NASA’s Hubble Space Telescope just finished taking its widest-ever near-infrared image of the universe, an area almost seven times the size of our moon. That such an image is possible is due to an innovative new technique, called Drift And SHift (DASH), which increased the imaging speed of Hubble by a factor of eight. This shallow but deep image, published recently in The Astrophysical Journal, will help astronomers study some of the brightest but rarest events of the Universe, such as monster galaxies, active galactic nuclei and galaxies close to mergers.
The research, which was led by Lamiya Mowla, postdoctoral researcher at the University of Toronto, is focused on the infrared part of light’s spectrum. That’s because “different wavelength ranges reveal different things about the universe,” according to UMass Amherst’s Sam Cutler, a graduate student in astronomy and the paper’s second author. “The further away something in the universe is, the longer the light from that object takes to get to us. When we see something millions or billions of lightyears away, we’re actually seeing something as it was millions or billions of years ago. As that light travels through space, its wavelength gets stretched, which means it becomes redder. So, if you want to see the earliest events in the universe, which are billions of lightyears away, you have to be able to see infrared light.”
The 3D-DASH imaging was stitched together from 157 orbits, and 1,256 pointings, of Hubble spanning seven years, from 2014 to 2021. This panorama will enable astronomers to identify and study distant, rare galaxies such as those massive, highly star-forming ones, close-pairs and quasars.
The result is simply stunning: a mosaic of galaxies and galaxy pairs, many of which are billions of years old.
“Since its launch over 30 years ago,” says Mowla, “the Hubble Space Telescope led a renaissance in the studies of how the shapes and sizes of galaxies have changed in the last 10 billion years of the universe through its deep imaging. The 3D-DASH program has now extended Hubble’s legacy in wide-area imaging. 3D-DASH will enable a census of rare objects and find targets for follow-up with the upcoming James Webb Space Telescope.”
Hubble has far surpassed its anticipated mission lifetime, but its days are numbered. The next generation of space telescopes, such as Euclid, which will launch around 2024, and the Nancy Grace Roman Space Telescope, which will launch after 2025, will be capable of doing deep, wide-area, high-resolution imaging of the sky much more efficiently. Until then, 3D-DASH will remain the state-of-the-art wide field near-infrared image of the universe.
“This is an extremely creative use of Hubble,” notes Kate Whitaker, professor of astronomy at UMass and one of the paper’s co-authors. “It hasn’t been done before; it pushes the limits of what Hubble can do and it is critical to understanding the early formation of our universe.”