| Kathrin Grunthal||ORATED|
We will explore the method of precision pulsar timing as a tracer of space-time deformations both in the vicinity of the pulsar, caused by ist host system, as well as a probe of gravitational waves (GWs) crossing the lines-of-sight between multiple pulsars and the Earth. Subsequently, this work is set up in a two-fold manner: In the first part, we present an analysis of the millisecond pulsar (MSP) J1618-3921 using radio observations from MeerKAT, Parkes and Nancay. We investigate its emission behavior, comprising a change of its mean stable profile, as well as a Rotating-Vector-Model fit of the linear polarisation position angle swing. The main focus lies on the following timing analysis using the 23-year long timing baseline stretching back to the discovery observations in 1999. We present the first timing solution of this pulsar containing a binary model and a mass estimate for both the pulsar and its companion. We also discuss the measurement of the change of the orbital period, which strongly diverges from its expected value, indicating the presence of a third massive object in the pulsar's vicinity. With J1618-3921 belonging to the class of eccentric MSPs, all these results shed new light on this enigmatic pulsar population, raising new questions to current stellar evolution models. The second part holds a theoretical approach to the detection of continuous GWs with current pulsar timing arrays (PTAs). We discuss the mathematical framework of PTA sensitivity curves and its impementation. We apply it to the European Pulsar Timing Array (EPTA) using its latest 25 pulsar data set, followed by a comparison with the Northern American Nanohertz Observatory for Gravitational Waves (NANOGrav), as well as the full GW detector network available in the mid 2030s.