Galactic-scale evolution of classical and complex radio galaxies

Impact of ambient morphology and jet geometry

¹ Istituto Nazionale di Astrofisica (INAF) – Istituto di Radioastronomia (IRA), via Gobetti 101, 40129 Bologna, Italy
² National Centre for Nuclear Research, Pasteura 7, 02-093 Warsaw, Poland
³ Indian Institute of Astrophysics, Sarjapur Rd., Koramangala, Bangalore 560034, India
⁴ Núcleo de Astrofísica, Universidade Cidade de São Paulo R. Galvão Bueno 868, Liberdade, São Paulo, SP, 01506-000, Brazil
⁵ INAF/Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese, Italy
⁶ Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
⁷ Department of Physics, University of Pretoria, Private Bag X20 Hatfield 0028, South Africa
⁸ Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Makhanda 6140, South Africa
⁹ Istituto Nazionale di Astrofisica (INAF) – Istituto di Astrofisica e Planetologia Spaziali (IAPS), via del Fosso del Cavaliere 100, 00133 Roma, Italy

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 2 January 2026
Accepted: 9 April 2026

Abstract

Context. Extragalactic jets, following their launching, exhibit a wide range of propagation orientations relative to the host galaxy’s principal axis. This initial (mis)alignment has been shown to exert a substantial influence on a jet’s subsequent large-scale evolution.

Aims. With this study, our aim is to investigate the spatiotemporal evolution of jets as a function of their propagation direction within their triaxial hosts, which introduces varying degrees of environmental hindrance, and as a function of internal jet properties (while maintaining identical jet power: 3 × 10⁴⁴ erg/s), which introduces varying collimation and thrust.

Methods. Observational data on extended radio sources were reanalyzed to identify key morphological and dynamical traits arising from variations in jet orientation and intrinsic properties. These findings were then systematically tested using a suite of 3D relativistic magneto-hydrodynamic simulations through the generation of dynamical and radiative maps.

Results. When a jet propagates along its host’s major axis (the path of maximal environmental resistance), it produces an X-shaped morphology, with a secondary lobe that aligns along the minor axis and co-evolves actively alongside the active jet. At intermediate angles to the major axis, the jet morphology transitions into a double-boomerang structure with notably curved lobes. Such lobes are interestingly regenerative due to both backflow and jet precession mechanisms, making it difficult to disentangle their origin. Jets propagating along the minor axis (path of minimal resistance) exhibit faster propagation, forming classical double-lobed sources. With increased thrust and improved collimation (keeping jet power constant), these jets advance even more rapidly and potentially evolve into giant radio galaxy candidates. Counterexample sources that deviate from these traits were also modeled. The spatial variation of internal turbulence showed significant fluctuations below ∼1 kpc, with stronger magnetic fields further suppressing these irregularities. The magnetic field plays a key role in the radiative appearance of these sources, modulating features such as missing or one-sided (wing) lobe emission, filamentary structures, and warmspot versus hotspot formation.