Axisymmetric, Three-Integral Models of Galaxies: A Massive Black Hole in NGC 3379
Axisymmetric, Three-Integral Models of Galaxies: A Massive Black Hole in NGC 3379
复制标题
星系的轴对称三积分模型：NGC 3379 中的大质量黑洞
DOI：
10.1086/301240
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
S. Tremaine
中科院分区：
文献类型：
--
作者：
K. Gebhardt;D. Richstone;J. Kormendy;T. Lauer;E. Ajhar;R. Bender;A. Dressler;S. Faber;C. Grillmair;J. Magorrian;S. Tremaine
利用哈勃空间望远镜FOS光谱和地面长缝光谱沿着4个位置角的视向速度分布，结合WFPC 2和地面图像对光线分布的约束，拟合了NGC 3379的轴对称三积分动力学模型.我们拟合的模型倾角从29°（内禀星系类型E5）到90°（内禀E1），黑洞质量从0到109 M Ω。最适合的黑洞质量范围为6 × 107至2 × 108 M Ω，取决于倾角。优选的倾角为90°（边缘上）;然而，由于我们假设M/LV恒定，对允许倾角的限制不是很强。最佳模型的速度椭球既不符合各向同性分布函数，也不符合二次积分分布函数。沿着长轴，速度椭球在最里面的仓处变为切向，在中间半径处变为径向，并且在最外面的仓处再次变为切向。由于黑洞的存在，旋转在小半径处迅速上升。对于可接受的模型，径向到切向[（σ + σ）/2]分散在中等半径范围内超过1.1 < σr/σt < 1.7，较小的黑洞需要较大的径向各向异性。与这些三积分模型相比，两积分各向同性模型高估了黑洞质量，因为它们不能提供足够的径向运动。然而，本文中提出的模型仍然包含限制性的假设，即，假设恒定的M/LV和球对称性，需要更多的模型来研究黑洞的性质在完整的一般性。
We fit axisymmetric three-integral dynamical models to NGC 3379 using the line-of-sight velocity distribution obtained from Hubble Space Telescope FOS spectra of the galaxy center and ground-based long-slit spectroscopy along four position angles, with the light distribution constrained by WFPC2 and ground-based images. We have fitted models with inclinations from 29° (intrinsic galaxy type E5) to 90° (intrinsic E1) and black hole masses from 0 to 109 M⊙. The best-fit black hole masses range from 6 × 107 to 2 × 108 M⊙, depending on inclination. The preferred inclination is 90° (edge-on); however, the constraints on allowed inclination are not very strong, owing to our assumption of constant M/LV. The velocity ellipsoid of the best model is not consistent with either isotropy or a two-integral distribution function. Along the major axis, the velocity ellipsoid becomes tangential at the innermost bin, radial in the midrange radii, and tangential again at the outermost bins. The rotation rises quickly at small radii owing to the presence of the black hole. For the acceptable models, the radial-to-tangential [(σ + σ)/2] dispersion in the midrange radii ranges over 1.1 < σr/σt < 1.7, with the smaller black holes requiring larger radial anisotropy. Compared with these three-integral models, two-integral isotropic models overestimate the black hole mass since they cannot provide adequate radial motion. However, the models presented in this paper still contain restrictive assumptions—namely, assumptions of constant M/LV and spheroidal symmetry—requiring yet more models to study black hole properties in complete generality.