Fig. 2.

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Broadband 0.3−195 keV spectrum of NGC 4258, composed of the 17 spectra analyzed in this work (12 XMM-Newton, 4 NuSTAR and 1 Swift/BAT) spanning more than 15 years of observations. While the soft emission ≲2 keV is due to extended plasma and is constant throughout the years, the harder component shows significant variability across different observations. In particular, NGC 4258 was caught in its faintest state during the NuSTAR observations. The spectral turnover below 4−5 keV is due to the moderate absorption, possibly due to the line of sight intercepting the warped maser disk.
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