Using a new deep learning algorithm and data from the Galaxy Zoo citizen science project, astronomers have discovered 40,000 ring galaxies –six times more than previously known. “There are various ways for rings to form, and this dataset focuses on rings that develop in disk galaxies,” wrote Dr. Brooke Simmons, Galaxy Zoo deputy principal investigator, an astronomer with the University of Lancaster in an email to The Daily Galaxy.
“So, a ring is a feature of a disk, just like a spiral or a bar feature,” Brooke continued her email. “We often see rings with those other disk features, but not always. We think they develop slowly in an undisturbed disk, and are destroyed (or dissipate) when the disk is disrupted by an interaction or a merger. However, disk galaxies are very complex, and it’s difficult to tease out an evolutionary picture for a single feature when you have so many different factors to consider.
“This new sample,” Simmons continued in her email, “is much larger than previously known samples of ring galaxies, and it will be really helpful in allowing us to control for the other considerations in galaxy evolution so that we can understand more about how and why rings develop, and how their presence may affect their host galaxies.”
The images below are of 35 of the ring galaxies newly discovered by the Galaxy Zoo volunteers and the Zoobot. (Credit: Mike Walmsley / Galaxy Zoo collaboration).
“Galaxies live a chaotic life,” said lead author Dr. Mike Walmsley, a postdoctoral researcher at the University of Manchester, applying deep learning research breakthroughs to astrophysics.
“Collisions with other galaxies and bursts of energy from supermassive black holes disrupt the colors and orbits of billions of stars, leaving tell-tale markers that volunteers search for on the Galaxy Zoo website.”
“But understanding exactly which cosmic events lead to which markers requires millions of measured images — more than humans could ever search.”
For their new research, Dr. Walmsley and colleagues used a decade of Galaxy Zoo measurements.
“Galaxy Zoo turns 15 years old this week, and we are still innovating,” said Simmons. “This work will make it possible for a new generation of discoveries to be made from upcoming large galaxy surveys.”
The astronomers created a new deep learning algorithm — named Zoobot — that can not only accurately predict what Galaxy Zoo volunteers would say but understands where it might be mistaken.
“Zoobot is designed to be retrained again and again for new science goals,” they said. “Just like a musician can learn a new instrument faster than their first instrument, Zoobot can learn to answer new shape questions easily because it has already learned to answer more than 50 different questions.”
“Rings take billions of years to form and are destroyed in galaxy-galaxy collisions, and so this giant new sample will help reveal how isolated galaxies evolve,” the authors said. “The dataset will also tell scientists how galaxies age more generally.”
The scientists presented their results this month at the 2022 National Astronomy Meeting (NAM 2022).