EDP Sciences
Free access
Issue
A&A
Volume 420, Number 3, June IV 2004
Page(s) 937 - 944
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:20035700


A&A 420, 937-944 (2004)
DOI: 10.1051/0004-6361:20035700

An evolutionary model for pulsar-driven supernova remnants

A hydrodynamical model
E. van der Swaluw1, 2, T. P. Downes3 and R. Keegan3

1  Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland
2  FOM-Institute for Plasma Physics Rijnhuizen, PO Box 1207, 3430 BE Nieuwegein, The Netherlands
3  School of Mathematical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland

(Received 17 November 2003 / Accepted 8 March 2004)

Abstract
We present a model of a pulsar wind nebula evolving inside its associated supernova remnant. The model uses a hydrodynamics code to simulate the evolution of this system when the pulsar has a high velocity. The simulation distinguishes four different stages of pulsar wind nebula evolution: the supersonic expansion stage, the reverse shock interaction stage, the subsonic expansion stage and ultimately the bow shock stage. The simulation bears out that, due to the high velocity of the pulsar, the position of the pulsar is off-centered with respect to its pulsar wind nebula, after the passage of the reverse shock. Subsequently the pulsar wind nebula expands subsonically until the event of the bow shock formation, when the motion of the pulsar becomes supersonic. The bow shock formation event occurs at roughly half the crossing time, when the pulsar is positioned at 0.677 times the radius of the supernova remnant blastwave, in complete agreement with analytical predictions. The crossing time is defined by the age of the supernova remnant when the pulsar overtakes the blastwave bounding the supernova remnant.

The results of the model are applied to three supernova remnants: N157B, G327.1-1.1 and W44. We argue that the head of the pulsar wind nebula, containing the active pulsar, inside the first two systems is not bounded by a bow shock. However, in the case of W44 we argue for a scenario in which the pulsar wind nebula is bounded by a bow shock, due to the supersonic motion of the pulsar.


Key words: pulsars: general -- stars: supernova remnants -- shocks waves -- hydrodynamics

Offprint request: E. van der Swaluw, swaluw@rijnh.nl

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