NuSTAR Uncovers an Extremely Local Compton-thick AGN in NGC 4968
NuSTAR Uncovers an Extremely Local Compton-thick AGN in NGC 4968
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DOI：
10.3847/1538-4357/ab552c
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
S. LaMassa;T. Yaqoob;P. Boorman;P. Tzanavaris;N. Levenson;P. Gandhi;A. Ptak;T. Heckman
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文献类型：
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作者：
S. LaMassa;T. Yaqoob;P. Boorman;P. Tzanavaris;N. Levenson;P. Gandhi;A. Ptak;T. Heckman
本文对NGC 4968的Chandra和努斯塔光谱进行了分析。NGC 4968是一个直径为44 Mpc、直径为12 μm的Seyfert 2星系，被康普顿厚度的遮蔽气体层所包裹。我们没有发现钱德拉和努斯塔观测之间（相隔2年），也没有两个努斯塔观测之间（相隔10个月）的变化的证据。使用自洽的X射线模型，我们排除了遮蔽介质几乎是球形和均匀的情况，这与3 × 1023 cm−2）所暗示的结果相矛盾，根据X射线光谱模型，康普顿厚和康普顿薄的解决方案都是允许的。光谱模型提供了一系列活动星系核的内禀连续统参数和2-10 keV的亮度（L2-10 keV，intrinsic），其中L2-10 keV，intrinsic的高端与12 μm亮度（L2-10 keV，intrinisc = 7 × 1042 erg s−1）的预期一致。与之前努斯塔观测到的康普顿厚度的活动星系核相比，NGC 4968是最具X射线发光特性的活动星系核之一。然而，尽管它的距离很近，并且具有相对较高的内在X射线光度，但它在105个月的Swift-Burst Alert望远镜调查中没有被发现，这强调了多波长选择对于获得最完整的最隐藏黑洞普查的重要性。
We present the analysis of Chandra and NuSTAR spectra of NGC 4968, a local (D ∼ 44 Mpc) 12 μm selected Seyfert 2 galaxy, enshrouded within Compton-thick layers of obscuring gas. We find no evidence of variability between the Chandra and NuSTAR observations (separated by 2 yr), nor between the two NuSTAR observations (separated by 10 months). Using self-consistent X-ray models, we rule out the scenario where the obscuring medium is nearly spherical and uniform, contradicting the results implied by the 3 × 1023 cm−2), with both Compton-thick and Compton-thin solutions permitted, depending on the X-ray spectral model. The spectral models provide a range of intrinsic AGN continuum parameters and implied 2–10 keV luminosities (L2–10 keV,intrinsic), where the higher end of L2–10 keV,intrinsic is consistent with expectations from the 12 μm luminosity (L2–10 keV,intrinisc ∼ 7 × 1042 erg s−1). Compared with Compton-thick AGN previously observed by NuSTAR, NGC 4968 is among the most intrinsically X-ray luminous. However, despite its close proximity and relatively high intrinsic X-ray luminosity, it is undetected by the 105 month Swift-Burst Alert Telescope survey, underscoring the importance of multiwavelength selection for obtaining the most complete census of the most hidden black holes.