The origin of the X-ray emission from the non-starburst gas-rich luminous infrared galaxies Arp 302

We present an analysis of the XMM-Newton observation of luminous infrared merging galaxies Arp 302 and a joint re-analysis of its Chandra observation. In particular, we focus on the more significant X-ray emitter of the pair, Arp 302N. Chandra detects significant soft X-ray emission from the hot gas in the star-forming region of Arp 302N spreading up to 12 kpc. We estimate the star formation rate of Arp 302N to be around 1-2 M-circle dot yr(-1) based on the X-ray luminosity of the star-forming region, similar to previous measurements at longer wavelengths. Chandra and XMM-Newton observations show evidence of a Si xiii emission line with 86 per cent confidence. Our best-fitting model infers a super-solar silicon abundance in the star-forming region, likely related to the past core-collapse supernovae in this galaxy. Similar silicon overabundance was reported in the circumstellar medium of core-collapse supernova remnants in our Galaxy. We also detect narrow Fe K alpha and Fe K beta (98.6 per cent confidence) emission lines as part of the active galactic nucleus (AGN) emission. Our best-fitting spectral model using mytorus indicates the evidence of a heavily obscured power-law emission with N-H > 3 x 10(24) cm(-2) in addition to a weak, unobscured power-law emission. The scattering fraction of the unobscured power-law emission from Compton-thin materials is 0.7 per cent. All these spectral features suggest evidence of a Seyfert 2-like AGN in Arp 302N. The X-ray measurement of its AGN activity is consistent with the previous Spitzer measurement of the same object.