Galactic-scale evolution of classical and complex radio galaxies

Gourab Giri; Prajnadipt Ghosh; Ravi Joshi; Anderson Caproni; Paola Rossi; Gianluigi Bodo; Sayan Kundu; Kshitij Thora; Swarna Chatterjee; Dario Borgogno; Valerio Vittorini; Marco Tavani

doi:10.1051/0004-6361/202658848

Galactic-scale evolution of classical and complex radio galaxies

Gourab Giri
, Prajnadipt Ghosh
, Ravi Joshi
, Anderson Caproni
, Paola Rossi
, Gianluigi Bodo
, Sayan Kundu
, Kshitij Thora
, Swarna Chatterjee
, Dario Borgogno
, Valerio Vittorini
, Marco Tavani

Istituto Nazionale di Astrofisica
INAF - Istituto di Radioastronomia
National Centre for Nuclear Research
Indian Institute of Astrophysics
Universidade Cidade de São Paulo R. Galvão Bueno
Osservatorio Astrofisico di Torino
University of Pretoria
Rhodes University
INAF-Istituto di Astrofisica e Planetologia Spaziali
Istituto di Astrofisica e Planetologia Spaziali

Research output: Contribution to journal › Article › peer-review

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.

Original language	English
Article number	A279
Number of pages	24
Journal	Astronomy & Astrophysics
Early online date	27 May 2026
DOIs	https://doi.org/10.1051/0004-6361/202658848
Publication status	Published - 31 May 2026

Funding

GG thanks Sushmita Agarwal for organizing an open discussion session at Indian Institute of Technology Indore, India, which sparked the idea of pursuing such study from a numerical perspective. GG and KT acknowledges financial support from the South African Department of Science and Innovation’s National Research Foundation under the ISARP RADIOMAP Joint Research Scheme (DSI-NRF Grant Number 150551). GG acknowledges the travel support from Gianluigi Bodo and Paola Rossi (for a visit to Osservatoria Astrofisico di Torino – INAF) through Ob.Fu. 1.05.01.89.01 and ‘Ricerca di base gruppo extragalattico’. SK gratefully acknowledge support by the Science and Technology Facilities Council (STFC) through grant ST/X001067/1. The authors acknowledge the Centre for High Performance Computing (CHPC), South Africa, for providing computational resources to this research project (https://www.chpc.ac.za/). We acknowledge the use of the ilifu cloud computing facility – https://www.ilifu.ac.za/, a partnership between the University of Cape Town, the University of the Western Cape, Stellenbosch University, Sol Plaatje University, the Cape Peninsula University of Technology and the South African Radio Astronomy Observatory. The ilifu facility is supported by contributions from the Inter University Institute for Data Intensive Astronomy (IDIA – a partnership between the University of Cape Town, the University of Pretoria and the University of the Western Cape), the Computational Biology division at UCT and the Data Intensive Research Initiative of South Africa (DIRISA).

Keywords

magnetohydrodynamics (MHD)
methods: numerical
ISM: jets and outflows
galaxies: jets
galaxies: structure

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10.1051/0004-6361/202658848Licence: CC BY

Cite this

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title = "Galactic-scale evolution of classical and complex radio galaxies",

abstract = "Context. Extragalactic jets, following their launching, exhibit a wide range of propagation orientations relative to the host galaxy{\textquoteright}s principal axis. This initial (mis)alignment has been shown to exert a substantial influence on a jet{\textquoteright}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 {\texttimes} 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{\textquoteright}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.",

keywords = "magnetohydrodynamics (MHD), methods: numerical, ISM: jets and outflows, galaxies: jets, galaxies: structure",

author = "Gourab Giri and Prajnadipt Ghosh and Ravi Joshi and Anderson Caproni and Paola Rossi and Gianluigi Bodo and Sayan Kundu and Kshitij Thora and Swarna Chatterjee and Dario Borgogno and Valerio Vittorini and Marco Tavani",

year = "2026",

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day = "31",

doi = "10.1051/0004-6361/202658848",

language = "English",

journal = "Astronomy \& Astrophysics",

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T1 - Galactic-scale evolution of classical and complex radio galaxies

AU - Giri, Gourab

AU - Ghosh, Prajnadipt

AU - Joshi, Ravi

AU - Caproni, Anderson

AU - Rossi, Paola

AU - Bodo, Gianluigi

AU - Kundu, Sayan

AU - Thora, Kshitij

AU - Chatterjee, Swarna

AU - Borgogno, Dario

AU - Vittorini, Valerio

AU - Tavani, Marco

PY - 2026/5/31

Y1 - 2026/5/31

N2 - 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.

AB - 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.

KW - magnetohydrodynamics (MHD)

KW - methods: numerical

KW - ISM: jets and outflows

KW - galaxies: jets

KW - galaxies: structure

U2 - 10.1051/0004-6361/202658848

DO - 10.1051/0004-6361/202658848

M3 - Article

SN - 0004-6361

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A279

ER -

Galactic-scale evolution of classical and complex radio galaxies

Abstract

Funding

Keywords

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