Thousands of Infant Galaxies Discovered Using 3D Universe Map

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The Milky Way galaxy is captured by the NASA Spitzer Space Telescope. Investigating early galaxies can teach us about the likely history of our own. JPL-Caltech/NASA

Astronomers have discovered almost 4,000 galaxies from the dawn of the universe by piecing together a new 3D map of space.

One of the largest maps of the early universe ever created, it offers a window into the history of our own galaxy between 11 and 13 billion years ago.

The research was presented at the European Week of Astronomy and Space Science in Liverpool, UK, and published in two papers in the Monthly Notices of the Royal Astronomical Society.

Light from galaxies very far away takes billions upon billions of years to reach us. This makes telescopes a kind of time machine—the further light has travelled, the older its source must be.

As the universe expands, light from ancient galaxies is stretched, changing its wavelength and making it shine redder. Astronomers can measure this "redshift" to work out how far away something is and how long its light has been traveling for - in other words, how old an object is.

In this study, researchers used telescopes with special filters to "slice the universe in cosmic time and time-travel to the distant past," Sergio Santos, a doctoral student at Lancaster University, U.K., explained in a statement. The team mapped 16 cosmic-time slices from between 11 and 13 billion years ago.

The newly-discovered galaxies hail from the early universe, which scientists believe is now nearly 14 billion years old. Researchers think they can shed light on galaxy formation itself.

"These early galaxies seem to have gone through many more "bursts" when they formed stars, instead of forming them at a relatively steady rate like our own galaxy," astrophysicist David Sobral, also from Lancaster University, said in the statement. "Additionally, they seem to have a population of young stars that is hotter, bluer and more metal-poor than those we see today."

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A map of the cube of spacetime covered in the new survey, showing the distance to the galaxies in billions of light years. The positions of the 4,000 galaxies appear as circles. Their colours represent the degree of redshift seen—bluer circles indicate galaxies nearer to the Earth which are less redshifted. Green, yellow, orange and red circles indicate successively higher redshifts, and galaxies that are progressively further from Earth. D Sobral

As well as being hot, bright, and blue, these galaxies are very compact, with most stretching only about 3,000 light years across. The Milky Way is much bigger, spanning some 100,000 light years in diameter.

"Their compactness likely explains many of their exciting physical properties that were common in the early Universe," added Ana Paulino-Afonso, a doctoral student in Lancaster and Lisbon, in the statement.

By exploring these ancient galaxies, astronomers can piece together some of the likely history of our own galaxy, Paulino-Afonso explained. "Some of these galaxies should have evolved to become like our own," she said, "and thus we are seeing what our galaxy may have looked like 11 to 13 billion years ago."