Publication Date:
2014-03-21
Description:
We present simultaneous XMM–Newton and NuSTAR observations of the ‘bare’ Seyfert 1 galaxy, Ark 120, a system in which ionized absorption is absent. The NuSTAR hard-X-ray spectral coverage allows us to constrain different models for the excess soft-X-ray emission. Among phenomenological models, a cutoff power law best explains the soft-X-ray emission. This model likely corresponds to Comptonization of the accretion disc seed UV photons by a population of warm electrons: using Comptonization models, a temperature of ~0.3 keV and an optical depth of ~13 are found. If the UV-to-X-ray optxagnf model is applied, the UV fluxes from the XMM–Newton Optical Monitor suggest an intermediate black hole spin. Contrary to several other sources observed by NuSTAR , no high-energy cutoff is detected with a lower limit of 190 keV.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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