High-energy monitoring of NGC 4593 with XMM-Newton and NuSTAR. X-ray spectral analysis

TL;DR

This study analyzes the X-ray spectral variability of Seyfert 1 galaxy NGC 4593 using joint XMM-Newton and NuSTAR observations, revealing flux and spectral shape changes, warm absorber features, and variable high-energy emission components.

Contribution

First simultaneous multi-epoch X-ray monitoring of NGC 4593 with detailed spectral analysis, highlighting variability patterns and spectral components in high-energy emission.

Findings

Detection of flux and spectral variability on ks timescales.

Presence of a two-phase warm absorber outflow.

Identification of a variable soft excess and high-energy cutoff.

Abstract

We present results from a joint Xmm-Newton/NuSTAR monitoring of the Seyfert 1 NGC 4593, consisting of 5x20 ks simultaneous observations spaced by two days, performed in January 2015. 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 K alpha 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 Gamma=1.6-1.8 and an exponential cut-off varying from 90(+40,-20) keV 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 AGNs.