Galaxy Structures and External Perturbations in Gravitational Lenses
Galaxy Structures and External Perturbations in Gravitational Lenses
复制标题
DOI：
10.1093/pasj/56.2.253
复制
发表时间：
2004-04
影响因子：
2.3
通讯作者：
Yozo Kawano;M. Oguri;T. Matsubara;S. Ikeuchi
中科院分区：
文献类型：
--
作者：
Yozo Kawano;M. Oguri;T. Matsubara;S. Ikeuchi
在对强引力透镜系统进行建模时，通常采用简单的模型，例如奇异等温椭圆密度加上最低阶外部扰动。然而，如果实际质量分布比假设模型中的质量分布更复杂，那么这种简单的模型可能会误导我们。特别是，质量模型的假设对于研究通量比异常至关重要，通量比异常已被建议作为冷暗物质子结构的证据。我们使用幂律傅立叶模型重新研究了四个四透镜系统，该模型具有物理意义清晰和线性方法适用的优点，以及简单的奇异等温椭圆密度模型。我们还研究了外部扰动的影响，包括奇异等温球、最低阶膨胀和下一阶膨胀。我们发现主星系和/或外部摄动的cos3θ项显着降低了PG 1115+080和B1422+231中的χ 2 。特别是，假设通量不确定性为 5%，我们可以通过下一阶外部扰动重现 B1422+231 的通量比，这表明外部扰动不能通过简单的奇异等温球近似来描述。另一方面，即使使用我们的模型，我们也无法很好地拟合 B0712+472 和 B2045+265，尽管 χ 2 与
In modeling strong gravitational lens systems, one often adopts simple models, such as singular isothermal elliptical density plus lowest-order external perturbation. However, such simple models may mislead us if the real mass distribution is more complicated than that in the assumed models. In particular, assumptions on mass models are crucial in studying flux ratio anomalies that have been suggested as evidence for a cold dark-matter substructure. We reinvestigated four quadruple lens systems using power-law Fourier models, which have advantages of clear physical meanings and the applicability of a linear method, as well as a simple singular isothermal elliptical density model. We also investigated the effect of external perturbations, including a singular isothermal sphere, lowest-order expansion, and next-order expansion. We have found that the cos3θ terms of the primary galaxy and/or of external perturbation significantly reduce the χ 2 in PG 1115+080 and B1422+231. In particular, we could reproduce the flux ratios of B1422+231 with next-order external perturbation assuming 5% flux uncertainties, suggesting that external perturbation cannot be described by a simple singular isothermal sphere approximation. On the other hand, we could not fit B0712+472 and B2045+265 very well even with our models, although the χ 2 were reduced compared with