NGC 2992 has been observed at different flux levels (e.g. Fig. 14) and in Marinucci et al. (2018) a detailed analysis of XMM–Newton exposures of this object is presented. In order to provide an holistic view of the spectral properties of the central engine in NGC 2992, we tested our 2019 best-fitting model (model 1 presented in Section 4.3) on the exposures where the source was found in its lowest and highest states. In particular, we considered the XMM–Newton archival observations taken on 2003-05-19 and 2010-11-28 (Obs.IDs. 01479203014 and 0654910901, respectively). We thus reproduced them directly adopting the best-fitting model found for orbit 2 and show it in Fig. 12. We accounted for the different flux states computing the normalization of the primary emission, its associated reflected component, and the one of the apec and Cloudy tables. All the other parameters have been kept fixed to their corresponding best-fitting values already quoted in Table 5. Moreover, to account for the broad emission line found required by the 2003 data, we added a Gaussian component whose width was kept fixed to σ = 400 eV, in accordance with what literature papers (e.g. Nandra et al. 1997; Shu et al. 2010). This basic procedure led us to the fits shown in Fig. 15, with statistics of χ2/d.o.f. = 218/170 and χ2/d.o.f. = 181/140. In the high flux level, (F2–10 keV = (9.5 ± 0.1) × 10−11 erg cm−2 s−1), the normalization of the power law is Normpo = (3.00 ± 0.01) × 10−2 ph. keV−1 cm2 s−1, about twice of what found in 2019 while the amount of reflected flux is fully consistent with what found in 2019 as we obtained NormMyTorus = (9.7 ± 3.7) × 10−2 ph. keV−1 cm2 s−1. On the other hand, in the 2010 low flux level exposure (F2–10 keV  = (2.9 ± 0.2) × 10−12 erg cm−2 s−1), we found the power-law normalization to be Normpo = (4.7 ± 0.2) × 10−4 ph. keV−1 cm2 s−1 about 20–30 times lower than in 2019. The normalization of the reflected component modelled using MyTorus is NormMyTorus = (9.5 ± 1.2) × 10−3 ph. keV−1 $\rm cm^{2}$ s−1, a factor of ∼10 less than in 2019. Therefore, on very long time-scales and during a prolonged low state of the source in 2010, the strength of the reflector appears to respond to the continuum. However, the smaller value of the reflected component found in 2010 can be explained by the torus reflecting the primary continuum of NGC 2992 during a low flux state. Observing the light curves in Fig. 1, before 2010 NGC 2992 was observed in a very low flux state, even lower than the one in 2021. Such a long-term adjustment suggests that reflected spectrum emerges far from the central engine. Finally, in accordance with previous studies, the Fe Kα emission line of NGC 2992 has an unresolved component correlating with the primary flux and emerging from the broad line region. However, the current MyTorus-based model accounts for whole Fe Kα flux (see residuals in Fig. 15) and data do not require any additional Gaussian component. Below 1 keV, the non-variable behaviour of the distant scattering off the NLR can be witnessed in the top panels of Fig. 7 or in the first bin of the excess variance spectra in both Figs 6 and  8.
Citation: Nandra et al. 1997
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