Real-time evolution of a large-scale relativistic jet

TL;DR

This study presents the first observational evidence of real-time large-scale evolution in a relativistic microquasar jet, revealing morphological changes over two decades that support models of jet-environment interaction.

Contribution

It provides the first direct observational proof of large-scale jet evolution in a microquasar through systematic analysis of archival radio data.

Findings

Morphological variations in GRS 1758-258's jet structure.

Reappearance of the northern radio lobe and hotspot.

Evidence supporting jet instability growth and environmental interaction.

Abstract

Context. Astrophysical jets are ubiquitous in the Universe on all scales, but their large-scale dynamics and evolution in time are hard to observe since they usually develop at a very slow pace. Aims. We aim to obtain the first observational proof of the expected large-scale evolution and interaction with the environment in an astrophysical jet. Only jets from microquasars offer a chance to witness the real-time, full-jet evolution within a human lifetime, since they combine a 'short', few parsec length with relativistic velocities. Methods. The methodology of this work is based on a systematic recalibraton of interferometric radio observations of microquasars available in public archives. In particular, radio observations of the microquasar GRS 1758-258 over less than two decades have provided the most striking results. Results. Significant morphological variations in the extended jet structure of GRS 1758-258 are reported here that were previously missed. Its northern radio lobe underwent a major morphological variation that rendered the hotspot undetectable in 2001 and reappeared again in the following years. The reported changes confirm the Galactic nature of the source. We tentatively interpret them in terms of the growth of instabilities in the jet flow. There is also evidence of surrounding cocoon. These results can provide a testbed for models accounting for the evolution of jets and their interaction with the environment.