Evidence of heavy obscuration in the low-luminosity AGN NGC 4941

Abstract

We present the results obtained from timing and spectral studies of the highly obscured low luminosity active galactic nucleus NGC 4941 using data obtained from the nuclear spectroscopic telescope array and the Neil Gehrels Swift observatories. We find similar variability in 3–10 keV and 10–60 keV energy ranges with fractional rms variability of $\sim$14%. We investigate broad-band spectral properties of the source in 3–150 keV range, using data from NuSTAR and Swift/BAT, with phenomenological slab model and physically motivated mytorus model. From the spectral analysis, we find heavy obscuration with global average column density of the obscured material as $3.09^{+1.68}_{-1.01} \times 10^{24}$ $\hbox {cm}^{-2}$. Evidence of a strong reflection component is observed in the spectrum. We detect a strong iron line with equivalent width of $\sim$1 keV. From the slab model, we obtain the exponential cutoff energy as $177^{+92}_{-16}$ keV. From this, we estimate the Compton cloud properties with the hot electron temperature $kT_{\mathrm{e}} = 59^{+31}_{-5}$ keV and the optical depth $\tau = 2.7^{+0.2}_{-1.6}$.