Questions tagged [gravitational-lensing]

Questions regarding the bending of light by mass or energy.

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48
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2answers
2k views

Two species of dark matter?

At this point in time, evidence for the existence of dark matter has accumulated in many ways: it affects galactic rotation curves plays a major role in cosmology, and the evolution of structure in ...
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If dark matter bends light, how do we know the stuff in the sky is where we think it is?

We measure movement, position, and many other things of an object in space because of its light and what we can measure with it. But as far as I know there's supposed to be a HUGE amount of dark ...
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Is it possible to detect gravitational lensing behind the Moon?

Eddington waited for an eclipse to happen to be able to observe gravitational lensing of the stars behind the Sun. And nowadays, amateurs can do the same thing. Of course, the Moon is much lighter ...
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Was the Sun's gravitational lensing observed in other solar eclipses than the one in 1919?

In 1919 the gravitational lensing by the Sun has been observed during a total solar eclipse. Did someone observe the lensing in any other total eclipses? Last year there was a total eclipse in Chile ...
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Using the Sun as a Gravitational Lens

Can the Sun be used as a gravitational lens to achieve better telescopic viewing? Can this effect be practically used to view celestial objects?
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1answer
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Are astronomers waiting to see something in an image from a gravitational lens that they've already seen in an adjacent image?

@RobJeffries' answer to the question Does gravitational lensing provide time evolution information? points out that there can be a substantial different in arrival times of light from a given source ...
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1k views

How can gravitational lensing makes a quasar appear brighter?

How can gravitational lensing makes a quasar brighter than it would in the absence of a foreground galaxy?
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416 views

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,...
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1answer
109 views

Is it possible to see stars that are gravitationally lensed by the sun from the ground?

Roughly 100 years ago, Eddington confirmed Einstein’s general relativity theory by photographing stars behind the obscured Sun during a total eclipse. A coronograph is a device that mimics what ...
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Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection

I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection of the right ascension and declination the galaxies relate to the center of ...
9
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1answer
99 views

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 ...
8
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1answer
574 views

Is it possible to observe strong gravitational lensing with amateur telescopes?

Strong gravitational lens systems like the Cosmic Horseshoe have been imaged by scientific space telescopes, but have any amateur astronomers accomplished this? Or are amateur/small ground based ...
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1answer
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What is the gravitational lensing focal distance of a white dwarf star?

I tried looking this up, but I couldn't find any formula on gravitational lensing distance. I know that our Sun's is about 550 AU, though further distances work too, as it's not a single focus due ...
8
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1answer
261 views

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 ...
8
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1answer
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What is the scale of things you can see with gravitational lensing?

I'm trying to understand the examples of gravity lensing (using the general relativity property of large masses to bend light like a lens). Most of the examples I see are of some galaxy (presumably ...
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How does gravity interact with a photon?

If photon is mass-less and gravity can interact only with matter, then how does gravity alter the trajectory of light?
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345 views

Is gravitational lensing a good way to search for negative mass?

Is it possible to verify negative mass with gravitational lensing? The following video proposes an idea that galaxies are surrounded by negative mass: https://youtu.be/MZtS7cBMIc4 Could this be ...
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Are our 'observations' of or near a black hole affected by gravity induced time dilation?

This answer made me wonder if matter/energy/events near a black hole are viewed (by us) in a very different time frame, how might that affect our measurements? ...
7
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1answer
427 views

Does gravitational lensing cause a black-hole to be the main 'source' of light in a given area?

Light gets bent around high-gravity sources, such as a black-hole. A source of light, say A, is directly observed in its 'true' position and some of its light is bent around the black-hole, X, which ...
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131 views

Telescope in Sun's gravity lens focus - pointing, gain, distortions

A telescope located in the gravitational focus of the Sun can use the Sun as a magnifying lens. The focus begins 550 AU away, but maybe a 700 or 1000 AU distance is needed to get rid of disturbances ...
7
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1answer
161 views

Going from the second moments of an object to its ellipticities and half-light-radius

I am studying ellipticity distributions of galaxies and am having trouble moving from the second central moment matrix (covariance matrix) to properties for an object such as its half-light radius. I ...
6
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1answer
187 views

Would gravitational waves be subject to external gravitational perturbations?

Given that the gravitational wave detected by LIGO was a very weak echo of a very distant event, could it have been "deviated" and distorted on its way here by a sufficiently massive black hole in ...
6
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1answer
108 views

Gravitational lensing of quasars

Are there any cases in which the gravitational lensing of a quasar has been observed in both visible light and in radio waves, and if so, is the radio-wave resolution good enough to show that the ...
6
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1answer
123 views

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 ...
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Would a black hole passing next to a star create a deadly focal point due to gravitational lensing?

Black holes bend all kinds of radiation thanks to their giant gravity. Now imagine that a black hole passes close to some star (we know of cases when black hole devours a star). Star emits massive ...
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Gravitational lensing in Newtonian physics

Famously, when Eddington attempted to measure gravitational lensing during the Eclipse, it was the measured magnitude of the lensing that gave gravity [pun, obviously, intended] to General Relativity -...
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What is the actual visual characteristics of a black hole?

Is there a safe distance in which a black hole can be observed with the human eye? What is a safe distance? I have seen many computer simulated and artist renditions, and I am not sure if they ...
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1answer
96 views

How massive does a planet need to be to create gravitational lensing?

Is it ever possible for starlight to be distorted in a noticeable way from something as small as a planet? I'm guessing that the chances of this working are better on a dense terrestrial planet than ...
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1answer
125 views

Can weak gravitational lensing or microlensing-induced wavefront distortion limit resolution of absurdly large aperture telescopes?

This is a theoretical question. This answer to the question If we had the right technology could we see a distant star in detail? (presumably space-based) primarily addresses the scaling of ...
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Can primordial black holes be found orbiting other stars?

A recent study suggests a that a primordial black hole may be orbiting the sun at and that they can be common near other star systems. What measurements and equipment can perhaps find BH's near ...
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3answers
746 views

How are gravitational lensing and dark matter related?

In a lecture which I attended at my institution on gravitational lensing, the lecturer linked gravitational lensing and dark matter research. Can anyone explain what is the relation of both?
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1answer
332 views

Algorithm to fit galaxies

Do you know of any other data analysis algorithm that fits 2-D analytic functions to galaxies and point sources directly to digital images, other than GALFIT? Especially to subtract lens light from ...
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1answer
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Need help understanding the recent observation of extra-galactic planets!

The new paper Probing Planets in Extragalactic Galaxies Using Quasar Microlensing (also in ArXiv) is too mind-boggling for me to understand exactly what is happening. I have some very basic ...
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1answer
116 views

Do we have to take gravitational lensing into consideration when measuring the size of exoplanets?

For the method of waiting for a planet to pass in front of a star. rather than just measuring the light that is blocked do we also have to take into consideration the light that may not be coming to ...
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1answer
325 views

Strong Gravitational Lensing Dataset

I'm a Machine Learning Student and I'm working on Strong Lensing Image Classification. this is a hot topic nowadays but strangely after days of searching and communicating with different people I ...
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1answer
121 views

How can a galaxy in-between our view and the galaxy behind it have a 'lensing effect'?

In this article, the author writes: This galaxy is so distant that it would have been invisible without the gravitational lensing effects of a large galaxy cluster called Abell 1689, located nearly ...
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What's the largest angle that light has been “seen to bend” by gravity? (of one object by a separate object)

Gravitational lensing is everywhere! because it falls off so slowly with $r$: $$\Delta \phi \approx \frac{4GM}{c^2r_0}.$$ That's the first order term. For a nice derivation see Viktor Toth's The ...
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What exactly would the resolution of an exoplanet hypothetically imaged by using the Sun as a gravitational lens be?

This video talks about how by sending a spacecraft to around 600 AU and beyond, we would could use the Sun as a gravitational lens and take clear detailed images of exoplanets light-years away. What ...
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4answers
115 views

Is it plausible to use other stars for the proposed FOCAL mission instead of the Sun?

For some time, the far-reaching and speculative idea of using the Sun as a gravitational lens has been floating around. See this and this. This would require sending a spacecraft about ~550 AU of a ...
3
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1answer
253 views

Why is this Einstein ring pink?

I'm having a hard time understanding this image in the CNN News item This glowing ring of light is from a distant galaxy. The caption (from this version of the article) says: This image shows ...
3
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1answer
308 views

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 ...
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1answer
137 views

How much solar energy concentrates at Jupiter's focal point via gravitational lensing?

How much solar energy concentrates at Jupiter's focal point via gravitational lensing?
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What exactly is it that is being magnified 50 times in this gravitational lensing observation?

In the Los Angeles Times news item Scientists get a rare view of a type Ia supernova magnified 50 times what exactly is magnified 50 times? This supernova is really very far away. Is it somehow ...
3
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1answer
108 views

How close are we to be able to detect and measure gravitational lensing inside the milky way?

Gravitational lensing takes advantage of statistically uniform distributions of background objects in order to infer a credible map of dark matter concentrations that isn't too noisy. If there are too ...
3
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1answer
134 views

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 ...
3
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1answer
107 views

How to differentiate between images of a gravitationally lensed object

The light coming from a distant galaxy or star can be distorted en route to Earth; this distortion is caused by the curvature of space when a massive object is present. My question is, how can we tell ...
3
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1answer
209 views

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 ...
2
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1answer
206 views

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 ...
2
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1answer
55 views

Has a gravitational microlensing event ever been predicted? If so, has it been observed?

This answer to Are astronomers waiting to see something in an image from a gravitational lens that they've already seen in an adjacent image? describes "Deja vu all over again" (SN "...
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1answer
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Cases of gravitational lensing resulting in a recognizable image of an extended object?

There are several different classifications of gravitational lensing phenomenon. Here I am asking for any examples of strong lensing where the lensed image of an extended object is magnified and ...