LATE-TIME EVOLUTION OF COMPOSITE SUPERNOVA REMNANTS: DEEP<i>CHANDRA</i>OBSERVATIONS AND HYDRODYNAMICAL MODELING OF A CRUSHED PULSAR WIND NEBULA IN SNR G327.1-1.1

Abstract

In an effort to better understand the evolution of composite supernova\nremnants (SNRs) and the eventual fate of relativistic particles injected by\ntheir pulsars, we present a multifaceted investigation of the interaction\nbetween a pulsar wind nebula (PWN) and its host SNR G327.1-1.1. Our 350 ks\nChandra X-ray observations of SNR G327.1-1.1 reveal a highly complex\nmorphology; a cometary structure resembling a bow shock, prong-like features\nextending into large arcs in the SNR interior, and thermal emission from the\nSNR shell. Spectral analysis of the non-thermal emission offers clues about the\norigin of the PWN structures, while enhanced abundances in the PWN region\nprovide evidence for mixing of supernova ejecta with PWN material. The overall\nmorphology and spectral properties of the SNR suggest that the PWN has\nundergone an asymmetric interaction with the SNR reverse shock (RS) that can\noccur as a result of a density gradient in the ambient medium and/or a moving\npulsar that displaces the PWN from the center of the remnant. We present\nhydrodynamical simulations of G327.1-1.1 that show that its morphology and\nevolution can be described by a ~ 17,000 yr old composite SNR that expanded\ninto a density gradient with an orientation perpendicular to the pulsar's\nmotion. We also show that the RS/PWN interaction scenario can reproduce the\nbroadband spectrum of the PWN from radio to gamma-ray wavelengths. The analysis\nand modeling presented in this work have important implications for our general\nunderstanding of the structure and evolution of composite SNRs.\n