A NuSTAR census of coronal parameters in Seyfert galaxies

TL;DR

This study analyzes NuSTAR observations of nineteen bright Seyfert galaxies to investigate correlations between coronal parameters and other system properties, revealing an anti-correlation between optical depth and temperature but no link with black hole mass or accretion rate.

Contribution

It provides the first comprehensive analysis of coronal parameters in a sample of Seyfert galaxies using NuSTAR data, identifying specific parameter correlations.

Findings

Anti-correlation between coronal optical depth and temperature with >98% significance.

No correlation between coronal parameters and black hole mass or Eddington ratio.

Analysis of a well-defined sample of Seyfert galaxies with multi-instrument data.

Abstract

We discuss the results on the hot corona parameters of Active Galactic Nuclei that have been recently measured with NuSTAR. The values taken from the literature of a sample of nineteen bright Seyfert galaxies are analysed. Aims. The aim of this work is to look for correlations between coronal parameters, such as the photon index and cutoff energy (when a phenomenological model is adopted) or the optical depth and temperature (when a Comptonization model is used), with other parameters of the systems like the black hole mass or the Eddington ratio. We analysed the coronal parameters of the nineteen unobscured, bright Seyfert galaxies that are present in the Swift-BAT 70 months catalogue and that have been observed by NuSTAR, alone or simultaneously with others X-rays observatories such as Swift, Suzaku or XMM-Newton. We found an anti-correlation with a significance level > 98% between the coronal optical depth and the coronal temperature of our sample. On the other hand, no correlation between the above parameters and the black hole mass, the accretion rate and the intrinsic spectral slope of the sources is found.