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 8 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.
Highlights
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
Astrophysical jets are observed in a variety of environments including young stellar and Herbig-Haro (HH) objects (Reipurth & Bally 2001), planetary nebulae (Sahai & Trauger 1998), microquasars (Mirabel & Rodríguez 1999), active galactic nuclei (AGN), and distant quasars (Begelman et al 1984)
This mechanism is characterized well because the mass accretion and ejection events evolve fast enough to be appropriately sampled with multi-wavelength observations of both microquasars (Mirabel et al 1998; Mirabel & Rodríguez 1994a; Fender et al 1999) and AGN (Gómez et al 2000; Marscher et al 2002), where these processes occur on time scales from hours or days to years, respectively
Summary
Astrophysical jets are observed in a variety of environments (de Gouveia Dal Pino 2005) including young stellar and Herbig-Haro (HH) objects (Reipurth & Bally 2001), planetary nebulae (Sahai & Trauger 1998), microquasars (Mirabel & Rodríguez 1999), active galactic nuclei (AGN), and distant quasars (Begelman et al 1984) These outflows are triggered when the magnetic field taps the rotational energy from a central compact object or disk (Blandford & Payne 1982; Kylafis et al 2015). Its Galactic nature has never been confirmed because of the lack of optical and infrared spectra of the companion star (Luque-Escamilla et al 2014), GRS 1758−258 appears as a very bright and persistent hard X-ray source towards the Galactic centre region (Sunyaev et al 1991) This source has strong spectral similarities in X-rays with the classical black hole candidate Cygnus X-1 (Main et al 1999). This provides us with a unique set of highly sensitive maps with an angular resolution that is well suited to exploring the evolution of the GRS 1758−258 jets over more than a decade
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