More Giant Galaxies Discovered in the Early Universe

Image: Artist's concept via NRAO/ AUI/ NSF; D. Berry.

 Astronomers using the Atacama Large Millimeter/millimeter Array (ALMA) in Chile have discovered two giant galaxies that existed when the universe was only 780 million years old, or about 5 percent of its current age. These two galaxies, known collectively as SPTO311-58, appear to be within an even-more-massive dark matter halo, containing several trillion times the mass of our sun.
 This discovery is quite surprising for scientists. Like how suns and planets are formed from clumps of gas and rock sticking together, astronomers expected the first galaxies to resemble little dwarf galaxies such as those seen today. Yet, nature has surprised everybody, revealing examples of massive galaxies - even for today's standards.

Composite Image via ALMA (ESO/NAOJ/NRAO), Marrone, et al.; B. Saxton (NRAO/AUI/NSF); NASA/ESA Hubble.

 The researchers wrote the following statement: "This ‘de-lensing’ process provided intriguing details about the galaxies, showing that the larger of the two is forming stars at a rate of 2,900 solar masses per year. It also contains about 270 billion times the mass of our sun in gas and nearly 3 billion times the mass of our sun in dust." This shows that these galaxies very likely merged to eventually form the largest galaxy ever observed at that time period in cosmic history.

Read more about this fascinating story at: http://earthsky.org/space/primordial-galaxies-spt0311-58-dark-matter-early-universe