The observation of the merger of two neutron stars in August 2017 with both gravitational waves and light began the era of gravitational multi-messenger astronomy. While much can still be learned from the mergers of two massive compact objects, it is important to also be listening for other sounds in the symphony of gravitational waves. Certain types of supernovae should emit gravitational waves along with light as an old and massive star collapses into an ultra-dense neutron star. Multi-messenger observations of these supernova could help us learn a great deal about how and why these spectacular explosions occur, and about the neutron star that forms as a result. Multi-messenger observations could also be a key to unlocking the mysterious origin of short, bright flashes of radio emission from space called fast radio bursts. This award will also cover work in identifying and getting rid of sources of noise picked up by the LIGO interferometers that can interfere with detecting real signals from space. This work is particularly important as LIGO continues to look for these new types of gravitational wave sources which don't have the characteristic "chirp" that occurs when black holes or neutron starts collide. Annual STEM outreach work serving the Navajo nation north of Embry-Riddle, also supported by this grant, is one way in which LIGO members can share this new and exciting frontier in science with the broader community.
Efforts in multi-messenger astronomy, including searches in coincidence with core-collapse supernovae and radio transients, will enhance LIGO science while providing many opportunities for student involvement. Core-collapse supernovae are an exciting target for multi-messenger astronomy. The reconstruction of a gravitational wave from a core-collapse supernova would address a number of open questions in astrophysics, including the mechanism of the explosion itself as well as fundamental questions about neutrino interactions and the neutron star equation of state. In the next few years, the improved sensitivity of Advanced LIGO combined with more sophisticated algorithms for detection and parameter estimation of supernova signals will greatly enhance LIGO's contributions to supernova astrophysics, and future interferometers carry even more promise. Another area of multi-messenger astronomy which LIGO has undertaken is the search for transient gravitational waves in coincidence with astrophysical sources of radio transients of duration on the scale of milliseconds. These could be emitted simultaneously with gravitational waves due to scenarios ranging from neutron star asteroseismology to cosmic string cusps. Gravitational wave astronomy has the potential to shed light on several types of radio emission, possibly including fast radio bursts. The search for gravitational wave bursts is made more difficult by the presence of transient terrestrial background, resulting from a combination of environmental disturbances and behavior of the interferometers themselves. Understanding these environmental disturbances and removing them from interferometric data is critical in conducting sensitive searches for gravitational waves, as it can mean the difference between a statistically significant gravitational wave detection and a sub-threshold event. This grant will support substantial effort in detector characterization, the identification and mitigation of non-astrophysical background in the interferometers and application of vetoes to eliminate them. This award also facilitates science education and outreach at every level from high school to graduate student.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
