Four new X-ray-selected supernova remnants in the Large Magellanic Cloud

Abstract

Aims. We present a detailed multi-wavelength study of four new supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). The objects were identified as SNR candidates in X-ray observations performed during the survey of the LMC with XMM-Newton. Methods. Data obained with XMM-Newton are used to investigate the morphological and spectral features of the remnants in X-rays. We measure the plasma conditions, look for supernova (SN) ejecta emission, and constrain some of the SNR properties (e.g. age and ambient density). We supplement the X-ray data with optical, infrared, and radio-continuum archival observations, which allow us to understand the conditions resulting in the current appearance of the remnants. Based on the spatially-resolved star formation history (SFH) of the LMC together with the X-ray spectra, we attempt to type the supernovae that created the remnants. Results. We confirm all four objects as SNRs, to which we assign the names MCSNR J0508−6830, MCSNR J0511−6759, MCSNR J0514−6840, and MCSNR J0517−6759. In the first two remnants, an X-ray bright plasma is surrounded by very faint [S ii] emission. The emission from the central plasma is dominated by Fe L-shell lines, and the derived iron abundance is greatly in excess of solar. This establishes their type Ia (i.e. thermonuclear) SN origin. They appear to be more evolved versions of other Magellanic Cloud iron-rich SNRs which are centrally-peaked in X-rays. From the two other remnants (MCSNR J0514−6840 and MCSNR J0517−6759), we do not see ejecta emission. At all wavelengths at which they are detected, the local environment plays a key role in their observational appearance. We present evidence that MCSNR J0517−6759 is close to and interacting with a molecular cloud, suggesting a massive progenitor.

The population of X-ray supernova remnants in the Large Magellanic Cloud

“…The shell A of DEM L316 (MCSNR J0547−6941) has striking spectral differences to the very close neighbour MCSNR J0547−6943 (DEM L316B): the former is also mostly exhibiting Fe L-shell emission, which leads to the interpretation that it is another type Ia remnant (Nishiuchi et al 2001;. Then come three more evolved (age 15 kyr) iron-rich SNRs that were presented in Maggi et al (2014) and Bozzetto et al (2014). Finally, since these publications, we obtained XMM-Newton follow-up observations of two remnants, which we classified as type Ia: i) MCSNR J0506−7026 was a ROSATselected candidate ([HP99] 1139), which revealed a remnant similar to DEM L238 and L249, about 17−21 kyr old and holding about 0.9 M −1 M in the central region (Kavanagh et al, in prep., Table E.1); ii) MCSNR J0527−7104 was confirmed by our group in a multi-wavelength study (Kavanagh et al 2013).…”

Multi-frequency study of the newly confirmed supernova remnant MCSNR J0512−6707 in the Large Magellanic Cloud

“…Detailed descriptions of the X-ray background constituents and spectral modelling can be found in Bozzetto et al (2014) and Maggi et al (2014). Here we briefly summarise the treatment of the X-ray background in the case of MCSNR J0512−6707.…”

Radio-continuum study of MCSNR J0536–7038 (DEM L249)

“…The Large Magellanic Cloud (LMC) is a favourable environment for observing supernova remnants (SNRs), due to the relatively close proximity in which it is located (and in turn larger angular size), making it possible to resolve these objects (as 1 pc = 4 ′′ ). One LMC SNR of particular interest is MCSNR J0536-7038, a Type Ia SNR that has prominent Fe emission in its core and is thought to be the result of a 'prompt' Type Ia event (Borkowski, Hendrick, & Reynolds 2006;Maggi et al 2014). MCSNR J0536-7038 was originally observed by Davies et al (1976) using the 48-in SRC Schimdt camera, who gave this object the association DEM L249.…”