Multi-frequency observations of SNR J0453-6829 in the LMC. A composite supernova remnant with a pulsar wind nebula

Context. The Large Magellanic Cloud (LMC) is rich in supernova remnants (SNRs), which can be investigated in detail with radio, optical, and X-ray observations. SNR J0453-6829 is an X-ray and radio-bright remnant in the LMC, within which previous studies revealed the presence of a pulsar wind nebula (PWN), making it one of the most interesting SNRs in the Local Group of galaxies.
Aims: We study the emission of SNR J0453-6829 to improve our understanding of its morphology, spectrum, and thus the emission mechanisms in the shell and the PWN of the remnant.
Methods: We obtained new radio data with the Australia Telescope Compact Array and analysed archival XMM-Newton observations of SNR J0453-6829. We studied the morphology of SNR J0453-6829 from radio, optical, and X-ray images and investigated the energy spectra in the different parts of the remnant.
Results: Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index α_Core of -0.04 ± 0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with α_Shell = -0.43 ± 0.01. We detect regions with a mean polarisation of P ≅ (12 ± 4)% at 6 cm and (9 ± 2)% at 3 cm. The full remnant is of roughly circular shape with dimensions of (31 ± 1) pc × (29 ± 1) pc. The spectral analysis of the XMM-Newton EPIC and RGS spectra allowed us to derive physical parameters for the SNR. Somewhat depending on the spectral model, we obtain for the remnant a shock temperature of around 0.2 keV and estimate the dynamical age to 12 000-15 000 years. Using a Sedov model we further derive an electron density in the X-ray emitting material of 1.56 cm^-3, typical for LMC remnants, a large swept-up mass of 830 M_⊙, and an explosion energy of 7.6 × 10⁵⁰ erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material.