Abstract
A subclass of extragalactic radio sources known as winged radio galaxies has puzzled astronomers for many years. The wing features are detected at radio wavelengths as low-surface-brightness radio lobes that are clearly misaligned with respect to the main lobe axis. Different models compete to account for these peculiar structures. Here, we report observational evidence that the parsec-scale radio jets in the Galactic microquasar GRS 1758-258 give rise to a Z-shaped radio emission strongly reminiscent of the X and Z-shaped morphologies found in winged radio galaxies. This is the first time that such extended emission features are observed in a microquasar, providing a new analogy for its extragalactic relatives. From our observations, we can clearly favour the hydrodynamic backflow interpretation against other possible wing formation scenarios. Assuming that physical processes are similar, we can extrapolate this conclusion and suggest that this mechanism could also be at work in many extragalactic cases.
Highlights
A subclass of extragalactic radio sources known as winged radio galaxies has puzzled astronomers for many years
Here, we report that the Galactic microquasar GRS 1758-258 has a large-scale Z-shaped morphology that mimics that of many extragalactic winged radio galaxies (WRGs)
Jansky Very Large Array (VLA), in 2016, we conducted a new observation of GRS 1758-258, which had remained unmonitored by sensitive radio interferometers for nearly a decade
Summary
A subclass of extragalactic radio sources known as winged radio galaxies has puzzled astronomers for many years. A key aspect here is whether the WRG shape somehow originates from the final interaction between the jets and their environment In this case, one expects that the underlying physics will be hydrodynamical, being mainly dependent on a few basic parameters, such as the jet density, medium density and jet power, among others. The relationship between these parameters is anticipated to follow a dynamic similarity at different scales This jet/medium interaction hypothesis would become strongly supported if WRG-analogues were found to exist in downscaled systems with bipolar relativistic jets, such as stellar microquasars[19, 20]. By appropriately scaling the dynamic similarity laws of fluid mechanics to the very different environments of microquasar and extragalactic jet sources, there is no a priori argument against this parallelism applying to regions far beyond the central engine of these systems where the lobes form. Its arcmin radio jets change in morphology over a matter of a few years, and based on causality arguments the source cannot be located
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