Speaker
Description
Discrete ejecta from X-ray binaries are crucial for understanding jet physics from event horizon to parsec scales: launched during accretion state transitions, they probe the link between the accretion flow and jet launching, and then propagate up to $10^11$ gravitational radii, efficiently distributing mass and energy through their interaction with the ISM. Understanding how massive these jets are, where that mass comes from, and whether it is carried primarily by pairs or baryons is essential for constraining the launching mechanism and the relationship between the jet and its environment. New constraints on the ejecta masses have emerged thanks to detailed analyses of XRB radio-flaring episodes (XKAT team), which, combined with kinematic and hydrodynamic modelling of resolved ejecta, have provided new opportunities to trace the mass, energy, and structure of transient jets across a range of times and radii. These results raise a central question: do discrete ejecta obtain their mass direct from the accretion flow, by sweeping up a pre-existing hard-state jet, or through interaction with winds and the external medium? I will address this question using observation-informed relativistic hydrodynamic simulations designed to test the hypothesis that a steady hard-state jet can be swept up by an increasingly fast and dense transition flow, naturally producing the discrete ejecta and flaring episodes we observe. Using state-of-the-art observations as anchor points, these simulations will track how much mass can be swept up or entrained from a pre-existing jet or external medium, and how much must be sourced from the accretion flow itself. This will aim to place constraints on the jet mass, composition and energetics while exploring this formation mechanism as a proof of concept. More broadly, the project aims to unify observations and theory across scales, using radio data and hydrodynamic modelling to build a holistic picture of how X-ray binary jets are launched, mass-loaded, and coupled to their environments.