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This effect would make the mass act as a kind of gravitational lens. However, as he only considered the effect of deflection around a single star, he seemed to conclude that the phenomenon was unlikely to be observed for the foreseeable future since the necessary alignments between stars and observer would be highly improbable.
While gravitational lensing preserves surface brightness, as dictated by Liouville's theorem, lensing does change the apparent solid angle of a source. The amount of magnification is given by the ratio of the image area to the source area. For a circularly symmetric lens, the magnification factor μ is given by
Gravitational lensing is an effect of Albert Einstein's general relativity, which says that all matter bends light that passes by it. Strong gravitational lensing drastically alters the shape of an object on the sky; weak gravitational lensing slightly alters the shape of the object; and gravitational microlensing alters only the brightness of ...
In strong and weak lensing, the mass of the lens is large enough (mass of a galaxy or galaxy cluster) that the displacement of light by the lens can be resolved with a high resolution telescope such as the Hubble Space Telescope. With microlensing, the lens mass is too low (mass of a planet or a star) for the displacement of light to be ...
The Microlensing Observations in Astrophysics (MOA) telescope dome at the top of Mount John. Microlensing Observations in Astrophysics (MOA) is a collaborative project between researchers in New Zealand [1] and Japan, [2] led by Professor Yasushi Muraki of Nagoya University. [3]
The effects of foreground galaxy cluster mass on background galaxy shapes. The upper left panel shows (projected onto the plane of the sky) the shapes of cluster members (in yellow) and background galaxies (in white), ignoring the effects of weak lensing. The lower right panel shows this same scenario, but includes the effects of lensing.
The key difference between an embedded lens and a traditional lens is that the mass of a standard lens contributes to the mean of the cosmological density, whereas that of an embedded lens does not. Consequently, the gravitational potential of an embedded lens has a finite range, i.e., there is no lensing effect outside of the void.
Petters is known for his work in the mathematical theory of gravitational lensing.. Over the ten-year period from 1991 to 2001, Petters systematically developed a mathematical theory of weak-deflection gravitational lensing, beginning with his 1991 MIT Ph.D. thesis on "Singularities in Gravitational Microlensing". [12]