cooperation to overcome technical challenges and pursue new scientific knowledge.
