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Nonlinear waves in Poynting-flux dominated outflows

Mochol, Iwona

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Abstract

Rotating, compact objects power some of the most spectacular phenomena in astrophysics, e.g., gamma-ray bursts, active galactic nuclei and pulsar winds. The energy is carried by Poynting flux, and the system is usually modelled using relativistic magnetohydrodynamics (MHD). However, in the relatively low density medium expected around some of these objects, the MHD approximation breaks down, allowing new, large-amplitude waves to propagate. We discuss the role of these waves in two astrophysical contexts:

In blazar jets, we show that a magnetic shear, launched together with a plasma from the black hole magnetosphere, begins to accelerate particles at a large distance from its source. The resulting non-thermal emission can, nevertheless, be modulated on very short timescales, which can explain the rapid variability of the TeV gamma-ray flux observed from some blazars.

In pulsar winds, we analyze the radial propagation of superluminal modes, including their damping by radiation reaction and by interaction with an external photon field. We discuss their effect on the structure of the pulsar wind termination shock, presenting new solutions in which the nonlinear wave is asymptotically matched to the constant pressure surroundings. The observational implications of these solutions are discussed for both isolated pulsars, and pulsars in binary systems.

Dokumententyp: Dissertation
Erstgutachter: Kirk, Prof. Dr. John G.
Tag der Prüfung: 7 November 2012
Erstellungsdatum: 28 Nov. 2012 09:28
Erscheinungsjahr: 22 November 2012
Institute/Einrichtungen: Fakultät für Physik und Astronomie > Dekanat der Fakultät für Physik und Astronomie
DDC-Sachgruppe: 500 Naturwissenschaften und Mathematik
520 Astronomie
530 Physik
Normierte Schlagwörter: Nichtlineare Welle, Elektromagnetische Welle, Plasmadynamik, Magnetohydrodynamische Welle, Jet <Astronomie>, Pulsar, Blazar, Schwarzes Loch, Photon-Drag-Effekt
Freie Schlagwörter: nonlinear waves, pulsar wind, termination shock, charge starvation, underdense plasma, radiation reaction, blazar jet, magnetosphere
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