Volume 640, August 2020
|Number of page(s)||13|
|Published online||06 August 2020|
NuSTAR view of Swift/BAT AGN: The R−Γ correlation⋆
Astronomy Department, University of Geneva, Chemin d’Ecogia 16, 1290 Versoix, Switzerland
Accepted: 5 May 2020
Context. The reflection hump is a prominent feature in the hard X-ray spectrum of active galactic nuclei (AGN). Its exact shape and its correlation to other quantities provide valuable information about the inner and outer regions of an AGN.
Aims. Our main goal is to study the reflection hump in a large sample of nearby AGN. We aim to investigate the evolution of reflection with absorption and its correlation with the spectral index.
Methods. We analysed archived NuSTAR observations of the 70-month BAT catalogue AGN. By performing a detailed spectral analysis, we were able to constrain the spectral parameters and to investigate the reflection emission in a large sample of individual sources.
Results. The reflection strength was found to be strongly correlated with the power-law slope in unabsorbed sources, pointing towards disc reflection for these sources. Different possible explanations were tested and the most likely one is that the corona is moving either towards or away from the disc with a moderately relativistic velocity. An R − Γ correlation was not detected for absorbed sources. In addition, these AGN feature harder spectra, suggesting intrinsic differences between the two classes or a slab geometry for the X-ray source.
Key words: galaxies: active / galaxies: nuclei / galaxies: Seyfert / X-rays: galaxies
Tables 2–4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/640/A31
© ESO 2020
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