High-energy monitoring of Seyfert galaxies: the case of NGC 4593

TL;DR

This study presents initial findings from a coordinated XMM-Newton and NuSTAR monitoring of NGC 4593, revealing rapid variability in flux and spectral shape, with a soft excess linked to the primary emission.

Contribution

First simultaneous X-ray monitoring of NGC 4593 with XMM-Newton and NuSTAR showing flux and spectral variability on short timescales.

Findings

Source flux and spectral shape vary on ks timescales.

Spectrum softens as brightness increases.

Variable soft excess correlates with primary continuum.

Abstract

We discuss preliminary results from a joint XMM-Newton and NuSTAR monitoring program on the active galactic nucleus NGC 4593, consisting of 5x20 ks observations, spaced by two days, performed in January 2015. The source is found to be variable, both in flux and spectral shape, on time scales as short as a few ks. The spectrum clearly softens when the source brightens. A simple timing analysis suggests the presence of a variable soft excess that correlates with the primary continuum.