TY - THES ID - 134993003 TI - On the stability and evolution of relativistic astrophysical jets AU - Millas, Dimitrios AU - Keppens, Rony AU - Porth, Oliver AU - KU Leuven. Faculty of science. Department of mathematics PY - 2019 PB - Leuven KU Leuven. Faculty of Science DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:134993003 AB - Several observations of astrophysical jets show evidence of a structure in the direction perpendicular to the jet axis, leading to "spine & sheath" models of jets. We will examine such case of a two-component jet: a highly relativistic inner jet and a slower but still relativistic outer jet, surrounded by an unmagnetized environment.Hydrodynamic jets and jets with poloidal magnetic field have already been examined and found susceptible to a relativistically enhanced, Rayleigh-Taylor type instability (Meliani & Keppens 2007, 2009).We first extend this work using a realistic helical magnetic field topology, performing 2.5D & 3D simulations using the MPI-AMRVAC code. The toroidal component of the magnetic field may provide sufficient hoop stress to suppress these instabilities. Differential rotation between the jet components is also incorporated in our study. The stability is determined in terms of the average Lorentz factor (deceleration) and effective cross-section of the jet (decollimation).The next step is to post-process the simulation data with a radiative transfer code to detect effects of the (in)stabilities in the synchrotron emission from the jet and the polarization properties.In the last part, we focus on the interaction between the relativistic jet of the X-ray binary SS433 and a supernova remnant, W50. We perform relativistic 3D simulations, capturing both the initial supernova explosion and the propagation of the jet in order to recreate the observed asymmetric, elongated shape of W50. ER -