A MeerKAT view of the parsec-scale jets in the black-hole X-ray binary GRS 1758–258

¹ Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
² Università degli Studi di Milano Bicocca, Dipartimento di Fisica, Piazza dell’Ateneo Nuovo, 1 – 20126 Milano Casella, Italy
³ University of Oxford, Department of Physics, Astrophysics, Denys Wilkinson Building, Keble Road OX1 3RH Oxford, United Kingdom
⁴ ASTRON, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
⁵ Department of Astrophysics/IMAPP, Radboud University, P.O. Box 9010 6500 GL Nijmegen, The Netherlands
⁶ Departamento de Física, Escuela Politécnica Superior de Jaén, Universidad de Jaén, Campus Las Lagunillas s/n, 23071 Jaén, Spain
⁷ Departamento de Ingeniería Mecánica y Minera, Escuela Politécnica Superior de Jaén Universidad de Jaén, Campus Las Lagunillas s/n, A3, 23071 Jaén, Spain
⁸ Department of Physics and Electronics, Rhodes University, P.O. Box 94 Makhanda 6140, South Africa
⁹ South African Radio Astronomy Observatory, 2 Fir Street, Observatory 7925, South Africa

^★ Corresponding author: isabella.mariani@inaf.it

Received: 7 July 2025
Accepted: 16 September 2025

Abstract

Context. Jets from accreting black-hole (BH) X-ray binary (XRB) systems are powerful outflows that release a large fraction of the accretion energy to the surrounding environment, providing a feedback mechanism that may alter the properties of the interstellar medium (ISM). Studying accretion processes alongside their feedback on the environment may enable one to estimate the matter and energy input and output around accreting BHs.

Aims. We aim to study the extended jet structures around the BH XRB GRS 1758–258. First observed in VLA data, these parsec-scale jet structures originate from jet-ISM interaction, and are characterised by a peculiar Z-shape morphology.

Methods. Using the MeerKAT radio telescope we observed GRS 1758–258 in the L band for a total exposure of 7 hr. Following a calorimetry-based method originally proposed for active galactic nuclei (AGN) and later applied to X-ray binaries, we estimated the properties of the jets and of the surrounding ISM.

Results. We detect a jet and a counter-jet terminating in bow-shock structures induced by their interaction with the ISM. We identified both synchrotron and bremsstrahlung emitting regions within the northern lobe, while the southern lobe is dominated by thermal emission. We measured an ISM particle density of between 10 and 40 cm⁻³ across both the northern and southern jets, slightly lower in the northern region. The estimated ages of the two jet sides range from 6 to 51 kyr, with the northern jet seemingly younger than the southern one. The time-averaged transferred jet energy for both jets falls between 4.4 × 10³³ and 3.3 × 10³⁶ erg s⁻¹, with slight differences between the northern and southern jets ascribed to different local environmental conditions. Comparing the new MeerKAT with archival VLA observations, we measured a proper motion of a portion of the northern jet of ∼130 mas/year.

Conclusions. Jet-ISM interaction structures on both sides of GRS 1758–258 reveal different local ISM properties. The comparison between the morphology of these structures and those from other XRBs indicates that the lobes in GRS 1758–258 may be younger and may result from a number of jet activity phases. The estimated time-averaged energy transferred to the environment is slightly lower than, but comparable to, that observed in other XRBs, consistent with the younger age of the lobes in GRS 1758–258 relative to those of other systems.