High-energy monitoring of NGC 4593 with XMM-Newton and NuSTAR. X-ray spectral analysis
Bianchi, S.; Cappi, M.; Ponti, G.; Petrucci, P. -O.; De Marco, B.; Malzac, J.; Matt, G.; De Rosa, A.; Ursini, F.; Marinucci, A.; Tortosa, A.
France, Italy, Germany
Abstract
We present results from a joint XMM-Newton/NuSTAR monitoring of the Seyfert 1 NGC 4593, consisting of 5 × 20 ks simultaneous observations spaced by 2 d, performed in 2015 January. The source is variable, both in flux and spectral shape, on time-scales down to a few ks and with a clear softer-when-brighter behaviour. In agreement with past observations, we find the presence of a warm absorber well described by a two-phase ionized outflow. The source exhibits a cold, narrow and constant Fe Kα line at 6.4 keV, and a broad component is also detected. The broad-band (0.3-79 keV) spectrum is well described by a primary power law with Γ ≃ 1.6-1.8 and an exponential cut-off varying from 90^{+ 40}_{- 20} to >700 keV, two distinct reflection components, and a variable soft excess correlated with the primary power law. This campaign shows that probing the variability of Seyfert 1 galaxies on different time-scales is of prime importance to investigate the high-energy emission of active galactic nuclei.