What is the origin of the soft excess in AGN

We investigate the nature of the soft excess below 1 keV observed in AGN. We use the XMM‐Newton data of the low redshift, optically bright quasar, PG 1211+143, and we compare it with the Narrow Line Seyfert 1 galaxy, 1H 0707‐495, which has one of the strongest soft excesses seen. We test various ideas for the origin of the soft X‐ray excess, including a separate spectral component (for example a low temperature Comptonized component), a reflection‐dominated model, or a complex absorption model. All three can give good fits to the data, and χ2 fitting criteria are not sufficient to discriminate among them. Instead, we favor the complex absorption model on the grounds that it is the most physically plausible.