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 $E_{\rm c}=53^{+11}{-8}$ keV, one of the lowest measured by NuSTAR in a Seyfert galaxy. Comptonization models show a temperature of the coronal plasma of $kT{\rm e}=11.9^{+1.2}{-0.9}$ keV and an optical depth, assuming a slab geometry, $\tau =2.98^{+0.16}{-0.19}$ or a similar temperature and $\tau =6.7^{+0.3}{-0.4}$ assuming a spherical geometry. The 2009 XMM–Newton spectrum is well described by a flatter intrinsic continuum ($\Gamma = 1.47^{+0.07}{-0.03}$) 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.