The NANOGrav 15 yr Data Set: Chromatic Gaussian Process Noise Models for Six Pulsars

Understand

Pulsar timing arrays (PTAs) are designed to detect low-frequency gravitational waves (GWs).

• GWs induce achromatic signals in PTA data, meaning that the timing delays do not depend on radio-frequency.
• However, pulse arrival times are also affected by radio-frequency dependent "chromatic" noise from sources such as dispersion measure (DM) and scattering delay variations.
• Furthermore, the characterization of GW signals may be influenced by the choice of chromatic noise model for each pulsar.