An X-ray characterization of the central region of the supernova remnant G332.5-5.6

¹ Instituto Argentino de Radioastronomía (CCT La Plata, CONICET), C.C.5, (1894) Villa Elisa, Buenos Aires, Argentina
e-mail: aesuarez@iar-conicet.gov.ar
² Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque, B1900FWA La Plata, Argentina
e-mail: jcombi@fcaglp.unlp.edu.ar
³ Dto de Investigación en Ciencias Exactas, Naturales e Ingeniería. Universidad Nacional de Rio Negro, Don Bosco y Leloir (CP 8500) Viedma, Argentina
e-mail: albacete.facundo@conicet.gov.ar
⁴ Instituto de Astronomía y Física del Espacio (IAFE), CC 67, Suc. 28, 1428 Buenos Aires, Argentina
⁵ INAF–Observatorio Astronomico di Palermo, P.za del Parlamento 1, 90134 Palermo, Italy

Received: 8 June 2015
Accepted: 1 September 2015

Abstract

Aims. We present an X-ray analysis of the central region of supernova remnant (SNR) G332.5−5.6 through an exhaustive analysis of XMM-Netwon observations with complementary infrared observations. We characterize and discuss the origin of the observed X-ray morphology, which presents a peculiar plane edge over the west side of the central region.

Methods. The morphology and spectral properties of the X-ray SNR were studied using a single full frame XMM-Newton observation in the 0.3 to 10.0 keV energy band. Archival infrared WISE observations at 8, 12 and 24 μm were also used to investigate the properties of the source and its surroundings at different wavelengths.

Results. The results show that the extended X-ray emission is predominantly soft (0.3−1.2 keV) and peaks around 0.5 keV, which shows that it is an extremely soft SNR. X-ray emission correlates very well with central regions of bright radio emission. On the west side the radio/X-ray emission displays a plane-like feature with a terminal wall where strong infrared emission is detected. Our spatially resolved X-ray spectral analysis confirms that the emission is dominated by weak atomic emission lines of N, O, Ne, and Fe, all of them undetected in previous X-ray studies. These characteristics suggest that the X-ray emission is originated in an optically thin thermal plasma, whose radiation is well fitted by a non-equilibrium ionization collisional plasma (VNEI) X-ray emission model. Our study favors a scenario where G332.5-5.6 is expanding in a medium with an abrupt density change (the wall), likely a dense infrared emitting region of dust on the western side of the source.