标题： HE 2149-2745透镜星系的检测 显示英文标题

标题： Detection of the lensing galaxy in HE 2149-2745

摘要： 我们获得了在1角秒观测条件下的引力透镜QSO对HE 2149-2745 A,B（QSO红移z=2.033；角距离theta_AB=1.71角秒）的新BVR波段图像。减去一个缩放的点扩散函数显示出一个角尺寸与theta_AB相当、R星等为20.4的延伸天体，位于QSO之间且与两者等距。该系统的几何结构使我们将其解释为产生双QSO图像的透镜物质。对星系表面亮度分布的拟合表明这是一个椭圆星系，这进一步由吸收谱中没有Mg II得到支持。透镜星系在B和V波段未被检测到。我们讨论了由观测约束的此几何结构的可能透镜模型以及对透镜质量和红移的影响。 显示英文摘要

摘要： We have obtained new BVR-band images of the gravitationally lensed QSO pair HE 2149-2745 A,B (QSO redshift z=2.033; angular separation theta_AB=1.71 arcsec), under 1 arcsec seeing conditions. Subtraction of a scaled point-spread-function reveals an extended object of angular size comparable to theta_AB, and R magnitude of 20.4 lying between and equidistant to the QSOs. The geometry of the system leads us to interpret this object as the lensing agent responsible for the double QSO images. A fit to the galaxy surface brightness profile indicates an elliptical galaxy, which is further supported by the absence of Mg II in absorption. The lensing galaxy is not detected in B and V. We discuss possible lens models for this geometry constrained by our observations and consequences for the mass and redshift of the lens.