Alignment of radio jets in the microquasar V4641 Sagittarii with its high-energy structures

Abstract

V4641 Sagittarii (V4641 Sgr) is a unique Galactic microquasar system featuring a stellar-mass black hole accreting matter from a massive companion. One of its intriguing features is the presence of relativistic radio jets almost perpendicular to the observed extended gamma-ray emission, implying significant propagation effects or interactions with the Galactic magnetic field. Here we report observational evidence that the radio jet and the very high-energy (VHE) and ultra high-energy (UHE) gamma-ray emission could be aligned along a common axis, indicating a co-spatial or co-directional origin. This alignment supports a model where synchrotron radio emission, VHE and UHE gamma rays are produced within a single, highly collimated relativistic outflow. Our findings favor scenarios of in-situ particle acceleration up to hundreds of TeV, challenge previous interpretations involving large-scale particle diffusion, and simplify the geometric modeling of the source. This case highlights the potential of V4641 Sgr as a PeVatron candidate within our Galaxy and provides a benchmark for understanding jet composition and magnetic structure in microquasars.

6 pages, 3 figures. Accepted for publication as a Letter in Monthly Notices of the Royal Astronomical Society