Session G05: Mini-Symposium: Gravitational Wave SIG

Gravitational Wave Science: Physics of the Cosmos Programmatic Perspective

NASA's Physics of the Cosmos (PCOS) Program lies at the intersection of physics and astronomy. Its purpose is to explore some of the most fundamental questions regarding the physical forces and laws of the universe: the validity of Einstein's General Theory of Relativity and the nature of spacetime; the behavior of matter and energy in extreme environments; the cosmological parameters governing inflation and the evolution of the universe; and the nature of dark matter and dark energy. The PCOS Program Office engages with the community on behalf of NASA Astrophysics both directly and through the Physics of the Cosmos Program Analysis Group (PhysPAG) and it's associated Science Interest and Analysis Groups (SIGs and SAGs). This includes the Gravitational Wave (GW) SIG. The PCOS Program also supports studies, including ESA-led LISA Laser Interferometer Space Antenna. This talk will discuss the various ways the community can interface with NASA through PCOS on GW activities and the various ways that PCOS is and looks to further engage with GW activities.   

Status of the LISA Space Gravitational Wave Mission

The Laser Interferometer Space Antenna (LISA) is a European Space Agency-led space gravitational wave observatory with expected significant contributions from NASA. LISA will be the first mission to detect and observe lo millihertz gravitational waves from compact galactic binaries and binary black holes, including the mergers of supermassive black holes and extreme mass-ratio inspirals. LISA will be the largest instrument ever constructed, consisting of three Sun-orbiting spacecraft that form an equilateral triangle, with each side measuring 2.5 million kilometers in length. Each spacecraft houses two free-floating test masses (TM), which are protected from all disturbing forces so that they follow pure geodesics in spacetime. A ``drag-free'' control system is supplied with measurements of the TM position and commands external micronewton thrusters to force the spacecraft to fly in formation with the test masses. Laser interferometry is used to measure the minute variations in the distance, or light-travel time, between these free-falling TMs, caused by gravitational waves. The LISA mission is currently in the formulation phase with an expected launch in the early 2030's. This talk will provide an update on the status of this landmark mission, summarize its science return and its involvement in the Astro2020 decadal survey, and describe activities in the U.S. to develop technology and prepare for the science data analysis.   

The NANOGrav search for nanohertz gravitational waves

Supermassive black hole binaries (SMBHBs), and possibly other sources, generate gravitational waves in the nanohertz part of the spectrum. For over a decade the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has been using the Green Bank Telescope, the Arecibo Observatory, and, more recently, the Very Large Array to observe millisecond pulsars. Our goal is to directly detect nanohertz gravitational waves, which cause small correlated changes to the times of arrival of radio pulses from millisecond pulsars. We currently monitor almost 80 millisecond pulsars with sub-microsecond precision and weekly to monthly cadences. A detection of the stochastic gravitational-wave background produced by all the SMBHBs in the universe is close at hand. I will present an overview of NANOGrav Physics Frontiers Center (PFC) activities and summarize our most recent gravitational-wave search results.