Fe K alpha line from the Broad Line Region of PDS456 with XRISM/Resolve

The high-luminosity, high-mass and likely super-Eddington quasar PDS 456 is known for its extremely dynamic environment. A wealth of observational features from the millimetric up to the X-ray band shows energetic outflows at all scales, from accretion disc up to galaxy scales. Broad Emission Lines in the optical and UV show significant widths and line-of-sight velocities. Moreover, NIR interferometry revealed a partially outflowing Broad Line Region. Thanks to the unprecedented energy resolution of the X-ray microcalorimeter Resolve onboard XRISM, we detect a neutral Fe K alpha line, the main tracer of cold matter around AGNs. The line blueshift (v out=2700 km s-1) and width (sigma at most 700 km s-1) are on the lower bound of the range of values of the optical-UV emission lines, possibly suggesting a stratified medium. The derived column density, N H about 10 22 cm-2, is significantly lower than what expected for Broad Line Regions, again in agreement with a composite emission. The very small Equivalent Width (9 eV) marks one of the smallest measurements in the literature and probes the high-luminosity end of the so-called Iwasawa-Taniguchi (or X-ray Baldwin) effect.