On the Nature of the High-Energy Rollover in 1H 0419-577
Links to Fileshttps://arxiv.org/pdf/1802.00795.pdf
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Type of Work14 pages
Citation of Original PublicationMonthly Notices of the Royal Astronomical Society
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A NuSTAR/Swift observation of the luminous Seyfert 1 galaxy 1H 0419-577 taken during 2015 reveals one of the most extreme high energy cut-oﬀs observed to date from an AGN - an origin due to thermal Comptonization would imply a remarkably low coronal temperature kT ∼ 15 keV. The low energy peak of the spectrum in the hard X-ray NuSTAR band, which peaks before the expected onset of a Compton hump, rules out strong reﬂection as the origin of the hard excess in this AGN. We show the origin of the high energy rollover is likely due to a combination of both thermal Comptonization and a intrinsically steeper continuum, which is modiﬁed by absorption at lower energies. Furthermore, modeling the broadband XUV continuum shape as a colour-corrected accretion disc, requires the presence of a variable warm absorber to explain all ﬂux and spectral states of the source, consistent with the previous work on this AGN. While absorber variations produce marked spectral variability in this AGN, consideration of all ﬂux states allows us to isolate a colourless component of variability that may arise from changes in the inner accretion ﬂow, typically at around 10 rg.