Two evolved supernova remnants with newly identified Fe-rich cores in the Large Magellanic Cloud

P. J. Kavanagh (1) , M. Sasaki (1) , L. M. Bozzetto (2) , S. D. Points (3) , E. J. Crawford (2) , J. Dickel (4) , M. D. Filipović (2) , F. Haberl (5) , P. Maggi (6) , E. T. Whelan (1)

1 IAAT - Institut für Astronomie und Astrophysik [Tübingen]
2 Western Sydney University
3 Cerro Tololo Inter-American Observatory
4 The University of New Mexico [Albuquerque]
5 MPE - Max-Planck-Institut für Extraterrestrische Physik
6 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation

Aims. We present a multi-wavelength analysis of the evolved supernova remnants MCSNR J0506−7025 and MCSNR J0527−7104 in the Large Magellanic Cloud.Methods. We used observational data from XMM-Newton, the Australian Telescope Compact Array, and the Magellanic Cloud Emission Line Survey to study their broad-band emission and used Spitzer and H i data to gain a picture of the environment into which the remnants are expanding. We performed a multi-wavelength morphological study and detailed radio and X-ray spectral analyses to determine their physical characteristics.Results. Both remnants were found to have bright X-ray cores, dominated by Fe L-shell emission, which is consistent with reverse shock-heated ejecta with determined Fe masses in agreement with Type Ia explosion yields. A soft X-ray shell, which is consistent with swept-up interstellar medium, was observed in MCSNR J0506−7025, suggestive of a remnant in the Sedov phase. Using the spectral fit results and the Sedov self-similar solution, we estimated the age of MCSNR J0506−7025 to be ~16−28 kyr, with an initial explosion energy of (0.07−0.84) × 1051 erg. A soft shell was absent in MCSNR J0527−7104, with only ejecta emission visible in an extremely elongated morphology that extends beyond the optical shell. We suggest that the blast wave has broken out into a low density cavity, allowing the shock heated ejecta to escape. We find that the radio spectral index of MCSNR J0506−7025 is consistent with the standard −0.5 for supernova remnants. Radio polarisation at 6 cm indicates a higher degree of polarisation along the western front and at the eastern knot with a mean fractional polarisation across the remnant of P ≅ (20 ± 6)%. Conclusions. The detection of Fe-rich ejecta in the remnants suggests that both resulted from Type Ia explosions. The newly identified Fe-rich cores in MCSNR J0506−7025 and MCSNR J0527−7104 make them members of the expanding class of evolved Fe-rich remnants in the Magellanic Clouds.

Mots clés: ISM: supernova remnants; Magellanic Clouds; X-rays: ISM

Domaines: Astrophysique [astro-ph]

P. J. Kavanagh, M. Sasaki, L. M. Bozzetto, S. D. Points, E. J. Crawford, et al.. Two evolved supernova remnants with newly identified Fe-rich cores in the Large Magellanic Cloud. Astronomy and Astrophysics - A&A, 2016, 586, pp.A4. ⟨10.1051/0004-6361/201527414⟩. ⟨cea-01430172⟩