# Lagrangian solutions to the Vlasov-Poisson system with a point charge

## TL;DR

This paper proves the existence of global Lagrangian solutions for the 3D Vlasov-Poisson system with a point charge, extending previous Eulerian results by demonstrating solutions are transported along flow trajectories.

## Contribution

It introduces a new existence proof for solutions with a point charge, utilizing anisotropic regularity and singular integral techniques, expanding the theoretical understanding of the system.

## Key findings

- Existence of global Lagrangian solutions under certain decay and energy bounds.
- Solutions are transported by flow trajectories, confirming a Lagrangian perspective.
- Extension of Eulerian theory to include point charges with rigorous mathematical proof.

## Abstract

We consider the Cauchy problem for the repulsive Vlasov-Poisson system in the three dimensional space, where the initial datum is the sum of a diffuse density, assumed to be bounded and integrable, and a point charge. Under some decay assumptions for the diffuse density close to the point charge, under bounds on the total energy, and assuming that the initial total diffuse charge is strictly less than one, we prove existence of global Lagrangian solutions. Our result extends the Eulerian theory of [16], proving that solutions are transported by the flow trajectories. The proof is based on the ODE theory developed in [8] in the setting of vector fields with anisotropic regularity, where some components of the gradient of the vector field is a singular integral of a measure.