The lively accretion disk in NGC 2992. II. The 2019/2021 X-ray monitoring campaigns

TL;DR

This study presents a detailed analysis of the short and long-term X-ray variability of NGC 2992, revealing a highly variable nuclear continuum and a Compton-thin circumnuclear medium through extensive observations with Swift, XMM-Newton, and NuSTAR.

Contribution

It provides the first comprehensive analysis of NGC 2992's X-ray variability over two years, combining multiple observatories to characterize its spectral and flux changes.

Findings

NGC 2992 shows flux variability by a factor of 20 in 2-10 keV band.

The spectral index is consistently around 1.69, indicating a power-law continuum.

The circumnuclear medium is globally Compton-thin with N_H ~ 7.8 x 10^21 cm^-2.

Abstract

We report on the short and long term X-ray properties of the bright nearby Seyfert 2 galaxy NGC 2992, which was extensively observed with Swift, XMM-Newton and NuSTAR. Swift targeted the source more than 100 times between 2019 and 2021 in the context of two monitoring campaigns. Both time-averaged and time-resolved analyses are performed, and we find that the short-to-long term spectral properties of NGC 2992 are dominated by a highly variable nuclear continuum. The source varied in the 2-10 keV energy band from 0.6 to 12 $\times$ 10$^{-11}$ erg cm$^{-2}$ s$^{-1}$ during the two year long Swift monitoring. The fastest 2-10 keV flux change (by a factor of $\sim60\%$) occurred on a timescale of a few hours. The overall emission spectrum of the source is consistent with a power law-like continuum ($\Gamma=1.69\pm0.01$) absorbed by a constant line-of-sight column density N$_{H}=(7.8\pm0.1)\times$ 10$^{21}$ $\rm cm^{-2}$. The reflected emission is likely due to matter with an average column density N$_{\rm H}=(9.6\pm2.7)\times$ 10$^{22}$ $\rm cm^{-2}$, thus NGC 2992 appears to have a globally Compton-thin circumnuclear medium. This scenario is fully supported by an independent analysis of the fractional variability and by XMM-Newton multi-year spectra.