Triggered high-state simultaneous XMM-Newton/NuSTAR observations of AM Herculis
Abstract
We report on simultaneous XMM-Newton/NuSTAR observations of the prototypical polar AM Herculis. The observations were triggered by an optical monitoring programme indicating a stable high accretion state. For the first time, AM Herculis could be observed in its reversed mode of accretion with imaging CCDs and full phase coverage for several subsequent binary cycles. The observations revealed several novelties: (1) Ultraviolet, soft and hard X-ray light curves displayed a complete new morphology; (2) a spectral analysis of the soft flares originating from the secondary (far) pole was possible for the first time; (3) extended phases of complete soft X-ray absorption were indicating a complex distribution of cold intra-binary matter; (4) the joint NuSTAR/XMM-Newton spectrum revealed the Compton reflection hump due to scattered radiation from the white-dwarf surface; (5) the Fe-line complex thought to originate from the main (regular) pole showed pronounced dissimilarities with its behavior in the regular accretion mode in year 2005.
- Publication:
-
The X-ray Universe 2017
- Pub Date:
- October 2017
- Bibcode:
- 2017xru..conf..208S