Analytic expressions for mean magnification by a quadrupole gravitational lens

被引：22

作者：

Finch, TK

Carlivati, LP

Winn, JN

Schechter, PL

机构：

[1] MIT, Cambridge, MA 02139 USA

[2] Howard Univ, Washington, DC 20059 USA

[3] Harvard Univ, Cambridge, MA 02138 USA

[4] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

来源：

ASTROPHYSICAL JOURNAL | 2002年 / 577卷 / 01期

关键词：

gravitational lensing; methods : analytical;

D O I：

10.1086/342163

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We derive an analytic expression for the mean magnification due to strong gravitational lensing, using a simple lens model: a singular isothermal sphere embedded in an external shear field. We compute separate expressions for two-image and four-image lensing. For four-image lensing, the mean magnification takes a particularly simple form: (mu(4)) = 3.6/[gamma(1-gamma(2))], where gamma is the external shear. We compare our analytic results with a numerical evaluation of the full magnification distribution. The results can be used to understand the magnification bias that favors the discovery of four-image systems over two-image systems in flux-limited lens surveys.

引用

页码：51 / 56

页数：6

共 25 条

[1] FERMAT PRINCIPLE, CAUSTICS, AND THE CLASSIFICATION OF GRAVITATIONAL LENS IMAGES [J].