Astronomy Stack Exchange
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Questions tagged [gravitational-lensing]

Questions regarding the bending of light by mass or energy.

General relativity predicts that matter and energy bend spacetime. As light travels through spacetime, it is influenced by other objects and follows a "bent" path. This phenomenon is known as gravitational lensing. It was first observed during the 1919 solar eclipse, by Sir Arthur Eddington, and was accepted as evidence of general relativity.

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With gravitational lensing, is it possible to mathematically compute the correct image of the galaxy that is being distorted?

There's been another report of gravitational lensing in the news. Wikipedia has a good image of an example of gravitational lensing taken by the Hubble Space Telescope. This brings me to wonder that, since they understand the math behind the…
Kevin Holmes
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What are the best candidates for solar lensing of exoplanets, and what would the results be?

If we were able to send a probe to 550AU from the Sun, which exoplanets could be examined, to what resolution, and what form would the examination take? It is radio telescopy only, or would it be possible to optically see what the surface of an…
tomh
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Is cosmic shear generally agreed to have been observed?

A review by Martin Kilbinger, 2015 says: Cosmic shear is the distortion of images of distant galaxies due to weak gravitational lensing by the large-scale structure in the Universe. Such images are coherently deformed by the tidal field of matter…
uhoh
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Does gravitational lensing provide time evolution information?

When we see multiple images of the same object because of the phenomenon of gravitational lensing, do all the images show the lensed object at the same point in time? Does it take the same amount of time for light from the lensed object to reach us…
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Images of gravitational lensing

I will expect that gravitational lensing should turn an object into a ring image. But I saw in some situations that instead multiple images are formed. For example, the Einstein-cross in the image below, consisting of four images: Why is it so?
velut luna
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Can time variations in gravitational lens paths be observed & is this useful?

When strong gravitational lensing causes multiple images such as an "Einstein Cross", I understand there is difference in the time it takes the light to reach us along each path. I was curious how accurately such time difference can be measured. I…
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Gravitational lensing

I was reading about gravitational lensing. I was just curious to know if there are any formulae or methods to find the angle at which the light deflects due to strong gravitational lensing? And how far should that massive object be present so that…
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Is Diffraction of light observed in gravitational lensing/microlensing?

As far as I understand the wave-optics effects,such e.g.diffraction at a caustic, are hardly observable in the gravitational lensing. Are there any observations where the diffraction paterns of the visible light have been seen? If not visible, which…
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What does the 'amplification factor' of gravitational microlensing mean?

At first I assumed the amplification factor meant an increase in brightness. But since the equation: $$A(u)=\frac{u^2+2}{u\sqrt{u^2+4}}$$ is independent of mass, this make no sense to me. Wouldn't everything be infinity magnified (if its mass…
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Hoag's object as an Einstein ring

What are the main arguments against Hoag's object in particular and Hoag-like objects in general to be explained as Einstein rings formed by a farther edge-on galaxy?
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Given that gravity bends the path of light, how confident can we be that galaxies are where they seem to be?

The widely known phenomenon termed gravitational lensing is believed to curve space, thereby affecting the path followed by light and other electromagnetic waves. This effect is associated principally with galaxies and galaxy clusters, as it…
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Cosmic shear: what is ellipticity for?

I understand that ellipticity is a very important concept in weak gravitational lensing because it describes the shape properties of the transformed galaxy. Shear, on the other hand, also describes the shape properties of the transformed galaxy.…
Gene
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Is gravitational lensing, optical in nature or topological?

If a large mass can adjust space geometry Like a blackhole or another star system Then is this effect optical in nature or topological? I know those sounds close, but a mirror reflects light. A mirror does not act as a portal (if you know the game…
Peter
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