The Hard X-ray Perspective on the Soft X-ray excess

The physical origin of the soft excess in AGN remains hotly debated. Blurredionised reflection, Comptonization, ionised absorption and other models canaccount for it, but 0.450keV observations are needed to break the degeneracybetween models. Our recent work shows that short, simultaneous snapshots withXMM and NuSTAR can distinguish between reflection and absorption using only thestrengths of the soft and hard excesses, without requiring more complex modelfits. We propose to observe 7 extreme AGN from the hard Xrayselected Swift/BATcatalogue jointly with XMM and NuSTAR in a 140 ks campaign. Our observationswill constrain the soft excess production mechanisms in these sources using anovel, powerful technique,shedding light on this longstanding question in AGN science. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]