ALMA’s Long Baseline Campaign has produced a spectacular image of a distant galaxy being gravitationally lensed. Image via NASA/ALMA

When Einstein first devised his theories of general and special relativity, they were accompanied by many predictions. One prediction was gravitational lensing. If you aren’t familiar with this phenomena, it essentially deals with gravity and the effect this force has on the fabric of spacetime and on light itself. When something of sufficient mass forms, like a supercluster, for instance, the fabric of space is warped so strongly that, when light passes through this region relative to Earth, objects in the background are magnified by several magnitudes—hence the ‘lensing’ part.

Over the years, this feature of relativity has been proven over and over again. Most recently, researchers with NASA used gravitational lensing to glimpse a distant supernova not once, but four different times. Now, astronomers from the European Southern Observatory (ESO) have done it once again—this time using ALMA’s Long Baseline Campaign.

The distant galaxy, called HATLAS J090311.6+003906 (otherwise known as SDP.81), is unlike anything we’ve ever found in terms of quality and detail (especially when distance is factored in). ALMA, which imaged the protoplanetary disk of a star just last year, has certainly outdone itself. It clearly resolves star forming clumps and HII regions—the ESO compares them to “giant versions of the Orion Nebula.”

Ultimately, the lensing effect seen with SDP .81 has created a bizarre circular-structure known as an Einstein Ring. The images alone have yielded quite a bit of information pertaining to the galaxy–including “structure, contents, motion, and other physical characteristics.”

A so-called Einstein ring (Image via ESA/Hubble & NASA)

As the ESO notes:

The researcher also conducted a spectral analysis of SDP.81, which allowed them to infer its mass and rotation. This, in turn, helped them determine that the galaxy may soon experience a starburst period. Moreover, based on the inherent instability of the galaxy’s supply of gas, it would seem as if this new era of star formation will begin sooner rather than later.

Another fascinating, final bit of information, points to the existence of a supermassive black hole looming in the central nucleus of the foreground galaxy (the one providing the gravitational lense)—weighing between 200 and 300 million solar masses.

“The number of papers published using this single ALMA dataset demonstrates the excitement generated by the potential of the array’s high resolution and light-gathering power. It also shows how ALMA will enable astronomers to make more discoveries in the years to come, also uncovering yet more questions about the nature of distant galaxies,” they said.


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