Abstract:
Gravitational lensing is one of the powerful methods for astrophysical investigations where
General Relativity (GR) is being applied. But, the appropriate parameters incorporated
in GR are still at debate among the scientific communities. Especially, the incorporation
of cosmological constant Λ was controversial from its origin to its significance. However,
recent progress indicates that cosmological models require a form of dark matter-energy
sector that will behave in an old enough universe with energy content in the form of Λ. So,
here we worked out the effect of Λ in gravitational lensing where an effective refractive index
in vacuum is considered to accommodate it. Thus GR equations were being used to derive
lensing equation in the presence of Λ with simplifying boundary conditions. The adopted
method is so simple but agrees with the one derived from complex and more boundary value
considerations. Moreover, its significant at cosmological scale goes up to 2%, that cannot
be neglected.
