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astrostudent21
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- In gravitational lensing, the image magnification is defined as the image size over the source size. But many texts also give it as the determinant of the jacobian of the of the lens equation. How are these equivalent?
In gravitational lensing, the image magnification is defined as the image area over the source area. But many texts also give it as the inverse of the determinant of the jacobian, A, of the of the lens equation. My question is how these are equivalent.
The lens equation is β=θ-α(Dlens-source)/(Dlens)
The jacobian that describes it is then
many texts say that we can calculate the magnification as μ=1/det[A], but I have not found one that actually derives this relation from the initial definition of the magnification as the ratio of the image and source areas. I would really appreciate help from anyone who has experience with this topic!
The lens equation is β=θ-α(Dlens-source)/(Dlens)
The jacobian that describes it is then
many texts say that we can calculate the magnification as μ=1/det[A], but I have not found one that actually derives this relation from the initial definition of the magnification as the ratio of the image and source areas. I would really appreciate help from anyone who has experience with this topic!