Intrinsic errors of the central galactic mass derived from rotation curves under the influence of a weak non-axisymmetric potential.
Intrinsic errors of the central galactic mass derived from rotation curves under the influence of a weak non-axisymmetric potential.
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在弱非轴对称势的影响下，由旋转曲线得出的银河系中心质量的固有误差。
DOI：
10.1051/0004-6361:20021461
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发表时间：
2002
影响因子：
6.5
通讯作者：
Japan
中科院分区：
文献类型：
--
作者：
Jin Koda Keiichi Wada IoA;U. Tokyo;Nao;Japan
旋转曲线通常用于估计螺旋星系的质量分布，假设星际介质的圆周速度与星系离心力平衡。然而，由非轴对称引力势（例如恒星棒）引起的非圆周运动可能会扰乱速度场，导致质量估计错误，特别是在星系中心区域。这是因为视线速度取决于非轴对称流中的视角。从不同视角观察瞬态数值模拟中边缘星系的旋转曲线，我们从旋转曲线中获得了估计星系质量的误差。在最极端的情况下，即使棒势很弱，气体轨道的椭圆率在中心区域也高达 e 0:8。当旋转曲线被定义为位置-速度图的最高速度包络线时，对于15%的视角，从旋转曲线估计的质量比真实质量大五倍，并且对于任何视角，表观质量与真实质量之间的比率小于六。质量高估比低估更常见。
Rotation curves are often used to estimate the mass distribution of spiral galaxies, assuming that the circular ve- locities of the interstellar medium balance with the galactic centrifugal force. However, non-circular motions caused by a non-axisymmetric gravitational potential, such as a stellar bar, may disturb the velocity field, resulting in errors in mass estima- tion, especially in the central regions of galaxies. This is because the line-of-sight velocity depends on the viewing angles in a non-axisymmetric flow. Observing rotation curves of edge-on galaxies in time-dependent numerical simulations from dierent viewing angles, we obtain errors in the estimation of galactic mass from the rotation curves. In the most extreme case, the ellipticity of gas orbits is as high as e 0:8 in the central regions, even if the bar potential is weak. When rotation curves are defined as the highest velocity envelope of position-velocity diagrams, the mass estimated from the rotation curves is larger than the true mass by a factor of five for 15% of the viewing angles, and the ratio between the apparent mass and true mass is less than six for any viewing angle. The overestimation in mass occurs more frequently than the underestimation.