Is the Duck an Interacting Composite?

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Session 83 -- Supernova Remnants
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[83.05] Is the Duck an Interacting Composite?

K.W. Weiler (NRL), N.E. Kassim (NRL), D.A. Frail (NRAO)

The supernova remnant G5.4$-$1.2 and the 15,000 year old pulsar PSR1757$-$24 are thought to be physically associated but the (implied) transverse motion in order for the pulsar to have been born at the geometric center of the remnant is excessively large (2500 km s$^{-1}$), raising doubts about the association. We present new radio observations made at the VLA in the continuum at 327 MHz and the HI line at 1420 MHz to address this issue. All available data support the association.

Perhaps the most important evidence that this is a true pulsar-supernova remnant association comes from the radio spectral index distribution (between 327 MHz and 1420 MHz) across the bright western side of the remnant. We see a steepening in the spectral index away from the point where pulsar is thought to have penetrated the shell. The simpliest interpretation is that the energetic pulsar and its surrounding wind nebula have overtaken the supernova remnant shell and ``rejevenated'' its radio emision. If verified, this would be an example of a new class of ``interacting composite'' remnants, in which the pulsar exerts a dominant influence on the energetics and dynamics of the supernova remnant shell.

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