Neutron Stars: Nature's Most Versatile Laboratories
At our November 2021 meeting, Professor Xavier Siemens from Oregon State University introduced us to the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). NANOGrav monitors a collection of millisecond pulsars and uses their extremely regular pulsations to measure gravitational waves. It has established increasingly strict limits on the stochastic gravitational-wave background and has recently begun measuring its properties and statistics. The waves that it measures encompass much longer wavelengths (roughly the size of a galaxy) compared to those measured using LIGO and VIRGO and, therefore, represent a range of possible origins different from those that Earthbound detectors can measure.
Some of you might be wondering "What is a pulsar?" It's a spinning, strongly magnetized neutron star that sustains jets of charged particles that periodically point toward Earth as the neutron star spins. (See the image above.) The pulses of electromagnetic radiation associated with these jets form extremely regular patterns, thereby making pulsars extremely accurate clocks. A millisecond pulsar rotates with a period less than 10 milliseconds (0.01 seconds). Correlated variations in the pulses received from different millisecond pulsars provide a measure of very long wavelength gravitational waves.
Ours speaker is Dr Jacob Turner. Dr Turner is helping develop instrumentation that will help expand and refine the insights that NANOGrav provides. He'll share his perspectives on neutron stars, their nature, their properties, and how they provide ways to gain insights into matter and spacetime that are otherwise unobtainable from our tame earthly environs. His description of his presentation is below.
Neutron stars are ultra-dense, rapidly spinning objects born in the violent deaths of more massive stars. Smaller on average than Manhattan, these stars have proven to be among the most multifaceted naturally occurring laboratories every found, with applications ranging from studying the structure of the galaxy, to exploring the existence of exotic states of matter, to detecting perturbations in spacetime created by gravitational waves. In this talk, we will explore what neutron stars are, how they are detected, and how they can be used to better understand our universe.
About Dr Jacob Turner
Jacob Turner is a Postdoctoral Fellow at the Green Bank Observatory, home to the largest fully steerable telescope in the world. He holds a B.A. in Physics from Oberlin College and a PhD in Physics from West Virginia University. He is a member of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), where he works on noise mitigation techniques for interstellar scattering in pulsar timing data. He also serves as a research mentor for the Pulsar Science Collaboratory, which provides opportunities high school and undergraduate students around the United States to participate in high-impact astronomy research. He is currently helping to develop and test the world's first cyclic spectroscopy telescope backend, which will become operational at the Green Bank Observatory in the second half of 2026.