Questions tagged [gravitational-lensing]

Questions regarding the bending of light by mass or energy.

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Is gravitational lensing "additive" in a line of sight?

As usually depicted, gravitational lensing implies, at least, three objects: a distant source, an observer, and a "massive enough" object in the middle, where enough is the mass needed to ...
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For detection of distant galaxies by gravitational lensing-induced magnification, roughly what are the distance ratios from the lensing systems?

Discussion in comments under the question Does seeing a gravitationally lensed/magnified galaxy imply that they could also see us as well? have got me wondering about the geometry behind detection of ...
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Does seeing a gravitationally lensed/magnified galaxy imply that they could also see us as well?

Does an observer in that galaxy see our galaxy magnified as well?
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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 ...
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Would be possible to detect Planet Nine as a microlensing event along the line of its projected orbit?

Theoretically proposed by Konstantin Batygin and Mike Brown (@Caltech), Planet Nine could have a mass of $\sim 6.3 \pm 2 M_{\oplus}$. Even though I don't know if the hypothesis is still feasible at ...
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Can we measure how fast space is expanding from how quickly gravitationally lensed galaxies or stars are blurring or getting sharper?

A galaxy that lenses another celestial body should as it moves away from Earth alter the sharpness of what it lenses by gravity. Could this be used to determine how quickly space is expanding?
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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 ...
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If you were on a planet orbiting a star that has a black hole companion, could you see light from your host star bent 180 degrees?

I realize that there is a distance from a black hole where photons can orbit. I understand that this orbit is very unstable, but I am concerned with photons just outside this range. Could the black ...
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Is it possible to detect gravitational lensing of both light and gravitational waves originating from the same event?

Is it theoretically possible to detect gravitational lensing of both light and gravitational waves, when both originate from the same source/event (merger of two stellar black holes or merger of two ...
Alex's user avatar
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Does the other side of the Big Bang factor into JWST observations?

Our (roughly) 13.6 billion light year view to the point of origin (big bang) is just along a radial axis. Assuming most matter ejected in a (roughly) spherical pattern, the diameter of the universe is ...
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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 ...
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What is the galactocentric aberration?

At the Wikipedia about an aberration, there is the phrase: a recommended galactocentric aberration constant of 5.8 µas/yr What is the galactocentric aberration? How is it calculated correctly? An ...
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Viewing black holes?

How could you possibly see a black hole when there are stars etc in front of it and then the matter being drawn into it , all you would view surely would be the objects in front of the black hole ?
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Mega Telescope using gravitational lensing and interferometry

I have been thinking about this crazy telescope idea, but I am not smart enough to understand if it's technically possible. I understand from an engineering and practical point of view it's a long way ...
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Is it theoretically possible to see a spiral galaxy head on, and side on, if there is a convenient gravitational lensing effect?

I was thinking this when I heard Professor Mike Merrifield say something to the effect of "unfortunately we've never seen the same galaxy side on and head on, so we can compare notes on our ...
Rabbi Kaii's user avatar
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Does gravitational lensing disprove the cosmic expansion theory [closed]

Recently there was a picture from the JWST that showed a galaxy that was 12.5 billion light years away. Its light had been lensed by a galaxy that was 5 billion light years away. In a static universe ...
Michael Mcgarry's user avatar
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Is there any method that enables us to observe the 3D large-scale spatial distribution of the dark matter?

Can we get the three-dimensional spatial distribution of dark matter through gravitational lensing? If not, is there any other way?
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How much does foreground clumping affect the estimated sizes of high-redshift objects?

I've always converted angular to linear size by using the angular-diameter distance without really thinking about it. But in light of recent stories about high-$z$ galaxies observed by JWST being ...
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Can two Stars form an Einstein Ring?

We know that when two galaxies are perfectly aligned they form an Einstein Ring by gravitational lensing but can two stars form it? We know gravitational bending by stars, but can two perfectly ...
Sandeep Jassal's user avatar
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If I can't unscramble an egg, how do Astronomers unscramble views gravitationally lensed by complex mass distributions?

Quanta Magazine's Two Weeks In, the Webb Space Telescope Is Reshaping Astronomy highlights two submissions to arXiv soon after the first images were released: "Three days later, just minutes ...
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Gravitational mirroring: Can we theoretically see the Milky Way using a telescope?

As I am watching the beautiful deep field picture of the James Webb Space Telescope. I noticed the gravitational lensing. So I asked myself whether it is possible somehow a successive cluster of ...
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Could "gravitational atom” black hole be detected using observation of gravitational microlensing?

D. Baumann et al., published the article hypothesizing existence of "gravitational atom” black holes (not sure whether those are just stellar ones or also those could be supermassive black holes ...
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Black hole magnification factor

Given a black hole of mass $M$ which has a distance $D_1$ to Earth and $D_2$ to a galaxy being magnified, what is the magnification factor? And a follow-up question: Does it magnify across the ...
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Is there a better explanation of this picture showing the very distant star "Earendel"?

"Close-up of the tiny region where Earendel happened to fall right on top of the narrow line where the magnification increases by (tens of) thousands of times. A cluster of many stars is seen ...
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If the Sun was replaced with a sun-mass black hole, would it be visually detectable?

Assuming it had no accretion disk, could we still detect e.g. distortions of the background star field?
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What is the maximum radius of an Einstein ring?

Is there an upper limit to how far out an Einstein ring can be visible? For black holes, is it a fixed multiple of their Schwarzschild radius?
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In shear component $\gamma_1, \gamma_2$ of weak lensing, Why does the defining with $2\phi$ reflect "real angle"?

From the review paper Bartelmann and schneider, 1999) [Weak Gravitational Lensing], page 48. Like above, $\gamma_1 \equiv \left| \gamma \right| \cos(2\phi), \gamma_2 \equiv \left| \gamma \right|\sin(2\...
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Finding the Laplacian of the deflection potential: I obtain 4𝜅(𝜃⃗ ), not 2𝜅(𝜃⃗ ). Why am I wrong?

From the review paper Bartelmann and schneider, 1999) Weak Gravitational Lensing, page 48. Like above, the Laplacian of the deflection function is convergence, $\kappa(\vec{\theta})$. I tried to ...
BAO's user avatar
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Is a black hole found in the centre of the low-surface-brightness and dark-matter-free galaxy AGC 114905

Per information found on Internet: AGC 114905 was discovered while observing the constellation Pisces with the VLA ground-based radio telescope. The galaxy is about 250 million light-years distant ...
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How do we know that objects that appear in duplicate or triplicate, etc. due to strong gravitational lensing aren't actually multiple objects?

If we are looking at faraway objects, there is no parallax view, correct? So isn't there a chance that an object that appears multiple due to strong foreground gravitational lensing is actually ...
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How does one think about optical depth in the context of gravitational microlensing? Is it measured or deduced from observations? Used for planning?

This excellent answer to Which studies prior to 2018 "claimed to find evidence of extragalactic planets in the Andromeda galaxy"? Which instrument was used? introduces the technique of "...
uhoh's user avatar
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How was the recently publicized Hubble image of a distant galaxy showing clearly resolved lensed in an Einstein ring produced? When was it produced?

The 24-Sep-2021 NASA Goddard video Einstein Ring Spotted by Hubble and it's Goddard Media Studio's page Einstein Ring Spotted By Hubble discuss the image, but don't really give credit to how it was ...
uhoh's user avatar
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Is quasar 2M1310-1714 outside the observable universe?

This Einstein ring Image credit: NASA / ESA / Hubble / T. Treu / Judy Schmidt shows multiple images of the quasar 2M1310-1714. Its distance is quoted at 17 billion light years and although the age ...
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Could we see small objects like animals on an exoplanet using Solar Gravitational Lensing (SGL) if we could use any star or a black hole for lensing?

Theoretically, if a telescope is positioned in a focal point of a supermassive black hole or a star much more massive than the Sun, would there be a limit to how far away an observable planet can be ...
odddirector's user avatar
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Can single black holes be observed by its lensing effect?

A comment on a question I asked left me confused. I asked about the possibility of observing a binary black hole by examining the lensing the binary produces. A binary has a different lensing effect ...
Deschele Schilder's user avatar
2 votes
1 answer
139 views

Is there a minimum distance between two black holes in a binary system beneath which it can't be observed as a binary?

Suppose two black holes are observable by means of their lensing effect. If these holes are orbiting around each other, then is there a minimum distance from each other to be still observable as ...
Deschele Schilder's user avatar
-2 votes
2 answers
157 views

Could observation of GL or other image phenomena from system of 2 merging massive dense objects and of GW caused by their merge be connected?

What is the probability to observe gravitational lensing (or any other image related phenomena) from the pair of black holes (or pair of neutron stars or black hole - neutron star) which are about to ...
Alex's user avatar
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How well conserved is etendue in extreme gravitational lensing scenarios?

This excellent answer to Could dark matter exist in the Universe in the form of sufficiently dense objects? includes the following image and description: Light from the background galaxy circles a ...
uhoh's user avatar
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Would the stars look different if many primordial black holes were present?

Suppose that there are many primordial black holes. These are point masses which have a small probability to collide with stars let alone themselves. They are formed in the early universe and could ...
Deschele Schilder's user avatar
3 votes
1 answer
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Lightest object so far to function as gravitational lense?

Many amazing discovers are based on gravitational lensing and microlensing, but as non-expert it is not obvious to me: What is the (current) lower mass limit of the lensing object(s) for which ...
B--rian's user avatar
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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 ...
2080's user avatar
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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 ...
bea's user avatar
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Is GAIA the only game in town for looking at quadrupole gravitational deflection of light?

From Gerry Gilmore (2018) Gaia: 3-dimensional census of the Milky Way Galaxy 4.4 Fundamental physics Relativistic effects are highly significant for Gaia measurement accuracy, with tests of General ...
uhoh's user avatar
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Has GAIA learned anything about General Relativity looking near Jupiter? (Gerry Gilmore: "oblate rotating mass moving in a deeper (Solar) potential")

From Gerry Gilmore (2018) Gaia: 3-dimensional census of the Milky Way Galaxy 4.4 Fundamental physics Relativistic effects are highly significant for Gaia measurement accuracy, with tests of General ...
uhoh's user avatar
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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 "...
uhoh's user avatar
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7 votes
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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 ...
uhoh's user avatar
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Can the lensing effect of Sagittarius A* be used to image the stars diametrically opposite to the sun?

The sun can magnify an image of a source 100 ly away nearly 100 billion times, if the ring is captured from the nearest focal point (550AU). According to Christian Ready of Launch Pad Astronomy, we ...
Akash Ghoshal's user avatar
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1 answer
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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?
user287933's user avatar
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1 answer
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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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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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