The Low-temperature Corona in ESO 511−G030 Revealed by NuSTAR and XMM-Newton

We present the results from a coordinated XMM-Newton + NuSTAR observation of the Seyfert 1 galaxy ESO 511−G030. With this joint monitoring program, we conduct a detailed variability and spectral analysis. The source remained in a low flux and very stable state throughout the observation period, although there are slight fluctuations of flux over long timescales. The broadband (0.3–78 keV) spectrum shows the presence of a power-law continuum with a soft excess below 2 keV, a relatively narrow iron K α emission (∼6.4 keV), and an obvious cutoff at high energies. We find that the soft excess can be modeled by two different possible scenarios: a warm ( kT _e ∼ 0.19 keV) and optically thick ( τ = 18–25) Comptonizing corona or a relativistic reflection from a high-density ( $\mathrm{log}[{n}_{{\rm{e}}}/{\mathrm{cm}}^{-3}]=17.1\mbox{--}18.5$ ) inner disk. All models require a low temperature ( kT _e ∼ 13 keV) for the hot corona.