Dynamical models for jet deceleration in the radio galaxy 3C 31

By R. Laing, A. Bridle. 2002

173 citations recorded by the source corpus.

We present a dynamical analysis of the flow in the jets of the low-luminosity radio galaxy 3C31 based on our earlier geometrical and kinematic model (Laing & Bridle 2002) and on estimates of the external pressure and density distributions from Chandra observations (Hardcastle et al. 2002). We apply conservation of particles, energy and momentum to derive the variations of pressure and density along the jets and show that there are self-consistent solutions for deceleration by injection of thermal matter. We initially take the jets to be in pressure equilibrium with the external medium at large distances from the nucleus and the momentum flux to be � = �/c, where � is the energy flux; we then progressively relax these constraints. With our initial assumptions, the energy flux is well determined: � � 9 – 14 ×10 36 W. We infer that the jets are over-pressured compared with the external medium at the flaring point (1.1kpc from the nucleus) where they start to expand rapidly. Local minima in the density and pressure and maxima in the mass injection rate and Mach number occur at � 3kpc. Further out, the jets decelerate smoothly with a Mach number � 1. The mass injection rate we infer is comparable with that expected from stellar mass loss throughout the cross-section of the jet close to the flaring point, but significantly exceeds it at large distances. We conclude that entrainment from the galactic atmosphere across the turbulent boundary layer of the jet is the dominant mass input process far from the nucleus, but that stellar mass loss may also contribute near the flaring point. The occurrence of a significant over-pressure at the flaring point leads us to suggest that it is the site of a stationary shock system, perhaps caused by reconfinement of an initially free jet. Our results are compatible with a jet consisting of e e + plasma on parsec scales which picks up thermal matter from stellar mass loss to reach the inferred density and mass flux at the flaring point, but we cannot rule out an e p + composition with a low-energy cut-off.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/67840264f9f91e7bedba9347bd285c45ab803829

How researchers see this paper

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In Astronomy and Astrophysics

1. Judith Croston
2. M. Hardcastle
3. C. Jones
4. D. Harris
5. W. Forman
6. A. Tchekhovskoy
7. D. Evans
8. O. Bromberg

In Nuclear and High Energy Physics

1. M. Hardcastle
2. Judith Croston
3. D. Harris
4. D. Evans
5. A. Tchekhovskoy
6. M. Birkinshaw
7. O. Bromberg
8. A. Bridle

Citations in the corpus

• Radiative Shock-induced Collapse of Intergalactic Clouds (2003, methodology): “We, therefore, used the detailed radio and X-ray study of the prototypical FRI-type radio galaxy 3C31 by Laing & Bridle (2002) to estimate plausible jet parameters near Minkowski’s Object, at ∼ 15 kpc from the NGC 541 AGN.”
• X-Ray Emission from the Hot Interstellar Medium and Southwest Radio Lobe of the Nearby Radio Galaxy Centaurus A (2003, background): “The jet/ lobe morphology of Cen A is clearly different than the ‘‘ tailed twin-jet ’’ morphology (Leahy 1993) commonly associated with objects like 3C 31 (Hardcastle et al. 2002b; Laing & Bridle 2002a, 2002b) and 3C 449 (Feretti et al. 1999).”
• X-Ray Emission from Extragalactic Jets (2006, background): “…circumstantial evidence for acceleration of jet features on pc-scales (e.g. Hardee, Walker & Gómez 2005) and it is generally accepted that both FRI (Laing & Bridle 2002a) and quasar (Wardle & Aaron 1997) jets decelerate on pc to kpc scales there is no indication that significant jet acceleration…”
• A Chandra observation of the X-ray environment and jet of 3C 296 (2002, methodology): “3 and is associated with the well-collimated inner region defined by Laing & Bridle (2002a).”
• Three-dimensional relativistic MHD simulations of active galactic nuclei jets: magnetic kink instability and Fanaroff–Riley dichotomy (2015, background): “Some jets appear conical, show large-scale wiggles, decelerate due to the interaction with the ambient medium (Laing 1993; Laing & Bridle 2002), like the M87 jet (Hines, Eilek, & Owen 1989).”
• Radio and X-Ray Observations of the Jet in Centaurus A (2003, methodology): “On the other hand, there is no particular reason to believe that theenergy density in the jet is the minimum energy, and some evidence that it is greater for FRI jets (e.g., Laing & Bridle 2002b) which would increase the required mass.”
• Radio galaxies and feedback from AGN jets (2020, background): “nal shock), while the centre-brightened FRIs are known to have initially relativistic jets that decelerate on kpc scales (e.g., Bicknell, 1995; Laing and Bridle, 2002; Tchekhovskoy and Bromberg, 2016).”
• Dynamics and high-energy emission of the flaring HST-1 knot in the M 87 jet (2006, background): “Previously, reconfinement shocks in FR I jets were proposed to be placed at much larger distances from the central engines, namely at the position of the brightest knots ∼1 kpc from active nuclei (Laing & Bridle 2002).3 In the case of the M 87 jet, it would be then at knot A (Falle & Wilson 1985).”
• Hot and cold gas accretion and feedback in radio-loud active galaxies (2007, methodology): “For 3C 31 Laing & Bridle (2002b) quote a jet powerQ ≈ 1037 W.”