APOD: The Einstein Cross Gravitational Lens (2010 Feb 07)

[APOD Robot]

The Einstein Cross Gravitational Lens

Explanation: Most galaxies have a single nucleus -- does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. The central cloverleaf is rather light emitted from a background quasar. The gravitational field of the visible foreground galaxy breaks light from this distant quasar into four distinct images. The quasar must be properly aligned behind the center of a massive galaxy for a mirage like this to be evident. The general effect is known as gravitational lensing, and this specific case is known as the Einstein Cross. Stranger still, the images of the Einstein Cross vary in relative brightness, enhanced occasionally by the additional gravitational microlensing effect of specific stars in the foreground galaxy.

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[Arninetyes]

What I find a bit interesting about this photograph is the apparent similarity between this image of an Einstein cross and a uniaxial interference figure, as seen in thin section between crossed polar filters. Of course, it is formed completely differently. The Einstein cross results from quadruple replication of the lensed quasar, while a uniaxial cross is formed by extinction of light within the cross.

[MadCat-75]

Hi,

why is there a cross and no ring/circle of light?

sincerely yours,

Heiko

[neufer]

why is there a cross and no ring/circle of light? sincerely yours, Heiko

Einstein rings and frictionless pulleys only exist in an idealized Platonic world.

<<In observational astronomy an Einstein ring is the deformation of the light from a source (such as a galaxy or star) into a ring through gravitational lensing of the source's light by an object with an extremely large mass (such as another galaxy, or a black hole). This occurs when the source, lens and observer are all aligned. The first complete Einstein ring, designated B1938+666, was discovered by collaboration between astronomers at the University of Manchester and NASA's Hubble Space Telescope in 1998.



Hundreds of gravitational lenses are currently known. About half a dozen of them are partial Einstein rings with diameters up to an arcsecond, although as either the mass distribution of the lenses is not perfectly axially symmetrical, or the source, lens and observer are not perfectly aligned, we have yet to see a perfect Einstein ring. Most rings have been discovered in the radio range.>>

[neufer]

<<It has been estimated that there are approximately 10,000 three-leaf clovers for every four-leaf clover. It is debated whether the fourth leaflet is caused genetically or environmentally. Its relative rarity suggests a possible recessive gene appearing at a low frequency. Alternatively, four-leaf clovers could be caused by somatic mutation or a developmental error of environmental causes. They could also be caused by the interaction of several genes that happen to segregate in the individual plant. It is possible all four explanations could apply to individual cases.

Certain companies produce four-leaf clovers using different means. Richard Mabey alleges, in Flora Britannica, that there are farms in the US which specialize in four-leaf clovers, producing as many as 10,000 a day (to be sealed in plastic as "lucky charms") by feeding a secret, genetically-engineered ingredient to the plants to encourage the aberration (there are, however, widely-available cultivars that regularly produce leaves with multiple leaflets) . Mabey also states that children learn that a five-leaved clover is even luckier than a four-leaved one. Five-leaf clovers are less commonly found naturally than four-leaf clovers; however, they, too, have been successfully cultivated.>>

<<"The Luck of the Fryrish" is the fourth episode in season three of Futurama. It originally aired in North America on March 11, 2001. The episode opens in the mid-1970s, where a young Yancy Fry is jealous of his newborn brother Philip, and copies him in anything he can. In the year 3000, Fry is getting fed up with his bad luck in a horse rally. In a flashback, Fry discovers a seven-leaf clover, which grants him extraordinary luck and allows him to beat his brother in any contest, from basketball to breakdancing. Fry sets off, with Turanga Leela and Bender, to find his clover in the ruins of Old New York and makes his way to his old house.

Back in the 1980s, a teenage Fry hides the seven-leaf clover inside his Ronco record vault in his copy of The Breakfast Club soundtrack. In the year 3000, Fry remembers the combination, but when the safe is stuck, Bender opens it up for him. Unfortunately, Fry discovers that the clover is missing, concluding that Yancy must have stolen it. They happen across a statue of whom they believe to be Yancy, with the seven-leaf clover in his lapel. The inscription: “Philip J. Fry - First person on Mars” angers Fry because he believes Yancy stole his name and his dream.

"That clover helped my rat-faced brother steal my dream of going into space."

• 

Professor Farnsworth pulls up a biographical movie about “Philip J. Fry,” where the crew learns that he was a millionaire rock star astronaut, and is now buried (with the seven-leaf clover) in Orbiting Meadows National Cemetery, a graveyard orbiting Earth. A furious Fry sets off to rob Philip J. Fry's grave and recover the clover. The story jumps back to the early 21st century, where an adult Yancy is rummaging through his missing brother’s music to find something to play at his wedding. Yancy discovers the seven-leaf clover and takes it.

Fry, Leela and Bender reach the grave site, and start digging, but Fry knocks loose some moss that is covering part of an inscription on Yancy's tombstone, and begins to read. The story jumps back to Yancy, who is discussing naming his newborn son with his wife. Yancy didn't keep Fry's clover; instead, he gave it to his newborn son and named him Philip J. Fry II. The inscription on the tomb reads “Here Lies Philip J. Fry, named for his uncle, to carry on his Spirit.” Bender finds the clover, and he offers to mess up the corpse, but Fry returns the clover to his nephew’s grave as "Don't You (Forget About Me)" by Simple Minds (from the Breakfast Club soundtrack) rolls over the end credits.>>

[Case]

Imaged by the 3.5-meter (138") WIYN Telescope on Kitt Peak (Google Maps).

Also known as "Huchra's Lens", the quasar is often referenced as Q2237+0305, while the galaxy is cataloged as CGCG 378-015 G (Catalogue of Galaxies and of Clusters of Galaxies) and PGC 069457 (Principal Galaxy Catalog).

The Einstein Cross does not show in a DSS2 image (RA 22h40m30.241s, Dec +03d21m30.92s).
The APOD image makes it seem like the quasar outshines the galaxy, but the DSS2 image shows a rather regular galaxy image without super-bright portions. Is that just resolution, or is the quartet enhanced in the APOD?

[Chris Peterson]

The Einstein Cross does not show in a DSS2 image (RA 22h40m30.241s, Dec +03d21m30.92s).
The APOD image makes it seem like the quasar outshines the galaxy, but the DSS2 image shows a rather regular galaxy image without super-bright portions. Is that just resolution, or is the quartet enhanced in the APOD?

The resolution is so low in the DSS2 image compared with the WIYN image that the lensed quasar components are completely unresolved. I'd say that what you're interpreting as the galaxy core in the DSS2 image is, in fact, the lensed quasar, and it does outshine the galaxy.

[BMAONE23]

The Einstein Cross does not show in a DSS2 image (RA 22h40m30.241s, Dec +03d21m30.92s).
The APOD image makes it seem like the quasar outshines the galaxy, but the DSS2 image shows a rather regular galaxy image without super-bright portions. Is that just resolution, or is the quartet enhanced in the APOD?

The resolution is so low in the DSS2 image compared with the WIYN image that the lensed quasar components are completely unresolved. I'd say that what you're interpreting as the galaxy core in the DSS2 image is, in fact, the lensed quasar, and it does outshine the galaxy.

It looks to me like the Lensed Quasar would be over exposed to enhance (brighten) the fainter spiral structure as is noted in the attached image vs the APOD. That, coupled with a lower resolution image, bleeds the "Cross" together into the Bloby appearance of the core.

[emc]

I’m always amazed at what astronomers can extrapolate from our distant space objects.

What data for instance helps astronomers determine this APOD to be the gravitational lensing of the distant quasar Q2237? Is it just the redshift match for all four images and the relational color and brightness variation? Not that more data is needed but I wonder if there are other measurements that help? Say can we determine composition to match as well?

[emc]

[youtube]http://www.youtube.com/watch?v=yamVbK-J ... re=related[/youtube]

[elipongo]

Einstein's Cross??? The man was Jewish! Is this an official name? I would vote for it to be named Einstein's Square or something else less incongruous.

I realize that many astronomers are agnostic, but can I really be the only person who finds this annoying?

~ Elias Friedman

[bystander]

http://en.wikipedia.org/wiki/Einstein_Cross

[Chris Peterson]

Einstein's Cross??? The man was Jewish! Is this an official name? I would vote for it to be named Einstein's Square or something else less incongruous.

Einstein may have had a Jewish heritage, but he was pretty obviously an atheist by most definitions- at the very least, he had no conventional religious convictions. So I don't think he'd much mind!

In any case, the shape is very appropriately called a "cross"- a geometric shape that has no intrinsic religious significance. It isn't called a "Latin cross", which is an important symbol for Christians. Nor a Coptic cross, Greek cross, swastika, or any of the dozens of other specific crosses that usually have symbolic meaning.

[bystander]

The cross is not necessarily a Christian symbol. The cross precedes the Christian faith.

[elipongo]

I speak not of the geometrical figure, but rather about the word itself. Cross derives from the Latin Crux, a wooden frame used for executions. In modern usage, when paired with a possessive proper noun it refers to either a piece of religious jewelry or burdensome obligation a person has.

And considering that the old Christian blood libels served as the foundation for the Nazi persecutions that forced Einstein to leave his home in Germany, I DO think he might have reservations about this name.

~ Elias Friedman

[bystander]

However, Einstein Cross does refer to the geometrical figure.

The Einstein Cross or Q2237+030 or QSO 2237+0305 is a gravitationally lensed quasar that sits directly behind ZW 2237+030, Huchra's Lens.
It is quadruply imaged, hence its name, Einstein Cross, forming a nearly perfect cross, with the lensing galaxy at its center.

[Chris Peterson]

I speak not of the geometrical figure, but rather about the word itself. Cross derives from the Latin Crux, a wooden frame used for executions.

Etymology is irrelevant. In modern usage, outside any symbolic context, a cross is a geometrical shape. It's as simple as that. In this case, the lensed quasar forms a cross.

Einstein would be supremely excited by the observation of an actual gravitational lens, and presumably honored to have one that carries his name. The very idea that its description as a "cross" would offend him, or should offend anybody, is pretty silly IMO.

[emc]

From what reading I've done regarding Einstein, I don’t expect he would have been cross.

[Andy Wade]

Last time I looked Einstein was dead, so there's no need to be annoyed on his behalf. That his name is associated with an amazing natural phenomenom is a tribute rather than an annoyance. I wish they'd name something after me.

[neufer]

Einstein's Cross??? The man was Jewish! Is this an official name? I would vote for it to be named Einstein's Square or something else less incongruous.

Einstein may have had a Jewish heritage, but he was pretty obviously an atheist by most definitions- at the very least, he had no conventional religious convictions. So I don't think he'd much mind! In any case, the shape is very appropriately called a "cross"- a geometric shape that has no intrinsic religious significance. It isn't called a "Latin cross", which is an important symbol for Christians. Nor a Coptic cross, Greek cross, swastika, or any of the dozens of other specific crosses that usually have symbolic meaning.

Corpus Hypercubus

[emc]

Einstein's rendition of the Crooked Cross...

[TelescopicView]

The Einstein Cross Gravitational Lens

Explanation: Most galaxies have a single nucleus -- does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this essay . The central cloverleaf is rather light emitted from a background quasar. The gravitational field of the visible foreground galaxy breaks light from this distant quasar into four distinct images. The quasar must be properly aligned behind the center of a massive galaxy for a mirage like this to be evident. The general effect is known as gravitational lensing, and this specific case is known as the Einstein Cross. Stranger still, the images of the Einstein Cross vary in relative brightness, enhanced occasionally by the additional gravitational microlensing effect of specific stars in the foreground galaxy.

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Hey APOD,

I am pretty new to astronomy, just kind of been studying on my own for the past few months so this post is a bit confusing for me. Is there any way you would be willing to come back to this thread and try to explain the four nucleus phenomena we see in a little bit more simple terms, I am having a hard time grasping all of the terminology. Thank you so much.

R