Weak Lensing Observables
In weak gravitational lensing, the Jacobian is mapped out by observing the effect of the shear on the ellipticities of background galaxies. This effect is purely statistical; the shape of any galaxy will be dominated by its random, unlensed shape, but lensing will produce a spatially coherent distortion of these shapes.
Read more about this topic: Gravitational Lensing Formalism
Famous quotes containing the word weak:
“We have no participation in Being, because all human nature is ever midway between being born and dying, giving off only a vague image and shadow of itself, and a weak and uncertain opinion. And if you chance to fix your thoughts on trying to grasp its essence, it would be neither more nor less than if your tried to clutch water.”
—Michel de Montaigne (1533–1592)