Measurement of coronal properties of Seyfert galaxies from NuSTAR’s hard X-ray spectrum

Abstract

Precise measurement of the coronal properties of Active Galactic Nuclei (AGN) requires the availability of high signal-to-noise ratio data covering a wide range of X-ray energies. The Nuclear Spectroscopic Telescope Array (NuSTAR) which is highly sensitive to earlier missions in its operational energy range of 3–79 keV, allows us to arrive at precise estimates of the coronal parameters such as cut-off energy ($E_\mathrm{cut}$), coronal temperature ($\textit{kT}_e$) and geometry of the corona at least for sources that have $E_\mathrm{cut}$ within the energy range of NuSTAR. In this paper, we present our preliminary results on the spectral analysis of two Seyfert galaxies namely 3C 120 and NGC 4151 using NuSTAR observations in the 3–79 keV band. We investigated the continuum and coronal parameters, the photon index $\Gamma$, $E_\mathrm{cut}$ and $\textit{kT}_{e}$. By fitting the X-ray spectrum of 3C 120 and NGC 4151 with a simple phenomenological model, we found that both the sources showed a clear cut-off in their spectrum.