Dynamics of relativistic radio jets in asymmetric environments

Abstract

We have carried out relativistic three-dimensional simulations of high-power radio sources propagating into asymmetric cluster environments. We offset the environment by 0 or 1 core radii (equal to 144 kpc), and incline the jets by 0, 15, or 45○ away from the environment centre. The different environment encountered by each radio lobe provides a unique opportunity to study the effect of environment on otherwise identical jets. We find that the jets become unstable towards the end of the simulations, even with a Lorentz factor of 5; they nevertheless develop typical FR II radio morphology. The jets propagating into denser environments have consistently shorter lobe lengths and brighter hotspots, while the axial ratio of the two lobes is similar. We reproduce the recently reported observational anti-correlation between lobe length asymmetry and environment asymmetry, corroborating the notion that observed large-scale radio lobe asymmetry can be driven by differences in the underlying environment.

Selecting and modelling remnant AGNs with limited spectral coverage

“…bounded by the FWHM of a restoring beam), it is reasonable to suspect that the plasma contained here will have been injected at approximately the same age. This means that the associated radio spectrum is likely that of the JP model, however we note the results of Turner et al (2018a), Mahatma et al (2020) and Yates-Jones et al (2021, 2022 who show that mixing of plasma ages may violate this assumption.…”

RAiSE: simulation-based analytical model of AGN jets and lobes

“…The RAiSE HD emissivity model is based on Lagrangian particles from the hydrodynamic simulations of Yates-Jones et al (2022); these simulations are identical to those studied by Yates-Jones et al (2021) but additionally include particles to incorporate radiative loss mechanisms as presented in Turner et al (2018a). In this paper, we focus exclusively on differences between the dynamics of the models and any resulting differences in spatial brightness distributions; Yates-Jones et al (2022) provide a verification of the RAiSE HD integrated luminosity through a comparison with an alternative particlebased brightness calculation.…”

“…The two hydrodynamic simulations of Yates-Jones et al (2022) both consider a high-powered FR-II jet (Qtot = 10 38.8 W, or Q = 10 38.5 W) with Lorentz factor γj = 5 and half-opening angle θj0 = 10 degrees (for the inner, uncollimated section of the jet), expanding into a cluster environment at redshift z = 0.05. The environment is modelled as a spherically symmetric King profile with core density of ρc = 2.41 × 10 −24 kg m −3 , core radius of rc = 144 kpc, and slope described by the coefficient β = 0.38 (for details, see Yates-Jones et al 2021). The simulations either have the jets expand outwards from the cluster centre or expanding radially outwards (inwards) for the jet (counterjet) from a cluster radius of r = rc.…”

“…The Taub-Mathews equation of state is used to relate fluid quantities (Mathews 1971). We assume the same spherically symmetric King profile as described in Section 4.1, and originally Yates-Jones et al (2021). The jet injection region is defined as a sphere of radius 1 kpc with the velocity set to vj = 0.01c (i.e.…”

“…Extending this analysis, Turner & Shabala (2015) showed that this is no longer the case in more complex environments, with older radio sources expected to be more elongated, a result consistent with observations. While the analytical models described above provide an excellent description of late-time lobe evolution, hydrodynamic and magnetohydrodynamic simulations (Sutherland et al 2007;Hardcastle & Krause 2013;English et al 2019;Yates-Jones et al 2021) highlight another important, earlier phase of radio source evolution. This 'jet breakout' phase (Sutherland et al 2007) corresponds approximately to the transition between the jets propagating through the clumpy interstellar medium (ISM) of their host galaxy (which efficiently isotropises the jet momentum flux into a quasi-spherical bubble), and the larger lobe formation scale.…”