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Compton-thick AGNs in the NuSTAR Era. II. A Deep NuSTAR and XMM-Newton View of the Candidate Compton-thick AGN in NGC 1358

2019; IOP Publishing; Volume: 870; Issue: 2 Linguagem: Inglês

10.3847/1538-4357/aaf1a0

1538-4357

X. Zhao, Stefano Marchesi, M. Ajello, L. Marcotulli, G. Cusumano, V. La Parola, C. Vignali,

Gamma-ray bursts and supernovae

Abstract We present the combined NuSTAR and XMM - Newton 0.6–79 keV spectral analysis of a Seyfert 2 galaxy, NGC 1358, which we selected as a candidate Compton-thick (CT) active galactic nucleus (AGN) on the basis of previous Swift /BAT and Chandra studies. According to our analysis, NGC 1358 is confirmed to be a CT-AGN using physically motivated models, at >3 σ confidence level. Our best fit shows that the column density along the line of sight of the obscuring material surrounding the accreting supermassive black hole is N H = (1.96–2.80) × 10 24 cm −2 . The high-quality data from NuSTAR give the best constraints on the spectral shape above ∼10 keV to date on NGC 1358. Moreover, by combining NuSTAR and XMM - Newton data, we find that the obscuring torus has a low covering factor ( f c < 0.17), and the obscuring material is distributed in clumps, rather than uniformly. We also derive an estimate of NGC 1358's Eddington ratio, finding it to be λ Edd ∼ <?CDATA ${4.7}_{-0.3}^{+0.3}$?> × 10 −2 , which is in acceptable agreement with previous measurements. Finally, we find no evidence of short-term variability, over a ∼100 ks time span, in terms of both line-of-sight column density and flux.