NGC 2992 in an X-ray high state observed by XMM: Response of the Relativistic Fe K$\alpha$ Line to the Continuum

TL;DR

This paper reports on an XMM observation of NGC 2992 during its highest X-ray activity, revealing a relativistic Fe Kα line that responds to continuum changes, indicating inner accretion disk activity.

Contribution

It provides the first detailed analysis of the relativistic Fe Kα line response to X-ray flux in NGC 2992 during a high activity state.

Findings

Relativistic Fe Kα line flux increased with X-ray continuum.

X-ray activity was the highest ever detected for NGC 2992.

The Fe Kα line responds to continuum variability, indicating inner disk origin.

Abstract

We present the analysis of an XMM observation of the Seyfert galaxy NGC 2992. The source was found in its highest level of X-ray activity yet detected, a factor $\sim 23.5$ higher in 2--10 keV flux than the historical minimum. NGC 2992 is known to exhibit X-ray flaring activity on timescales of days to weeks, and the XMM data provide at least factor of $\sim 3$ better spectral resolution in the Fe K band than any previously measured flaring X-ray state. We find that there is a broad feature in the \sim 5-7 keV band which could be interpreted as a relativistic Fe K$\alpha$ emission line. Its flux appears to have increased in tandem with the 2--10 keV continuum when compared to a previous Suzaku observation when the continuum was a factor of $\sim 8$ lower than that during the XMM observation. The XMM data are consistent with the general picture that increased X-ray activity and corresponding changes in the Fe K$\alpha$ line emission occur in the innermost regions of the putative accretion disk. This behavior contrasts with the behavior of other AGN in which the Fe K$\alpha$ line does not respond to variability in the X-ray.