Chuck Bednar for redOrbit.com – @BednarChuck
Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the natural phenomenon known as gravitational lensing for enhanced magnification, a team of researchers has observed a monstrous galaxy located near the edge of the known universe in unprecedented detail.
While conducting high-resolution test observations last October, ALMA imaged a galaxy called SDP.81, which is located 11.7 billion light years from Earth in the constellation Hydra. Its image was magnified with a gravitational lens created using a massive foreground galaxy located about 3.4 billion light years from Earth.
The lensing effects made the galaxy look brighter, but it also caused it to be smeared into a ring shape. In the new study, however, Yoichi Tamura and Masamune Oguri, assistant professors at the University of Tokyo managed to correct the lensing effects to get a better picture of the galaxy.
They found that SDP.81 is home to a massive amount of star formations, with new stars being born at rates up to thousands of times faster than in the Milky Way. They also found that the center of the foreground galaxy is home to a supermassive black hole. A paper detailing their work appears in the Publications of the Astronomical Society of Japan.
Enhancing ALMA to get a closer look inside SDP.81
The authors explained that the discovery is an important step forward in improving our understanding of how starburst galaxies evolve, as well as the characteristics of supermassive black holes in galaxies. They also noted that this would not have been possible without the use of gravitational lensing to enhance ALMA’s already high sensitivity and resolution.
The study authors explained that, according to Einstein’s theory of General Relativity, massive objects bend space and time, and the light travelling through this space-time curvature tends to follow the curve, functioning like a massive lens. This phenomenon makes distant objects look far larger and brighter, making them easier for astronomers to study.
When a foreground galaxy lines up perfectly in between a distant one and the Earth, the image forms a circle of light called an Einstein ring. SDP.81 is a perfect example of this, and the natural enhancements allowed ALMA to detect radio waves with a one-millimeter wavelength that had been emitted by cold molecular dust and gas.
These particles, which are part of forming stars, were captured in a higher resolution than is even possible with the Hubble telescope (23 milliarcseconds). This allowed Tamura, Oguri, and their fellow researchers to locate found bends, branches, and tiny grain-like structures within the ring. To understand the causes of those structures, they made a detailed model of the gravitational lens that allowed them to precisely adjust it to correct for various distortions.
Molecular clouds, supermassive black hole discovered
Using their model, the astronomers found that the fine structures in the ring reflect SDP.81’s inner structure and revealed the presence of what they believe are areas of new star and planet formations called giant molecular clouds. These clouds are similar in size to those found in the Milky Way, and this discovery marks the first time that scientists have been able to uncover the inner workings of a galaxy so far away from the Earth.
In addition, the image helped the researchers conclude that the foreground galaxy used in the gravitational lensing process is home to a black hole more than 300 million times more massive than the sun. They came to this conclusion due to the fact that the mass of the galaxy’s black hole causes the more distant galaxy to appear far fainter in the image, and since SDP.81 is not very bright in the image, they determined that this must be the reason why.
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