Native American Heritage Month continues through November
November 12, 2019
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University of Cincinnati physicist Matthew Bayliss used a massive cluster of galaxies like a natural cosmic telescope to get our best glimpse yet of short-lived stars.
The research provides a new way to study distant, supermassive stars that burn hot and bright but die in a blink compared to our own sun.
“These high-mass stars don’t live very long. They go off like fireworks for just tens of millions of years. Finding them is a lot of work,” he said.
The study was published in the journal Nature Astronomy.
Bayliss, an assistant professor in UC’s McMicken College of Arts and Sciences, collaborated with an international team of researchers in his former position at the Massachusetts Institute of Technology. The team used the famous Hubble space telescope for optical images along with the Spitzer space telescope, which provides infrared imaging. But arguably the most important tool was the Chandra X-ray Observatory, which captures X-rays from black holes and distant stars.
Unlike light from distant stars, X-rays don’t penetrate Earth’s atmosphere. So NASA in 1999 launched Chandra high above the Earth. How high? The International Space Station, which you can see at night with the naked eye, circles about 240 miles above the Earth. Chandra flies in an elliptical orbit as far as 86,500 miles away from Earth.
It's as if the universe placed a magnifying lens in space.
Matthew Bayliss, UC physicist explaining 'gravitational lensing'
To record X-rays from such distant sources, Bayliss used a phenomenon called gravitational lensing, which magnifies the star’s observable electromagnetic radiation. Albert Einstein predicted the effects of gravitational lensing in his theory of general relativity and even described how gravity could warp light and other energy.
“It’s as if the universe placed a magnifying lens in space,” Bayliss said. “We can take our best telescopes and point them at these natural gravitational lenses, which amplify the power of our telescopes. You can see more distant things and more faint things than you otherwise would.”
The study marked the first use of gravitational lensing to observe distant stars through X-ray detection. But Bayliss said the tool could reveal the secrets of other supermassive stars, which are difficult to study because of how short-lived and distant they are.
“If you think of 50,000 people of all ages in a stadium, the odds of finding a 4-month-old baby are pretty small because babies aren’t 4-months-old for very long,” Bayliss said. “If you were studying middle-aged people, you’d get lots of data. But you wouldn’t have many babies to work with.
“The fraction of a lifetime that a human is a toddler is tiny in the same way that the fraction of the history of a galaxy that contains supermassive stars is tiny,” Bayliss said.
University of Michigan associate professor Keren Sharon, a co-author of the study, said gravitational lensing allows researchers to study galaxies that would be too faint to observe otherwise.
“We've been taking advantage of ‘cosmic telescopes’ to study faint galaxies in long wavelengths for a couple of decades now,” she said.
“Being able to observe them in the X-ray regime opens a window for new discoveries and enables detailed studies of intrinsically faint X-ray sources that would otherwise have to wait for the next generation of telescopes.”
Massive dying stars eventually collapse, ejecting their matter in a supernova explosion before becoming neutron stars or black holes. Despite vast improvements in astronomical observation, comparatively little is known about the origins of these massive stars and how they might influence each other, Bayliss said.
“We’re hoping to understand how young stars form in the distant universe,” he said.
Featured image at top: UC physicist Matthew Bayliss explains gravitational lensing with an equation. Photo illustration/Lisa Ventre and Margaret Weiner/UC Creative Services
International Business Times: Astronomers Use Galaxy Cluster to See 9 Billion Years into the Past
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