Detecting Gravitational Waves with NANOGrav/IPTA Pulsars: The Astrophysics of Precision Timing

Abstract: The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) aims to detect low-frequency gravitational waves using long-term pulsar observations with the Arecibo Observatory and the Green Bank Telescope. The 42 millisecond pulsars currently in the pulsar timing array are regularly monitored, and searches are underway for a variety of gravitational wave sources, including: a stochastic background of merging supermassive black hole binaries (SMBHBs), continuous emission from individual SMBHBs, bursts from interacting SMBHBs, and memory bursts from SMBHB mergers. Upper limits on gravitational wave strain have been produced based on the first five years of timing data. Along with collaborators from the International Pulsar Timing Array, NANOGrav has conducted a continuous 24-hour global observation of pulsar J1713+0747 using nine radio telescopes around the world in order to establish the ultimate timing precision of millisecond pulsars.