Space Warps Talk

Two sims and a real lens ?

  • ElisabethB by ElisabethB moderator

    The two at the top are sims.
    But what about the faint blue arc underneath the two ellipticals?

    Posted

  • Tom_Collett by Tom_Collett scientist

    The faint one looks like a good candidate to me!

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  • Capella05 by Capella05 moderator

    Same here 😃

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  • AlexandredOr by AlexandredOr

    I think that your title is correct : 2 sims and a real lens 😉

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  • ElisabethB by ElisabethB moderator

    Yippee ! 😄

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  • drphilmarshall by drphilmarshall scientist, admin

    Crikey 😃 This one is going to make @anupreeta laugh!

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  • Tom_Collett by Tom_Collett scientist

    The clever way that simulated lenses are chosen means that real candidates have a higher probability of being in a frame with a simulated image than in a random image. The robot tries to put simulations in the most realistic place possible i.e. near things that it thinks are massive galaxies or clusters of galaxies. Massive galaxies are clustered on the sky because they are clustered in space. So if there is a sim, there's a good chance that other potential lenses are lurking nearby.

    That said, this frame is brilliantly unlikely!

    This is another (less convincing) case of 2 sims plus one maybe: ASW0001gae

    This all makes me slightly worried that some of the simulations may actually obscure real, fainter, lenses. Keep your eyes peeled...

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  • ElisabethB by ElisabethB moderator

    This all makes me slightly worried that some of the simulations may actually obscure real, fainter, lenses. Keep your eyes peeled...

    I know what you mean ! If I see a very obvious lens I'm less likely to search the frame for other (fainter) lenses; Well,I was until now ! 😉

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  • drphilmarshall by drphilmarshall scientist, admin

    I added this one to the #simfail list, and we can look into rejecting close pairs of lens galaxies before we add the arcs.

    The original plan was to have around 4500 sims, but Tom's right, at that rate a very few of those (4-5?) would have sim arcs appearing on top of real ones! (Some of which will be known already.) That would indeed be a shame. Let's see if we can think of a workaround. The issue is that @anupreeta needs to be able to sample the selection function well, by including sims witha range of physical properties. Would we trade a well-understood selection function for a one or two more lenses? I'm not sure - maybe not. The selection function is really important!

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  • Tom_Collett by Tom_Collett scientist in response to drphilmarshall's comment.

    Can't you show the training frames sometimes with and sometimes without the simulation?

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  • drphilmarshall by drphilmarshall scientist, admin

    Yes, I think so. Anu's on the case, adjusting the data inputs.

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  • JasonJason by JasonJason

    Here is one sim and a possible real arc, what is the verdict?

    ASW00015bc

    enter image description here

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  • Capella05 by Capella05 moderator in response to JasonJason's comment.

    Hi JasonJason,

    You need to post the ID of the image - as we have no way of linking back to the original from the static image you have posted 😃

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  • Tom_Collett by Tom_Collett scientist

    What about this sim? ASW00016ef There's blue fuzz under it, but I can't tell if it'll be a lens or not.

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  • JasonJason by JasonJason

    Image is ASW00015bc

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  • JasonJason by JasonJason

    I just got this same one
    enter image description here

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