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Galaxies have aligned for 10 billion years

Most galaxies are randomly oriented in space, but the biggest ones often point toward their neighbors. A new study traces these alignments back into the early universe.

A foreground star and distant galaxies, via ESA/Hubble, NASA, HST Frontier Fields.

Astronomer Michael West of Lowell Observatory in Flagstaff, Arizona and a team of collaborators from Finland and the UK recently observed 65 giant and very distant galaxies with the Hubble Space Telescope. The team found that the most massive galaxies were already aligned with their surroundings when the universe was only one-third of its current age. Thus the new study suggests the most massive galaxies in our universe have been aligned with their surroundings for at least the past 10 billion years. It is the furthest back in time that this phenomenon has been seen. Results of this new study were published online on June 12, 2017 by the peer-reviewed journal Nature Astronomy.

Most galaxies are randomly oriented in space, but astronomers have long known that the biggest ones often point towards their neighbors. When and how these alignments occurred remains a mystery. West said in a statement from Lowell Observatory that the new research:

… is an important new piece of the puzzle because it says that whatever caused these alignments happened early.

The statement explained:

There are different theories for why such alignments occur. One is that giant galaxies grow by accreting smaller neighbors along preferred directions that reflect the cosmic web, a vast network of filaments connecting galaxies on large scales. Another theory suggests that, given enough time, gravity’s relentless tug will slowly reorient the largest galaxies until they are aligned with the surrounding distribution of galaxies. While the discovery of galaxy alignments at early epochs does not rule out either scenario, it does place increasingly tight time constraints.

West and team said they want to look further into the past by observing more remote galaxies. They want to see if there was a time before such massive galaxies were aligned. However, they said, studying galaxies at the dawn of time is not easy, even with Hubble. According to West:

We’re trying to measure the shapes and orientations of galaxies that appear very faint and very small because of their great distances, which is challenging.

Bottom line: A new study suggests the most massive galaxies in our universe have been aligned with their surroundings for at least the past 10 billion years.

Via Lowell Observatory

Deborah Byrd

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