Synthetic Observations of Simulated Radio Galaxies. I. Radio and X‐Ray Analysis

Tregillis, I. L.; Jones, T. W.; Ryu, Dongsu

doi:10.1086/380756

Cited by 37 publications

(30 citation statements)

References 34 publications

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“…For example, Cheung et al (2007) demonstrated that observed proper motions of forward (superluminal) and reverse (subluminal) knots can be precisely reproduced by a 1D relativistic MHD simulation model. A very interesting work was presented in a series of papers by Jones et al (2001), Tregillis et al (2001aTregillis et al ( ,b, 2004, O'Neil et al (2006), and others where the authors have conducted extensive studies of high-resolution 2D and 3D MHD simulations of supersonic jets, exploring the influence of the jet Mach number and the ambient medium A88, page 2 of 12 on jet propagation and energy deposition over long distances. Obviously, only 3D simulations can reproduce the obliquity of the features in some jets observed with very high angular resolution, e.g.…”

Section: Jets and Multiple Oblique Shocksmentioning

confidence: 99%

Active galactic nuclei jets and multiple oblique shock acceleration: starved spectra

Meli¹,

Biermann

2013

A&A

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Context. Shocks in jets and hot spots of active galactic nuclei (AGN) are one prominent class of possible sources of very high-energy cosmic-ray particles (above 10 18 eV). Extrapolating their spectrum to their plausible injection energy from some shock implies an enormous hidden energy for a spectrum of index ∼−2. Some analyses suggest the particles' injection spectrum at source to be as steep as −2.4 to −2.7, which exacerbates the problem, by a factor of 10 6 . Nevertheless, it seems implausible that more than at the very best 1/3 of the jet energy goes into the required flux of energetic particles, thus one would need to allow for the possibility that there is an energy problem, which we would like to address in this work. Aims. Sequences of consecutive oblique shock features, or conical shocks, have been theoretically predicted and eventually observed in many AGN jets. Based on that, we use by analogy the Comptonization effect and propose a scenario of a single injection of particles consecutively accelerated by several oblique shocks along the axis of an AGN jet. Methods. We developed a test-particle approximation Monte Carlo simulations to calculate particle spectra by acceleration at such a shock pattern while monitoring the efficiency of acceleration by calculating differential spectra. Results. We find that the first shock of a sequence of oblique shocks establishes a low-energy power-law spectrum with ∼E −2.7 . The following consecutive shocks push the spectrum up in energy, rendering flatter distributions with steep cut-offs, and characteristic depletion at low energies, which could explain the puzzling apparent extra source power. Conclusions. Our numerical calculations show a variation of spectral indices, a general spectral flattening, and starved spectra, which connect to the relativistic nature of the shocks, the multiple shock acceleration conditions, and the steepness of the magnetic field to the shock normal. This helps in understanding the jet-magnetic field geometry and the irregular or flat spectra observed in many AGN jets (e.g., CenA, 3C 279, PKS 1510-089). Furthermore, the E −2.4 − E −2.7 ultra-high-energy cosmic-ray injected source spectra claimed by many authors might be explained by the superposition of several, perhaps many, emission sources, all of which end their particle shock-acceleration sequence with flatter, starved spectra produced by two or more consecutive oblique shocks along their jets. It might also imply a mixed component of the accelerated particles above 10 19 eV. Moreover, the present acceleration model can explain the variability of inverted gamma-ray spectra observed in high redshifted flaring extragalactic sources.

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Section: Jets and Multiple Oblique Shocksmentioning

confidence: 99%

Active galactic nuclei jets and multiple oblique shock acceleration: starved spectra

Meli¹,

Biermann

2013

A&A

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“…Additionally, we include a population of passive, nonthermal, relativistic cosmic ray particles in our models. These cosmic rays are transported, injected, accelerated, and aged in a self-consistent fashion to enable the construction of realistic synthetic observations (see, e.g., Jones et al 1999;Tregillis et al 2001aTregillis et al , 2004P. J. Mendygral 2010, in preparation) Here, we describe five simulations in which the initial ambient conditions are precisely the same, but the time histories of jet activity vary.…”

Section: Calculation Detailsmentioning

confidence: 99%

Three-Dimensional Simulations of Bi-Directed Magnetohydrodynamic Jets Interacting With Cluster Environments

O’Neill

Jones

2010

ApJ

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We report on a series of three-dimensional magnetohydrodynamic simulations of active galactic nucleus (AGN) jet propagation in realistic models of magnetized galaxy clusters. We are primarily interested in the details of energy transfer between jets and the intracluster medium (ICM) to help clarify what role such flows could have in the reheating of cluster cores. Our simulated jets feature a range of intermittency behaviors, including intermittent jets that periodically switch on and off and one model jet that shuts down completely, naturally creating a relic plume. The ICM into which these jets propagate incorporates tangled magnetic field geometries and density substructure designed to mimic some likely features of real galaxy clusters. We find that our jets are characteristically at least 60% efficient at transferring thermal energy to the ICM. Irreversible heat energy is not uniformly distributed, however, instead residing preferentially in regions very near the jet/cocoon boundaries. While intermittency affects the details of how, when, and where this energy is deposited, all of our models generically fail to heat the cluster cores uniformly. Both the detailed density structure and nominally weak magnetic fields in the ICM play interesting roles in perturbing the flows, particularly when the jets are non-steady. Still, this perturbation is never sufficient to isotropize the jet energy deposition, suggesting that some other ingredient is required for AGN jets to successfully reheat cluster cores.

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“…We can refer to it as the astrophysical limit. This approach is more application oriented [17,31,30,28,29,36,18] and does not aim at studying f…”

Section: Introductionmentioning

confidence: 99%

Glimm–Godunov’s method for cosmic-ray-hydrodynamics

Miniati

2007

Journal of Computational Physics

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A numerical method for integrating the equations describing a dynamically coupled system made of a fluid and cosmic-rays is developed. In smooth flows the effect of CR pressure is accounted for by modification of the characteristic equations and the energy exchange between cosmic-rays and the fluid, due to diffusive processes in configuration and momentum space, is modeled with a flux conserving method. Provided the shock acceleration efficiency as a function of the upstream conditions and shock Mach number, we show that the Riemann solver can be modified to take into account the cosmic-ray mediation without having to resolve the cosmic-ray induced substructure. Shocks are advanced with Glimm's method which preserves their discontinuous character without any smearing, thus allowing to maintain selfconsistency in the shock solutions. In smooth flows either Glimm's or a higher order Godunov's method can be applied, with the latter producing better results when approximations are introduced in the Riemann solver.

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Synthetic Observations of Simulated Radio Galaxies. I. Radio and X‐Ray Analysis

Cited by 37 publications

References 34 publications

Active galactic nuclei jets and multiple oblique shock acceleration: starved spectra

Active galactic nuclei jets and multiple oblique shock acceleration: starved spectra

Three-Dimensional Simulations of Bi-Directed Magnetohydrodynamic Jets Interacting With Cluster Environments

Glimm–Godunov’s method for cosmic-ray-hydrodynamics

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