  We have investigated three SNRs in the LMC using multi-wavelength data. These
SNRs are generally fainter than the known sample and may represent a previously
missed population. One of our SNRs is the second LMC remnant analyzed which is
larger than any Galactic remnant for which a definite size has been
established. The analysis of such a large remnant contributes to the
understanding of the population of highly evolved SNRs. We have obtained X-ray
images and spectra of three of these recently identified SNRs using the
XMM-Newton observatory. These data, in conjunction with pre-existing optical
emission-line images and spectra, were used to determine the physical
conditions of the optical- and X-ray-emitting gas in the SNRs. We have compared
the morphologies of the SNRs in the different wavebands. The physical
properties of the warm ionized shell were determined from the H-alpha surface
brightness and the SNR expansion velocity. The X-ray spectra were fit with a
thermal plasma model and the physical conditions of the hot gas were derived
from the model fits. Finally, we have compared our observations with
simulations of SNR evolution.
