On Lorentz Variability of Magnetically Dominated Relativistic Outflows

TL;DR

This paper demonstrates that Lorentz transformations can cause apparent variability in magnetically dominated relativistic outflows, linking observed temporal changes to magnetic field topology without intrinsic plasma fluctuations.

Contribution

It introduces the concept of magnetic Lorentz seismology, showing how Lorentz mapping of stationary magnetic fields produces observable variability in relativistic jets.

Findings

Lorentz transformation maps magnetic topology into apparent variability.

Variability frequency scales linearly with Lorentz factor.

Magnetic field structure can be inferred from observed variability.

Abstract

In this Letter, we show that magnetized relativistic outflows can exhibit a relativistic effect in which Lorentz transformation maps magnetic field topology into apparent temporal variability in the observer's frame. Using a force-free Beltrami configurations as representative equilibria of magnetically dominated outflows, we demonstrate that Lorentz mapping of stationary helical magnetic field produces quasi-periodic modulation of observable electromagnetic signatures, without invoking intrinsic plasma variability. This effect may be described as an aberration of force-free magnetic fields under Lorentz transformation. The characteristic frequency of the time variability is determined by the helical wave-number of the magnetic field, the viewing angle, and the bulk Lorentz factor of the jet outflow, and scales linearly with $\Gamma$. This establishes a purely kinematic relativistic origin of variability and introduces the concept of magnetic Lorentz seismology: the inference of magnetic field structure in relativistic outflows directly from observed temporal variability.