Astronomers from Tokyo Discover Ancient Massive Galaxies

Astronomers from the University of Tokyo have discovered massive ancient galaxies using the combined power of several astronomical observatories.
Donna Fuscaldo

Using the combined power of several astronomical observatories spanning the globe, astronomers in Tokyo were able to discover ancient massive galaxies that are connected via supermassive black holes.

It marks the first multiple discoveries in history with the combined observatories trumping the access the Hubble Space Telescope has given the world.


First time that massive galaxies were confirmed

 "This is the first time that such a large population of massive galaxies was confirmed during the first 2 billion years of the 13.7-billion-year life of the universe. These were previously invisible to us," said researcher Tao Wang of the Institute of Astronomy at the University of Tokyo in a press release announcing the discovery. "This finding contravenes current models for that period of cosmic evolution and will help to add some details, which have been missing until now."

While the Hubble Space Telescope has given astronomers an unprecedented view of outer space, it has blind spots that the astronomers wanted to overcome. Suspecting there were things in deep space that couldn't be seen by the Hubble the astronomers turned to newer generations of observatories to reveal what they suspected.

The distance makes it hard to see the galaxies 

While these 39 galaxies are massive in size, Professor Kotaro Kohno, who was also part of the research team, said the light from the galaxies are very faint making it invisible to human eyes and undetectable by the Hubble. Astronomers said that even though these galaxies were the largest of their time the immense distance made the light stretch. The amount of stretching the light undergoes enables astronomers to determine how far away something is and how long ago the light was emitting from the galaxies. 

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"It was tough to convince our peers these galaxies were as old as we suspected them to be. Our initial suspicions about their existence came from the Spitzer Space Telescope's infrared data," said Wang. "But ALMA has sharp eyes and revealed details at submillimeter wavelengths, the best wavelength to peer through dust present in the early universe. Even so, it took further data from the imaginatively named Very Large Telescope in Chile to really prove we were seeing ancient massive galaxies where none had been seen before."

Implications of Discovery Just Being Realized 

The astronomers said the galaxies also appeared to be weak because bigger galaxies tend to be covered in dust which makes them appear smaller than other galaxies. Since this was the first discovery of a population of ancient galaxies, the implications of their work are just now being realized. 

"These gargantuan galaxies are invisible in optical wavelengths so it's extremely hard to do spectroscopy, a way to investigate stellar populations and chemical composition of galaxies. ALMA is not good at this and we need something more," concluded Wang. "I'm eager for upcoming observatories like the space-based James Webb Space Telescope to show us what these primordial beasts are really made of." 

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