[Paper Review] Multi-frequency observations of SNR J0453-6829 in the LMC; A composite supernova remnant with a pulsar wind nebula

F. Haberl, M. D. Filipović+8 more|MPG.PuRe (Max Planck Society)|Jun 25, 2012

Astrophysical Phenomena and Observations46 references7 citations

TL;DR

This study presents multi-frequency observations of SNR J0453–6829 in the Large Magellanic Cloud, confirming it as a composite supernova remnant hosting a pulsar wind nebula (PWN). Using new radio data from the Australia Telescope Compact Array and archival XMM-Newton X-ray observations, the authors determine a flat radio spectral index (α_core ≈ –0.04) for the PWN and a steeper index (α_shell ≈ –0.43) for the shell, with X-ray spectral analysis indicating a dynamical age of 12,000–15,000 years and a high swept-up mass of 830 M⊙, consistent with a well-evolved, radiative-phase remnant.

ABSTRACT

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. 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. 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. Our radio results confirm that this LMC SNR hosts a typical PWN. The prominent central core of the PWN exhibits a radio spectral index alpha_Core of -0.04+/-0.04, while in the rest of the SNR shell the spectral slope is somewhat steeper with alpha_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 x (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 12000-15000 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 solar masses, and an explosion energy of 7.6 x 10^50 erg. These parameters indicate a well evolved SNR with an X-ray spectrum dominated by emission from the swept-up material.

Motivation & Objective

• To investigate the multi-wavelength morphology and emission mechanisms in SNR J0453–6829, a bright X-ray and radio remnant in the Large Magellanic Cloud.
• To determine the nature of the central radio-bright core and confirm its identification as a pulsar wind nebula (PWN) through spectral and polarization analysis.
• To derive physical parameters such as shock temperature, dynamical age, electron density, and explosion energy using X-ray spectral fitting and the Sedov model.
• To assess the influence of the interstellar medium (ISM) on the remnant’s morphology, particularly in the southwest region with enhanced radio and Hα emission.
• To evaluate the supernova type and explosion history through X-ray abundance measurements and spectral modeling.

Proposed method

• Acquired new 6 cm and 3 cm radio-continuum observations using the Australia Telescope Compact Array (ATCA) at multiple frequencies.
• Analyzed archival XMM-Newton EPIC and RGS X-ray spectra to derive emission-line and continuum properties, including temperature and elemental abundances.
• Fitted X-ray spectra with thermal plasma models (e.g., APEC) and compared results with the Sedov model to estimate shock temperature, electron density, and explosion energy.
• Measured radio spectral indices (α = Sν ∝ να) across the remnant to distinguish between non-thermal (PWN) and thermal (shell) emission components.
• Performed polarization analysis at 6 cm and 3 cm to infer magnetic field structure and electron acceleration mechanisms in the radio-emitting regions.
• Correlated radio, optical (MCELS), and infrared (Spitzer) data to assess spatial relationships between emission features and ISM density variations.

Experimental results

Research questions

• RQ1 Is the central radio-bright core of SNR J0453–6829 consistent with a pulsar wind nebula (PWN), and what spectral and polarization properties support this?
• RQ2 What is the dynamical age of SNR J0453–6829, and how does it compare to other LMC supernova remnants in terms of evolution and energy dissipation?
• RQ3 What is the total mass swept up by the shock, and how does it relate to the remnant’s X-ray luminosity and shock temperature?
• RQ4 Why is the radio and Hα emission enhanced in the southwest rim, and what does this imply about the local ISM density and magnetic field structure?
• RQ5 To what extent are the X-ray abundances consistent with a core-collapse supernova, and how do they affect the interpretation of the remnant’s origin?

Key findings

• The central radio core exhibits a flat spectral index of α_core = –0.04 ± 0.04, characteristic of a pulsar wind nebula (PWN), confirming its non-thermal origin.
• The SNR shell has a steeper radio spectral index of α_shell = –0.43 ± 0.01, indicating non-thermal emission consistent with synchrotron radiation from relativistic electrons.
• The remnant has a nearly circular morphology of (31 ± 1) pc × (29 ± 1) pc, with a mean polarisation of 12% at 6 cm and 9% at 3 cm, suggesting ordered magnetic fields in the radio-emitting regions.
• X-ray spectral fitting yields a shock temperature of approximately 0.2 keV and a dynamical age of 12,000–15,000 years, placing the remnant in the late Sedov phase.
• Using the Sedov model, the electron density in the X-ray-emitting plasma is estimated at 1.56 cm⁻³, the swept-up mass is 830 M⊙, and the explosion energy is 7.6 × 10⁵⁰ erg.
• The X-ray spectrum is dominated by emission from swept-up ISM material, with Si overabundant and other elements consistent with or slightly below typical LMC abundances, indicating a core-collapse supernova origin.