Looking back billions of light-years into the universe, the time when many galaxies and stars were forming, requires some major vision enhancements. Even the lenses of our most powerful telescopes have not been enough to capture high-quality images for stars being born, but luckily the universe had the prescription astronomers needed on hand: gravitational lenses.
Thanks to this natural phenomenon of gravitational lensing and the power of the ALMA space telescope, astronomers were able to capture the most detailed images of star formation to date. The findings are published in eight separate papers in Astrophysical Journal Letters.
"In the case of this study here we were able to look inside a galaxy and see how stars are forming and how they're forming in a level of detail 10 times higher than we would otherwise be able to without this natural amplification," study author Mark Swinbank, an extra-galactic astronomer at the University of Durham, told Tech Times.
The way gravitational lensing works is similar to the way the lenses on a pair of glasses work. Because the glass is denser than the surrounding medium, air, light moves through the lens differently. The glass bends the light such that the image of the object the light was reflected from looks larger.
"In space, you don't have lenses but you have galaxies that are rather dense compared to the surrounding medium," says Swinbank. "That density acts the same way the lenses on glasses do and actually bends the light."
When astronomers look deep into the universe, they are effectively looking back in time. This is because they are seeing light that galaxies or other cosmic objects emitted millions or billions of years ago, but the light is still traveling the vast distance across the universe. The galaxies Swinbank and his colleagues studied in this latest work were seen when universe was 2.5 billion years old. For comparison, the universe is now about 13.5 billion years old.
"You're looking back to a time when massive galaxies were just in the process of forming and forming a lot of their stars," says Swinbank. "The reason we want to study these galaxies at these early times is that we want to try and understand how galaxies like the Milky Way formed."
ALMA is itself an extremely powerful imaging tool, and a relatively new one. It has only been in use for a few years, and Swinbank says that we can expect more astonishing images from the telescope in the years to come.
"It's the combination of ALMA and gravitational lensing that has allowed us to get exquisitely sharp images," he says. "This is like a pathfinder for ALMA - it's a demonstration of what ALMA is going to be able to do in the future."
The powerful Atacama Large Millimeter/submillimeter Array (ALMA) studies the universe at the long-wavelength millimeter and submillimeter range of light. Located in the Atacama desert of Chile, it's designed to spot some of the most distant, ancient galaxies ever seen and to survey young stars for planets in the process of forming.
