Broad-band X-ray spectral analysis of the Seyfert 1 galaxy GRS 1734-292

Abstract

We discuss the broad-band X-ray spectrum of GRS 1734−292 obtained from non-simultaneous XMM-Newton and NuSTAR (Nuclear Spectroscopic Telescope Array) observations, performed in 2009 and 2014, respectively. GRS1734−292 is a Seyfert 1 galaxy, located near the Galactic plane at z = 0.0214. The NuSTAR spectrum (3–80 keV) is dominated by a primary power-law continuum with Γ = 1.65 ± 0.05 and a high-energy cut-off Ec = 53(+11)(−8) keV, one of the lowest measured by NuSTAR in a Seyfert galaxy. Comptonization models show a temperature of the coronal plasma of kTe = 11.9 (+1.2)(−0.9) keV and an optical depth, assuming a slab geometry, τ=2.98(+0.16)(−0.19) or a similar temperature and τ=6.7(+0.3)(−0.4) assuming a spherical geometry. The 2009 XMM–Newton spectrum is well described by a flatter intrinsic continuum (Γ=1.47(+0.07)(−0.03)) and one absorption line due to Fe XXV Kα produced by a warm absorber. Both data sets show a modest iron Kα emission line at 6.4 keV and the associated Compton reflection, due to reprocessing from neutral circumnuclear material.