We present a NuSTAR and XMM-Newton monitoring campaign in 2014/2015 of the Comptonthick Seyfert 2 galaxy, NGC 1068. During the 2014 August observation, we detect with NuSTAR a flux excess above 20 keV (32 ± 6 per cent) with respect to the 2012 December observation and to a later observation performed in 2015 February. We do not detect any spectral variation below 10 keV in the XMM-Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring material along the line of sight (from NH ≃ 1025 cm-2 to NH = 6.7 ± 1.0 × 1024 cm-2), which allows us for the first time to unveil the direct nuclear radiation of the buried active galactic nucleus in NGC 1068 and to infer an intrinsic 2-10 keV luminosity LX = 7+7-4 × 1043 erg s-1.
Marinucci, A., Bianchi, S., Matt, G., Alexander, D.M., Baloković, M., Bauer, F.E., et al. (2016). NuSTAR catches the unveiling nucleus of NGC 1068. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. LETTERS, 456(1), L94-L98 [10.1093/mnrasl/slv178].
NuSTAR catches the unveiling nucleus of NGC 1068
MARINUCCI, ANDREA;BIANCHI, STEFANO;MATT, Giorgio;
2016-01-01
Abstract
We present a NuSTAR and XMM-Newton monitoring campaign in 2014/2015 of the Comptonthick Seyfert 2 galaxy, NGC 1068. During the 2014 August observation, we detect with NuSTAR a flux excess above 20 keV (32 ± 6 per cent) with respect to the 2012 December observation and to a later observation performed in 2015 February. We do not detect any spectral variation below 10 keV in the XMM-Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring material along the line of sight (from NH ≃ 1025 cm-2 to NH = 6.7 ± 1.0 × 1024 cm-2), which allows us for the first time to unveil the direct nuclear radiation of the buried active galactic nucleus in NGC 1068 and to infer an intrinsic 2-10 keV luminosity LX = 7+7-4 × 1043 erg s-1.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
