Deflection of light by massive objects

Abstract

The discovery of gravitational lensing made the deflection of light as an important tool for astronomy and cosmology. Since Einstein introduced general theory of relativity for the expanding universe, the cosmological constant (Λ) is still a part of studies upto now. And in this work our main objective is in order to study the deflection of light by massive objects. Specifically we derived the lens equation in the presence of cosmological constant. Then we evaluated the contribution of cosmological constant to image size or image magnification. And finally we estimated the effect of cosmological constant to angular distances and image positions. The Einstein Field equation (EFE) is implemented to derive the lens equation in the presence of Λ. And using this lens equation for point mass system, we calculated image sizes, angular distances and image positions for the selected Einstein ringed systems. We expressed the results for the selected Einstein ringed objects by tables. As we expressed at the end of this work, the calculated image size or image magnification is a negative value and this implies that the image formed by gravitational lensing is de-magnified. And also we have seen the effect of cosmological constant to image position. The contribution of Λ for the Einstein correction part is 2% and this matches with other previous works.