Abstract
Supernova remnants are at the nexus of many important, comtemporary,
astrophysical problems: the late stage of stellar evolution, supernovae, the formation of compact objects, nucleosynthesis, collisionless shocks, particle acceleration and possibly gamma-ray bursts.
The major focus of this thesis is on the thermal X-ray emission. This is an important part of
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SNR studies as most of the initial mechanical energy is radiated as thermal X-ray emission.
The shocked environment and the interface between hot and cold gas give rise to X-ray plasma conditions unique to SNRs. Transient non-equilibrium ionisation (NEI) plasmas are expected to occur due to the low density and
corresponding long average collision time. They have been unambiguously detected in young SNRs. Among the most
conspicuous spectroscopic manifestations of NEI plasmas are emission from open-shell ionic species and spectral lines that arise from inner-shell excitation and ionisation. These features are marginal in ionisation equilibrium plasmas. High resolution and imaging spectroscopy, as highlighted in this thesis, are invaluable tools in unraveling SNR properties. Spatially resolved spectroscopy with high resolution and throughput, as is available with Chandra and XMM-Newton, also offers an opportunity to investigate a host of physical effects in greater detail than before.
The intrinsic brightness of the young Galactic SNR Cas A, coupled to the high sensitivity of the solid state (EPIC-MOS and EPIC-pn) X-ray camera's of XMM-Newton,make it possible to perform a detailed, spatially resolved, spectral analysisof the thermal emission of Cas A on a 20"x20" pixel scale.
The bandwidth (up to 15 keV) offers an unique opportunity toassess the origin of the hard X-ray continuum. Detailed electron temperature, ionisation age and Doppler maps of Cas A have been derived for the first time,
providing a wealth of information on the remnant's dynamics and details of the shock heating process. Observations with the Reflection Grating spectrometer (RGS) of SNR B0540-69.3, N 103B and DEM L71 in the Large Magellanic Cloud (LMC) are among the first highlyresolved X-ray spectra of SNRs. The capability of the RGS for highresolution spectroscopy of sources of moderate angular extent is well matched tothe typical angular sizes of SNRs in the LMC. The high dispersion of the RGSallows almost all of the X-ray spectral features emitted by these remnants to be
resolved. Detailed spectroscopic modeling permits independent measurements ofastrophysical quantities that affect line shape and production, such as electrontemperature, density and elemental abundance profiles.
Previous X-ray analysis of SNRs in the Small Magellanic cloud (SMC) have been limited to detections only, except for the bright IKT 22 (SNR 1E0102-72). The large bandwidth and sensitivity of XMM-Newton is a crucial aspect for a spectroscopic assesment of SNR properties in the SMC. We presented a synoptic study of 13 SNRs in the SMC.
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