ALMA Captures Ancient Galaxy's Near-Perfect Einstein Ring

This is one of the finest examples of an Einstein ring spotted to date, but it wasn't observed by the Hubble Space Telescope, this stunning example of general relativity in action was captured by the world's most powerful ground based observatory.

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Located in Chile's Atacama Desert, the Atacama Large Millimeter/submillimeter Array (ALMA) has recently gone online and astronomers are beginning to realize its powerful potential.

As part of the ALMA Long Baseline Campaign that was carried out at the end of 2014 when the observatory's antennae were at their widest separation of 15 kilometers (9.3 miles), this ancient galaxy was spotted. Warped by a massive foreground galaxy, the light from the ancient galaxy called SDP.81 (that was forming when the universe was 15 percent the age it is now) has been bent around the warped spacetime.

Made famous in Hubble observations, gravitational lenses are fairly common, where distant sources of light become warped around massive objects such as galactic clusters. Bright arcs are often seen and, if the configuration is just right, these arcs turn into circles creating stunning Einstein rings, as this ALMA example shows.

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Most recently, Hubble's powerful optics have been supplemented by these natural lenses, helping us see even further into the cosmos - a survey project called "Frontier Fields." In many cases, the arcs of distant galactic light have been de-warped and pieced back together so we can gain a unique look at galaxies that would otherwise be out of view from even the most powerful space telescope.

But this near-perfect ring wasn't captured by Hubble, ALMA has boosted the resolution of this ring, revealing never-before seen detail in this young star-forming galaxy.

The beauty of long-baseline interferometers (such as ALMA) is that individual antennae can be spaced far apart, simulating a collecting area of that baseline distance. In other words, ALMA is simulating a collecting dish 15 kilometers wide, boosting our observational potential, overshadowing the biggest space-based telescope mirror.

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SDP.81 wasn't the only target in ALMA's Long Baseline Campaign. The observatory also studied the star Mira, asteroid Juno, quasar 3C138 and the amazing protoplanetary disk surrounding HL Tauri. And this is just a taste of things to come from an awesome observatory that is shedding new - and finely detailed - light on our cosmos.

Source: ESO

This ALMA observation of the ancient star-forming galaxy SDP.81 is the most detailed example of an Einstein ring to date.

The Atacama Large Millimeter/submillimeter Array (ALMA) is finally complete, after the project's final 12-meter antenna was handed over on Sept. 30, 2013. The 66th dish, shown here, is the last of 25 European-built instruments. The Joint ALMA Observatory (JAO) is a collaboration between the European Southern Observatory (ESO), the National Radio Astronomy Observatory (NRAO) and the National Astronomical Observatory of Japan (NAOJ).

All 66 millimetre/submillimetre-wave radio antennas are expected to be operational by the end of 2013, working together as one large telescope. ALMA will operate as an interferometer, spread over 16 kilometers of the Chajnantor Plateau in the Atacama Desert, Chile.

ALMA is sensitive to millimetre and submillimetre wavelengths, between infrared light and radio waves in the electromagnetic spectrum, a range that will help astronomers peel back the veil on distant objects in the Cosmos.

The giant antenna transporter, called Otto, delivers the final antenna to the array on Sept. 30, 2013.

The final dish was built by the European AEM Consortium, the largest of the project's contracts. North America delivered 25 12-meter antennas and East Asia delivered 16 (four 12-meter and twelve 7-meter).

"This is an important milestone for the ALMA Observatory since it enables astronomers in Europe and elsewhere to use the complete ALMA telescope, with its full sensitivity and collecting area," said Wolfgang Wild, the European ALMA Project Manager.

An artist's impression of the complete ALMA array in the Atacama Desert.

Possibly breaking the record for altitude record for a radio controlled hexacopter, this aerial photograph of ALMA in the extreme environment of the Atacama Desert in Chile was taken earlier this year.