The Mass Distribution in the Elliptical Galaxy NGC 3377: Evidence for a 2 × 108 M☉ Black Hole
The Mass Distribution in the Elliptical Galaxy NGC 3377: Evidence for a 2 × 108 M☉ Black Hole
复制标题
椭圆星系 NGC 3377 中的质量分布：2 × 108 M☉ 黑洞存在的证据
DOI：
10.1086/300313
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
D. Richstone
中科院分区：
文献类型：
--
作者：
J. Kormendy;R. Bender;A. Evans;D. Richstone
本文研究了 E5 星系 NGC 3377 中心 35'' ≃ 1.7 kpc 的质量分布。利用加拿大-法国-夏威夷望远镜获得了恒星自转速度和速度色散剖面（见 σ* = 0.″20-0.″56）和 V 波段表面光度测量（σ* = 0.″20-0.″26）。 NGC 3377 在运动学上与 M32 相似：中心运动学梯度很陡。 r = 1 时，旋转速度存在未解决的中心上升，达到 V = 110 ± 3 km s−1（内部误差）。”0。表观速度色散从 1.″0⩽r<4'' 处的 95 ± 2 km s−1 上升到中心处的 178 ± 10 km s−1。为了寻找中心黑洞，我们在投影和视宁卷积后推导出符合上述观测结果和哈勃太空望远镜表面光度测量的三维速度和速度色散场。各向同性模型表明，在 r < 2'' 处，质光比上升 ∼4 倍，达到 M/LV ≳ 10。如果恒星的质光比 M/LV = 2.4 ± 0.2 随半径恒定，则 NGC 3377 包含一个中心大质量暗天体 (MDO)，可能是黑洞，质量为 M• ≃ (1.8 ± 0.8) × 108M⊙。一些论点表明 NGC 3377 可能几乎是各向同性的。然而，扁平各向异性最大熵模型可以在没有 MDO 的情况下拟合当前数据。因此，NGC 3377 中的 MDO 探测弱于我们的星系、M31、M32 和 NGC 3115 中的 MDO 探测。上述质量针对星系的 E5 形状以及线剖面高斯拟合给出的速度矩和速度之间的差异进行了校正。我们表明，后者的校正不会影响 MDO 检测的强度，但会稍微降低 M• 和 M/LV。在 3″ ≲ r ≲ 35″ 时，M/LV 恒定为 ∼2.4。因此，NGC 3377 的内部主要由正常的老年恒星群组成。在这个椭圆星系中，就像在核核主导的星系 NGC 3115 和 NGC 4594 中一样，晕暗物质在中心附近的半径范围内并不重要。
This paper is a study of the mass distribution in the central 35'' ≃ 1.7 kpc of the E5 galaxy NGC 3377. Stellar rotation velocity and velocity dispersion profiles (seeing σ* = 0.″20-0.″56) and V-band surface photometry (σ* = 0.″20-0.″26) have been obtained with the Canada-France-Hawaii Telescope. NGC 3377 is kinematically similar to M32: the central kinematic gradients are steep. There is an unresolved central rise in rotation velocity to V = 110 ± 3 km s−1 (internal error) at r = 1.″0. The apparent velocity dispersion rises from 95 ± 2 km s−1 at 1.″0⩽r<4'' to 178 ± 10 km s−1 at the center. To search for a central black hole, we derive three-dimensional velocity and velocity dispersion fields that fit the above observations and Hubble Space Telescope surface photometry after projection and seeing convolution. Isotropic models imply that the mass-to-light ratio rises by a factor of ∼4 at r < 2'', to M/LV ≳ 10. If the mass-to-light ratio of the stars, M/LV = 2.4 ± 0.2, is constant with radius, then NGC 3377 contains a central massive dark object (MDO), probably a black hole, of mass M• ≃ (1.8 ± 0.8) × 108 M⊙. Several arguments suggest that NGC 3377 is likely to be nearly isotropic. However, flattened anisotropic maximum entropy models can fit the present data without an MDO. Therefore, the MDO detection in NGC 3377 is weaker than those in our Galaxy, M31, M32, and NGC 3115. The above masses are corrected for the E5 shape of the galaxy and for the difference between velocity moments and velocities given by Gaussian fits to the line profiles. We show that the latter correction does not affect the strength of the MDO detection, but it slightly reduces M• and M/LV. At 3″ ≲ r ≲ 35″, M/LV is constant at ∼2.4. Therefore, the inner parts of NGC 3377 are dominated by a normal old stellar population. In this elliptical galaxy, as in the bulge-dominated galaxies NGC 3115 and NGC 4594, halo dark matter is unimportant over a significant range in radius near the center.