The NuSTAR View of Reflecting and Absorbing Circumnuclear Material in AGN
Abstract
The physical conditions and precise geometry of the accreting circumnuclear material in the vicinity of supermassive black holes remain open and critical questions. Between July 2012 and February 2013, NuSTAR and XMM-Newton performed four long-look joint observations of the type 1.8 Seyfert, NGC 1365. We have analyzed the variable absorption seen in these observations in order to characterize the geometry of the absorbing material. Two of the observations caught NGC 1365 in an unusually low absorption state, revealing complexity in the multi-layer absorbers which had previously been hidden, including a the Compton-thick torus, BLR clouds, and a patchy absorber with a variable column around 1022 cm-2 and a line of sight covering fraction of 0.3-0.9 which responds directly to the intrinsic source flux, possibly due to a wind geometry. We have also analyzed two NuSTAR observations of NGC 7582, a well-studied X-ray bright Seyfert 2 with moderately heavy highly variable absorption and strong reflection spectral features. Changes in the spectral shape and high reflection fractions have led to competing explanations: 1) the central X-ray source partially “shut off”, decreasing in intrinsic luminosity, with a delayed decrease in reflection features due to the light-crossing time of the Compton-thick material or 2) the source became more heavily obscured, with only a portion of the power law continuum leaking through. The high quality of the NuSTAR spectra above 10 keV give us the best look at the reflection hump to date and allow us to test these two scenarios.
- Publication:
-
AAS/High Energy Astrophysics Division #15
- Pub Date:
- April 2016
- Bibcode:
- 2016HEAD...1510623R