NuSTAR spectral analysis of two bright Seyfert 1 galaxies: MCG +8-11-11 and NGC 6814

Abstract

We report on the NuSTAR observations of two bright Seyfert 1 galaxies, namely MCG +8-11-11 (100 ks) and NGC 6814 (150 ks). The main goal of these observations was to investigate the Comptonization mechanisms acting in the innermost regions of AGN which are believed to be responsible for the UV/X-ray emission. The spectroscopic analysis of the NuSTAR spectra of these two sources revealed that although they had different properties overall (black hole masses, luminosity and Eddington ratios) they had very similar coronal properties. Both presented a power law spectrum with a high-energy cutoff at $\sim 150-200$ keV, a relativistically broadened Fe K$\alpha$ line and the associated disk reflection component, plus a narrow iron line likely emitted in Compton thin and distant matter. The intrinsic continuum was well described by Comptonization models that show for MCG +8-11-11 a temperature of the coronal plasma of kT${}_{\mathrm{e}}\sim$ 60 keV and an extrapolated optical depth $\tau$=1.8; for NGC 6814 the coronal temperature was kT${}_{\mathrm{e}}\sim$ 45 keV with an extrapolated optical depth of $\tau$=2.5. We compare and discuss these values to some most common Comptonization models which aim at explaining the energy production and stability of coronae in active galactic nuclei.

References in corpus (3)

• The role of the reflection fraction in constraining black hole spin
• Properties of AGN coronae in the NuSTAR era II: hybrid plasma
• The narrow Fe K$\alpha$ line and the molecular torus in active galactic nuclei - an IR/X-ray view

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• Eclipsing the X-ray emitting region in the active galaxy NGC 6814
• Coronal properties of black hole X-ray binaries in the hard state as seen by NuSTAR and Swift
• NuSTAR hard X-ray spectra of radio galaxies
• Study of X-ray variability and coronae of Seyfert galaxies using NuSTAR
• A broadband X-ray spectral study of the Seyfert 1 galaxy ESO 141--G055 with XMM-Newton and NuSTAR
• Investigating the interplay between the coronal properties and the hard X-ray variability of active galactic nuclei with NuSTAR
• The lively accretion disk in NGC 2992. II. The 2019/2021 X-ray monitoring campaigns
• Are Compton-thin AGNs Globally Compton Thin?
• Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum
• Intensive X-ray/UVOIR continuum reverberation mapping of the Seyfert AGN MCG+08-11-11