XMM-Newton and NuSTAR spectra and continuum models and their residuals. a: background subtracted XMM-Newton (pn in black, MOS1+2 in red) and NuSTAR (FPMA+B in blue) spectra, and their corresponding background levels (gray, orange, and violet, respectively) are shown with the baseline continuum model (see Sect. 4.1). The MOS1 and 2 and FPM-A and -B spectra have been merged for plotting purposes. b: residuals (data-model/error), with respect to the baseline continuum model. In green, we highlight the energy ranges where the most prominent positive and negative residuals are found (see Sect. 4.2). c: residuals after including three emissions and three absorption Gaussian features (see Sect. 5). d: residuals after including two XSTAR tables to model the soft and hard band absorption features (see Sect. 6.1).