James McKee

Research interests

My research program focuses on radio astronomy of neutron stars; the cores of massive stars left behind after a supernova explosion which spin with frequencies of up to hundreds of rotations per second. Neutron stars emit beams of radiation from their magnetic poles, causing some of them to appear to pulse on and off as the beam sweeps over the Earth - we call these ‘pulsars’.

The rotational frequency of pulsars is very stable and allows them to be used as highly accurate astronomical clocks, with some pulsars being comparable to atomic clocks in timing stability. One of my research interests is using ‘pulsar timing’ to search for tiny variations in the arrival times of pulses which allows us to study extreme binary systems, test theories of gravity, model the behavior of nuclear material under extreme pressure, and detect gravitational waves from the Universe’s population of supermassive black hole binaries.

I am also interested in how radio signals are affected by their passage through ionized material. The radio signals that we receive from pulsars are dispersed and scattered by free electrons in the low-density plasma of the interstellar medium (ISM). By making careful measurements of these effects, we can map the turbulence in the ISM very precisely and identify discrete plasma structures, some of which appear to be ubiquitous features of our galaxy but have no commonly accepted explanation for their origin. Another of my interests is in understanding the origin of bright single pulses (called ‘giant pulses’) seen in a small number of pulsars and their potential connection to fast radio bursts and magnetar emission.

Collaboration Membership:

• North American Nanohertz Observatory for Gravitational Waves (NANOGrav)
• Canadian Hydrogen Intensity Mapping Experiment (CHIME)
• New Extension in Nançay Upgrading LOFAR (NenuFAR)
• European Pulsar Timing Array (EPTA)
• International Pulsar Timing Array (IPTA)

Organizations:

• International Astronomical Union
• Royal Astronomical Society