Colloq Abstract - Tim Dolch
May 27, 2022
11:00am Mountain
Tim Dolch (Hillsdale College / Eureka Scientific)
NANOGrav's Search for Gravitational Waves, Including Interstellar Medium Bonus Science
Abstract
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) NSF Physics Frontiers Center is a pulsar timing array collaboration conducting long-term observations of radio millisecond pulsars. We use the Green Bank Telescope, the Karl G. Jansky Very Large Array, and the Canadian Hydrogen Intensity Mapping Experiment (CHIME). The line-of-sight to each pulsar acts as a detector arm for measuring pulse time-of-arrival perturbations due to gravitational waves (GWs). A common signal has been detected in NANOGrav’s 12.5-year dataset, and the characteristic pairwise correlations predicted from the quadrupolar nature of GWs are expected in a future data release. Optical and infrared structures associated with radio pulsars can also help characterize their lines-of-sight. In particular, bow-shock pulsar wind nebulae, such as the Guitar Nebula, can characterize the environments of their associated neutron stars. Additionally, timing observations at frequencies lower than standard timing frequencies (such as with the Long-Wavelength Array) can probe interstellar medium (ISM) density fluctuations with improved accuracy. Finally, we look at the overall turbulence spectrum of the ISM across the Galaxy, putting together data from radio timing observations, pulsar wind nebulae, and in-situ ISM data from outer solar system spacecraft.
