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Fraser
2006-May-24, 04:44 AM
SUMMARY: The most powerful telescopes in the Universe are relatively nearby galaxies, which warp and focus the light of more distant objects. Called gravitation lenses, which occur randomly, are a boon for astronomers as they allow powerful telescopes, like Hubble, to look even further out into the Universe. This Hubble image is the first "quintuple quasar" ever seen, where an entire galaxy perfectly focuses a more distant quasar - located 12 billion light-years away.

View full article (http://www.universetoday.com/am/publish/hubble_best_lens.html)
What do you think about this story? post your comments below.

fencewalker
2006-May-24, 05:47 PM
After looking at this image I am completely confused. Where are the 5 images of the quasar? Can someone draw arrows and post the new image? Or even try to explain where they are at? I would love to be able to see this so I can understand it a little better.

ngc3314
2006-May-24, 05:55 PM
After looking at this image I am completely confused. Where are the 5 images of the quasar? Can someone draw arrows and post the new image? Or even try to explain where they are at? I would love to be able to see this so I can understand it a little better.

The quasar images are marked on this image (http://hubblesite.org/newscenter/newsdesk/archive/releases/2006/23/image/b) from Hubblesite. One additional note of interest is that the fifth, almost central, quasar image is seen. Most galaxy mass distributions give an odd number of images, but the last one is demagnified and usually too faint to see against the light of the lens galaxy.

fencewalker
2006-May-24, 06:00 PM
Thank you. I thought those were the quasar images but I wasn't sure.

jimmarsen
2006-May-25, 02:22 PM
Is there an easy way to tell if a galaxy or quasar image is the actual object or a "false" image produced by gravitational lensing? It it possible that some percentage of cataloged objects are actually these "false" images? Also, if gravitational lensing can distort the positions and magnitudes of real images, has this been factored in to maps of the sky?

antoniseb
2006-May-27, 06:09 PM
There are very few maps of the sky that are so accurate that they will take this gravitational lensing into account. I am under the impression that the GAIA probe will be so accurate that it will need to take gravitational lensing from the Sun into account, but aside from that, probably nothing else.

jimmarsen
2006-May-28, 01:38 AM
There are very few maps of the sky that are so accurate that they will take this gravitational lensing into account. I am under the impression that the GAIA probe will be so accurate that it will need to take gravitational lensing from the Sun into account, but aside from that, probably nothing else.

Are you saying the effect on magnitude and position from galaxies and galaxy clusters is below the margin of error and can be ignored?

What about "false" images? Are they so rare that they can be ignored? Or are they so obvious that that are easily subtracted in surveys? If so, how is that determined?

antoniseb
2006-May-28, 11:50 AM
Perhaps I misunderstood what you were saying. As far as these images of lensed galaxies are concerned, we catalog the apparent location of each image as a separate object located where we see it. Some special studies MAY determine the actual direction, but there are so few of these that it is not disrupting any statistical countings we do.

Jerry
2006-May-30, 04:09 AM
Whereas there are so few of these objects known, the supernova event is very important...single event statistics mean exactly nothing, but one more lensed galaxy producing a supernova at a similar distance would be a likely indicator that the distant supernova rate is higher than what we are able to observe without the aid of a gravitational lens.

jimmarsen
2006-May-30, 06:55 PM
Perhaps I misunderstood what you were saying. As far as these images of lensed galaxies are concerned, we catalog the apparent location of each image as a separate object located where we see it. Some special studies MAY determine the actual direction, but there are so few of these that it is not disrupting any statistical countings we do.

How is it determined that an image is real and not a "false" image caused by the lensing effect?

The other part of my question had to do with distant real images whose light passes near the outer boundary of a foreground cluster. Is it true that this would not generate "false" images but that the lens effect could distort the true position of the more distant object? Could the apparent magnitude also be affected?

antoniseb
2006-May-30, 07:25 PM
1. How is it determined that an image is real and not a "false" image caused by the lensing effect?
2. The other part of my question had to do with distant real images whose light passes near the outer boundary of a foreground cluster. Is it true that this would not generate "false" images but that the lens effect could distort the true position of the more distant object?
3. Could the apparent magnitude also be affected?

1. These "false" images are rare. Only a microscopic fraction of the observed galaxies could be duplicate images.

2. Many galaxies are weakly lensed. Their image is slightly distorted, and their light-path to us is slightly curved.

3. The apparent magnitude of a weakly lensed galaxy will not be radically different than if it were not lensed at all, but it will be a little different.