Tracking the Iron K$\alpha$ line and the Ultra Fast Outflow in NGC 2992 at different accretion states

TL;DR

This study investigates the behavior of the Iron Kα line and ultra-fast outflows in NGC 2992 across different accretion states, revealing variable outflows and complex emission components linked to the galaxy's accretion activity.

Contribution

It provides new evidence of an ultra-fast outflow at 0.21c and characterizes the multi-component Iron Kα emission in NGC 2992, linking outflow properties to accretion rates.

Findings

Detection of an ultra-fast outflow at 0.21c with 99% confidence.

Identification of three distinct Iron Kα emission components.

Correlation between outflow ejection and accretion rate exceeding 2% of Eddington.

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$\times10^{-11}$ erg cm$^{-2}$ s$^{-1}$) but NuSTAR showed an increase in the 2-10 keV flux up to 6$\times10^{-11}$ erg cm$^{-2}$ s$^{-1}$. We find possible evidence of an Ultra Fast Outflow with velocity $v_1=0.21\pm0.01c$ (detected at about 99% 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% of the Eddington luminosity. The analysis of the low flux 2010/2013 XMM data allowed us to determine that the Iron K$\alpha$ 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 disk, which has been detected only in the 2003 XMM observation.