SIMBAD references

The intensely varying Active Galactic nucleus (AGN) NGC 2992, on timescales of days to years, provides us with a unique testbed to study the response of the narrow FeKα emission line to the changes in the primary 2-10 keV AGN continuum. We find a strong correlation between the narrow FeKα line flux and the 2-10 keV flux with a Spearman correlation coefficient s = 0.70 and probability p < 0.001, over a period of ∼20 yr. There is no evidence of such a correlation in <1 yr, but the FeKα flux responds at ∼3 yr timescales, allowing us to put the reprocessor distance scale to 0.3 pc ≤ d ≤ 1 pc, consistent with that of torus reflection. The primary 2-10 keV continuum of NGC 2992 undergoes a high-low-high transition in ∼16 yr (2003-2019). Future long term monitoring will be crucial.