The first broadband X-ray view of the narrow line Seyfert 1 Ton S180
  We present joint \textit{XMM-Newton} and \textit{NuSTAR} observations of the
`bare' narrow line Seyfert 1 Ton S180 ($z=0.062$), carried out in 2016 and
providing the first hard X-ray view of this luminous galaxy. We find that the
0.4--30 keV band cannot be self-consistently reproduced by relativistic
reflection models, which fail to account simultaneously for the soft and hard
X-ray emission. The smooth soft excess prefers extreme blurring parameters,
confirmed by the nearly featureless nature of the RGS spectrum, while the
moderately broad Fe K line and the modest hard excess above 10 keV appear to
arise in a milder gravity regime. By allowing a different origin of the soft
excess, the broadband X-ray spectrum and overall spectral energy distribution
(SED) are well explained by a combination of: (a) direct thermal emission from
the accretion disc, dominating from the optical to the far/extreme UV; (b)
Comptonization of seed disc photons by a warm ($kT_{\rm e}\sim0.3$ keV) and
optically thick ($\tau\sim10$) corona, mostly contributing to the soft X-rays;
(c) Comptonization by a standard hot ($kT_{\rm e} \gtrsim 100$ keV) and
optically thin ($\tau<0.5$) corona, responsible for the primary X-ray
continuum; and (d) reflection from the mid/outer part of the disc. The two
coronae are suggested to be rather compact, with $R_{\rm hot} \lesssim R_{\rm
warm} \lesssim 10$ R$_{\rm g}$. Our SED analysis implies that Ton S180 accretes
at super-Eddington rates. This is a key condition for the launch of a wind,
marginal (i.e., 3.1$\sigma$ significance) evidence of which is indeed found in
the RGS spectrum.
