Stony Brook University professors helping determine size of universe

It’s hard to fathom the size of the universe. But two Stony Brook University professors are part of a project designed to do just that — an effort scientists say is making advances.

Researchers in the NASA-backed project last week published an article in the journal Science detailing their work, which was done largely with the Hubble Space Telescope.

Simon Birrer, an assistant professor in Stony Brook’s Department of Physics and Astronomy, called the study “a milestone” and cutting-edge in trying to determine the size of the universe.

The team consists of about 30 scientists from around the globe, with the majority in the United States. They include the lead author, Patrick Kelly from the University of Minnesota.

Their focus was on a supernova — or a star that suddenly dissolved through a catastrophic explosion during which it increased its brightness tremendously. This one was, as Birrer put it in a bit of Star Wars lexicon, spotted in 2014 “in a galaxy far, far away.”

Researchers saw the supernova, called Refsdal, through NASA’s Hubble Space Telescope.

The scientists predicted where they would see yet another image of the very same light flare of the supernova exploding in 2015, which would give them an idea of how far away the supernova is — and by extension how large the universe might be.

They were correct. The supernova Refsdal explosion was indeed visible again that year at the location they expected, Birrer said.

It wasn’t easy to find the supernovae, yet alone one that appears multiple times at different locations, due to a phenomenon called gravitational lensing, he said. Plus, supernova explosions are relatively rare — perhaps one every 40 years in a galaxy.

“The measurement of the expansion rate of the universe is a roller coaster,” Birrer said. But this project was an important advancement.

“The prediction and subsequent observation of the fifth image of Supernova Refsdal was a great success,” said Anja von der Linden, an associate professor in Stony Brook’s Department of Physics and Astronomy who also took part in the study.

Von der Linden was part of the team that originally discovered Supernova Refsdal and prepared the follow-up Hubble observations.

Birrer was focused on the analysis of the measurement study, including the examination of the images of the supernova captured by the Hubble.

Soon, the researchers will be adding to their work a next-generation telescope in Chile, South America, called the Vera C. Rubin Observatory, which is especially geared to spot supernovas over a large area of the sky. Using it, they hope to locate about 50 supernovae a year.

Birrer said they got “extremely lucky” in spotting supernova Refsdal with the Hubble telescope because it has a far smaller field of view and the timing had to be just right. The addition of the telescope in Chile should allow scientists to find supernovas at a rate 100 times faster, he said.

Sherry Suyu, an associate professor at the Technical Institute in Munich, Germany, who was not involved in the study, said spotting supernovas the way the researchers did has “been very rare until now,” but with the addition of the telescope in Chile they “are expected to have hundreds of such events. We are entering an exciting era with lensed supernovae!”

Wendy Freedman, a professor in the University of Chicago’s Department of Astronomy and Astrophysics, who also was not involved in the study called its findings “an interesting and important contribution to” figuring out the size and history of the universe, though some issues remain to be resolved before scientists can get a final, more accurate figure.

Grasping the size of the universe is a somewhat mind-boggling exercise. The solar system with the eight planets including Earth that are revolving around the Sun is part of one galaxy — the Milky Way. And the Milky Way Galaxy has some 100 billion stars — the Sun is just one of them, Birrer said.

In the universe, there are tens of billions of galaxies, all with about as many stars as the Milky Way Galaxy, he said.

“It’s hard to grasp the dimension, even after studying the universe for more than a decade myself,” Birrer said, adding, “I guess we have to accept that we are just little fish in a big ocean.”

He added that it has been hard for humans to learn much about the universe, because it is so massive and inaccessible to travel to.

What scientists have learned mostly “comes from just staring at it and see what the universe reveals to us,” he said. “Our detective work is probably very similar to that of archaeologists. Astrophysicists are able to collect tiny fragments of the past and have to reconstruct a rich and dynamic history of the universe that still holds back many mysteries."

As recently as 500 years ago, scientists and everyone else still believed the Earth was the center of the universe and our solar system, with the other planets and Sun revolving around it. It wasn’t until Nicolaus Copernicus’s studies in the 1500s that we understood the Earth and other planets revolve around the Sun.

Scientists estimate the age of the universe at between 12.6 billion and 13.6 billion years. The new research project should also help calculate the number more precisely, Birrer said.