Space Warps Talk

Types of Lensing

  • Tonibee by Tonibee

    Loving the opportunity to take part in this. Thanks.

    All the educational material is focusing on objects that are lensed by virtue of the fact that light from the background object is stretched around the foreground object. In this example, which I did flag as a candidate, the two blue dots could be foreground objects that are having a squeezing effect on the light.

    The defining characteristics are that squeezing the light means the centre object is the one that appears deformed and not those around the edge, there is a defining line between the objects and there is no arc (or rather it's a hidden, reverse arc).

    That's what troubles me, because the presence of the arc is the defining characteristic in the spotters guide so I'm unsure if this is the type of thing I should be flagging. It's given me a couple of tough decisions already. Are you looking for all examples of light appearing to bend, even when it just a partial overlap of two objects, or just the type in the guide?

    What do you think?

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  • psaha by psaha scientist

    Arcs are the most common observable effect of a space warp, but by no means the only one. LensToy is a nice interactive demo of what you'd see if you put a galaxy behind the gravitational fields of other galaxies. It often shows something rather like the sims on this site 😉

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  • Tonibee by Tonibee

    Thanks psaha! That's really neat and will definitely help.

    Being movable lenstoy really helps to understand the effect we're searching for. It would be great if it were accessible, maybe as a video demo, in the introductory pages.

    Any thoughts on the object I flagged?

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  • psaha by psaha scientist

    I can't mentally classify the object myself. Maybe it's just a chance alignment ... or maybe not...?
    Happy hunting!

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  • JasonJason by JasonJason

    simulated lens

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  • drphilmarshall by drphilmarshall scientist, admin in response to JasonJason's comment.

    Haha - very good! Looks like a sim - but can you post the url of the actual image please? Static images can't be traced... Thanks!

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  • drphilmarshall by drphilmarshall scientist, admin in response to Tonibee's comment.

    It could be a lensed quasar: two blue dots, same colour, arranged closely around an edge-on massive S0 galaxy. Nice catch! The alternative hypothesis (two massive blue objects "squeezing" a background yellow object) is less plausible. Where would the mass be that was doing the lensing?

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  • JasonJason by JasonJason

    ASW000020y is a training image, I think this was because of the out of sync glitch wasn't showing or something, my mistake.

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