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A. S. R. Antas

Publications and source records attributed to A. S. R. Antas.

2 recordsLinked to original sources

The evolution of 3C 306 in the galaxy cluster RXCJ1454.4+1622: linking spectral ageing, ICM conditions, and jet dynamics through MHD simulations

We present a methodology for analysing radio sources in galaxy clusters by combining multi-frequency radio observations, X-ray analysis of the intracluster medium (ICM), and three-dimensional magnetohydrodynamic (MHD) simulations, and apply it to the galaxy cluster RXCJ1454.4+1622 and its associated FR II radio galaxy 3C 306 (IC 4516). The radio emission exhibits a curved structure connecting the lobes, likely indicating a complex dynamical evolution influenced by environmental effects. Spectral index and break-frequency maps reveal a relatively homogeneous radiative ageing distribution, with characteristic spectral ages of $\sim220$ Myr and a smooth spatial gradient. From equipartition arguments, we estimate an equivalent jet magnetic field of $2.1 \pm 0.3\,μ$G, consistent with values observed in FR II radio galaxies. These observational constraints are used to initialise non-relativistic MHD simulations exploring three scenarios: jet precession, bulk motion of the source through the ICM, and a combined model including both effects. Neither pure precession nor pure source motion alone fully reproduces the observed morphology, whereas the combined model provides a more consistent representation of the jet curvature and lobe asymmetries. Nevertheless, the simulations indicate that source motion is the dominant mechanism shaping the large-scale radio morphology, with jet precession playing a secondary role. The inferred source velocity ($\sim280$ km s$^{-1}$) and precession timescale ($\sim250$ Myr) are compatible with the spectral ageing constraints. These results suggest that the morphology of 3C 306 is influenced by the interplay between jet precession and dynamical interaction with the ICM, highlighting the role of environmental effects in radio-galaxy evolution in clusters.

astro-ph.HE↗

Orbital motion of NGC 6166 (3C 338) and its impact on the jet morphology at kiloparsec scales

In the central region of the galaxy cluster Abell 2199 (A2199) resides the cD galaxy NGC 6166, which spatially coincides with the 3C 338 radio source. Lobes, jets, and a more detached southern structure (similar to a jet labelled as ridge) are seen at kiloparsec-scale images of 3C 338. This unusual radio morphology has led to the proposition of different hypotheses about its physical origin in the literature. In this work, we study the feasibility of a dynamical scenario where NGC 6166 moves around the X-ray inferred centre of A2199 from the point of view of three-dimensional hydrodynamic simulations. The physical characteristics of the intra-cluster medium in which the jet propagates are constrained to those derived from X-ray observations in the vicinity of NGC 6166. Possible orbits for the jet inlet region are derived from the estimated radial velocity of NGC 6166, while the jet parameters are constrained by parsec-scale interferometric radio observations and the estimated jet power of 3C 338 obtained from radio and X-ray data. Our results show that the hypothesis of NGC 6166 has been moving around the centre of A2199 during the last tens of million of years is compatible with the general radio morphology of 3C 338. Furthermore, the proposed dynamic scenario for the motion of NGC 6166 may be linked to gravitational perturbations induced by the passage of a sub-cluster of galaxies hundreds of millions of years ago.

astro-ph.HE↗