2011MNRAS.412..401B

We study X-ray to K-band luminosity ratios (L_X/L_K) of late-type galaxies in the 0.3-0.7 keV energy range. From the Chandra archive, we selected nine spiral and three irregular galaxies with point source detection sensitivity better than 5 {x} 10³⁶ erg/s in order to minimize the contribution of unresolved X-ray binaries. In late-type galaxies cold gas and dust may cause significant interstellar absorption, therefore we also demanded the existence of publicly available H I maps. The obtained L_X/L_K ratios vary between (5.4 and 68) {x} 10²⁷ erg/s/L_K,☉ exceeding by factors of 2-20 the values obtained for gas-poor early-type galaxies. Based on these results we constrain the role of supersoft X-ray sources as progenitors of Type Ia supernovae (SNe Ia). For the majority of galaxies the upper limits range from ∼ 3 to ∼15 per cent of the SN Ia frequency inferred from K-band luminosity, but for a few of them no meaningful constraints can be placed. On a more detailed level, we study individual structural components of spiral galaxies: bulge and disc, and, for grand design spiral galaxies, arm and interarm regions.