Tracking the iron K α line and the ultra fast outflow in NGC 2992 at different accretion states

Abstract

The Seyfert 2 galaxy NGC 2992 has been monitored eight times by XMM-Newton in 2010 and then observed again in 2013, while in 2015 it was simultaneously targeted by Swift and NuSTAR. XMM-Newton always caught the source in a faint state (2-10 keV fluxes ranging from 0.3 to 1.6 × 10^-11 erg cm^-2 s^-1), but NuSTAR showed an increase in the 2-10 keV flux up to 6 × 10^-11 erg cm^-2 s^-1. We find possible evidence of an Ultra Fast Outflow with velocity v₁ = 0.21 ± 0.01c (detected at about 99 per cent confidence level) in such a flux state. The UFO in NGC 2992 is consistent with being ejected at a few tens of gravitational radii only at accretion rates greater than 2 per cent of the Eddington luminosity. The analysis of the low-flux 2010/2013 XMM data allowed us to determine that the Iron K α emission line complex in this object is likely the sum of three distinct components: a constant, narrow one due to reflection from cold, distant material (likely the molecular torus); a narrow, but variable one which is more intense in brighter observations and a broad relativistic one emitted in the innermost regions of the accretion disc, which has been detected only in the 2003 XMM observation.