Searching for Mass Concentrations with Precision Pulsar Timing

This papers searches for evidence of mass concentrations along the path of radio pulses in the PPTA2 survey data release. Radio pulse travel times are influenced via gravitational fields along the path from the source to the observer. Transient time delays in transit are a useful measure of the matter distribution along the path. Many pulsars have very well understood timing solutions with predicable arrival times and can be used to sample the mass variation. Changes in the source, observer and mass concentration positions produce changes in arrival times which can be significant for precision pulsar times. Twelve candidates are reported from this search.