Hubble Finds Double Einstein Ring

Einstein Duble brings us news that astronomers using the Hubble Telescope have discovered an extremely rare double Einstein Ring. Occasionally, galaxies or other bright objects are located in such a way that they are behind another galaxy when viewed from Earth. When light from the further galaxy passes a sufficiently massive closer galaxy, the path of the light is bent inward from all sides, creating a "ring" effect. In this case, not one, but two galaxies are directly behind the foreground galaxy, so the gravitational lens produces two distinct rings. Quoting Presscue: "The distribution of dark matter in the foreground galaxies that is warping space to create the gravitational lens can be precisely mapped. In addition, the geometry of the two Einstein rings allowed the team to measure the mass of the middle galaxy precisely to be a value of 1 billion solar masses. The team reports that this is the first measurement of the mass of a dwarf galaxy at cosmological distance (redshift of z=0.6)."

Re:Yay Hubble

[stoolpigeon]

That upgrade is on hold. The problems that knocked the latest Atlantis mission back into February have jacked up the schedule. So it was planned for August but now it will be later [reuters.com]. I would think that with eol for the shuttle and hubble both rapidly approaching - any more problems or serious delays and it could get knocked from on hold to canceled.

You forgot about mass too

[Loki P]

And the other problem is the masses of all the galaxies are different. The dwarf galaxy wouldn't act as a lens for them in the same way that the massive galaxy does for us.

non-slashdotted hubble double ring article(w/pics)

[hxnwix]

Another article on this double ring find. [spacetelescope.org]

Re:Precise

[osu-neko]

There's a great story about the first person to accurately measure the height of Mount Everest, whose name escapes me at the moment.

Sir Andrew Scott Waugh. He also gave the mountain its English name.

Re:Propaganda

[rush22]

"The distribution of dark matter in the foreground galaxies that is warping space to create the gravitational lens can be precisely mapped." Really? How can we "precisely map" something that we have never even shown positively to exist yet? The distribution of gravity could be caused my a number of things other than "dark matter". Gravitational disturbance by itself is not evidence for dark matter, any more than it supports at least several other hypotheses.

Yes it is kind of like propaganda to assume dark matter theory is right, but that's the best theory there is. "Dark matter" is just a name for "whatever causes these observations." Whatever it is looks and acts like a gravitational field. Mass produces a gravitational field, so it's assumed to there's some sort of invisible mass, some sort of "dark matter." And they can still "precisely map" the gravitational field, regardless of what is causing it.

And unless you know something physicists don't know, there's not a "number of things" that could cause a gravitational field like that. Interestingly, there is another theory, ether theory [nationalgeographic.com], but even the physicist who came up with it says: "We're offering an alternative to the dark matter theory--we're not saying it's wrong. If I had to bet today on which of these theories was correct, I might bet on dark matter."

Re:Could someone please explain?

[Hatta]

Light always travels in straight lines. Or to put it another way, light always travels the shortest path from A to B. Or to put it another way, light always travels every path from A to B, but they all cancel each other out except the shortest path. (read Feynman's QED for more) So it can't be curving the light, because that would make the path longer.