Limits to PTA sensitivity: spin stability and arrival time precision of millisecond pulsars

Abstract

Sources of noise in pulsar timing measurements are discussed along with spin stability of neutron stars. Estimates and scaling laws are given for spin noise, timing errors from fluctuations in pulsar magnetospheres, dispersion and scattering in the interstellar plasma, and in the matched filtering technique used to estimate arrival times. The composite noise spectrum is presented and an assessment of the detectability of gravitational waves (GWs) is given in terms of the sources of error and their mitigation. The scaling laws indicate that substantial improvement in sensitivity to GWs can be expected from implementation of new, wideband spectrometers at radio observatories, by using new algorithms to further reduce the levels of plasma propagation effects, and by increasing the number of millisecond pulsars used in pulsar timing arrays.