The supermassive black hole of Fornax A
The supermassive black hole of Fornax A
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DOI：
10.1111/j.1365-2966.2008.13960.x
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发表时间：
2008-09
影响因子：
4.8
通讯作者：
N. Nowak;R. Saglia;J. Thomas;R. Bender;R. Davies;K. G. M. Garching;Usm Munich;U. Austin
中科院分区：
文献类型：
--
作者：
N. Nowak;R. Saglia;J. Thomas;R. Bender;R. Davies;K. G. M. Garching;Usm Munich;U. Austin
射电星系天炉座A（NGC 1316）是天炉座星系团外围的一个突出的合并遗迹。它巨大的射电瓣表明存在一个强大的活动星系核（AGN），因此存在一个中心超大质量黑洞（SMBH）。FomaxA现在似乎处于活跃的黑洞增长和静止之间的过渡状态，正如原子核活动的强烈下降所示。研究处于这一演化阶段的天体对于理解黑洞膨胀和黑洞生长之间的联系尤为重要，这体现在黑洞质量和膨胀速度色散之间的M · -σ关系中。到目前为止，在Fomax A中测量SMBH质量是不可能的，因为它被灰尘笼罩，这使得光学测量是不可能的。我们提出了高分辨率的自适应光学辅助积分场数据的Fomax A，采取与SINFONI在甚大望远镜在K波段，灰尘的影响可以忽略不计。达到的空间分辨率为0.085角秒，大约是黑洞预期影响范围直径的五分之一。利用2.3 μm波段CO带头附近的区域测量了恒星的运动学。天炉座A在内部的0.33角秒内不旋转。速度分散度向中心增加。活动星系核的弱辐射对恒星运动学的影响仅限于0.06角秒以内。超过这个半径，恒星运动学在中心区域显得松弛。我们使用轴对称轨道模型来确定天炉座A中心SMBH的质量。我们的数据的三维性质提供了可能性，直接测试的数据与轴对称的一致性，分别模拟的四个象限。根据我们的动力学模型，得到了所有象限一致的SMBH质量M ·和动力学K s带质光比T，（M ·）= 1.3 × 10 8 M <$[rms（M.）= 0.4 x 10 8 M Ω]和（T）= 0.68 [rms（T）= 0.03]，证实了轴对称的假设。对于折叠和平均数据，我们发现M。= 1.5 + 0.75 - 0.8 × 10 8 M Ω，T = 0.65 + 0.075 - 0.05（3σ误差）。因此，Fomax A的黑洞质量与特里梅因等人的M · -σ关系在误差范围内是一致的，但比它的膨胀质量和马可尼和亨特关系的预期小了2.44倍。
The radio galaxy Fornax A (NGC 1316) is a prominent merger remnant in the outskirts of the Fornax cluster. Its giant radio lobes suggest the presence of a powerful active galactic nuclei (AGN) and thus a central supermassive black hole (SMBH). FomaxA now seems to be in a transition state between active black hole growth and quiescence, as indicated by the strongly declined activity of the nucleus. Studying objects in this evolutionary phase is particularly important in order to understand the link between bulge formation and black hole growth, which is manifested in the M • -σ relation between black hole mass and bulge velocity dispersion. So far, a measurement of the SMBH mass has not been possible in Fomax A, as it is enshrouded in dust which makes optical measurements impossible. We present high-resolution adaptive optics assisted integral-field data of Fomax A, taken with SINFONI at the Very Large Telescope in the K band, where the influence of dust is negligible. The achieved spatial resolution is 0.085 arcsec, which is about a fifth of the diameter of the expected sphere of influence of the black hole. The stellar kinematics was measured using the region around the CO bandheads at 2.3 μm. Fornax A does not rotate inside the inner ∼3 arcsec. The velocity dispersion increases towards the centre. The weak AGN emission affects the stellar kinematics in the inner ∼0.06 arcsec only. Beyond this radius, the stellar kinematics appears relaxed in the central regions. We use axisymmetric orbit models to determine the mass of the SMBH in the centre of Fornax A. The three-dimensional nature of our data provides the possibility to directly test the consistency of the data with axisymmetry by modelling each of the four quadrants separately. According to our dynamical models, consistent SMBH masses M • and dynamical K s -band mass-to-light ratios T are obtained for all quadrants, with (M • ) = 1.3 x 10 8 M ⊙ [rms(M.) = 0.4 x 10 8 M ⊙ ] and (T) = 0.68 [rms(T) = 0.03], confirming the assumption of axisymmetry. For the folded and averaged data, we find M. = 1.5 +0.75 -0.8 x 10 8 M ⊙ and T = 0.65 +0.075 -0.05 (3σ errors). Thus, the black hole mass of Fomax A is consistent within the error with the Tremaine et al. M • -σ relation, but is a factor of ∼4 smaller than expected from its bulge mass and the Marconi & Hunt relation.