Murchison Widefield Array and XMM-Newton observations of the Galactic supernova remnant G5.9+3.1

<jats:p><jats:italic>Aims.</jats:italic> In this paper we discuss the radio continuum and X-ray properties of the so-far poorly studied Galactic supernova remnant (SNR) G5.9 + 3.1.</jats:p> <jats:p><jats:italic>Methods.</jats:italic> We present the radio spectral energy distribution (SED) of the Galactic SNR G5.9 + 3.1 obtained with the <jats:italic>Murchison</jats:italic> Widefield Array (MWA). Combining these new observations with the surveys at other radio continuum frequencies, we discuss the integrated radio continuum spectrum of this particular remnant. We have also analyzed an archival <jats:italic>XMM-Newton</jats:italic> observation, which represents the first detection of X-ray emission from this remnant.</jats:p> <jats:p><jats:italic>Results.</jats:italic> The SNR SED is very well explained by a simple power-law relation. The synchrotron radio spectral index of G5.9 + 3.1 is estimated to be 0.42 ± 0.03 and the integrated flux density at 1 GHz to be around 2.7 Jy. Furthermore, we propose that the identified point radio source, located centrally inside the SNR shell, is most probably a compact remnant of the supernova explosion. The shell-like X-ray morphology of G5.9 + 3.1 as revealed by <jats:italic>XMM-Newton</jats:italic> broadly matches the spatial distribution of the radio emission, where the radio-bright eastern and western rims are also readily detected in the X-ray while the radio-weak northern and southern rims are weak or absent in the X-ray. Extracted MOS1+MOS2+PN spectra from the whole SNR as well as the north, east, and west rims of the SNR are fit successfully with an optically thin thermal plasma model in collisional ionization equilibrium with a column density <jats:italic>N</jats:italic><jats:sub><jats:italic>H</jats:italic></jats:sub> ~ 0.80 × 10<jats:sup>22</jats:sup> cm<jats:sup>−2</jats:sup> and fitted temperatures spanning the range <jats:italic>kT</jats:italic> ~ 0.14–0.23 keV for all of the regions. The derived electron number densi