Most microscopes let scientists peer straight into a single cell. The Dragonfly Spectral Line Mapper (DSLM) applies a similar idea on a much larger scale—a galactic scale. Instead of using one large lens to gather light, the instrument relies on dozens of small camera lenses to capture details too faint for ordinary telescopes. Each lens is paired with a special filter that can be tilted to select different colors of light.
In a recent article published in Publications of the Astronomical Society of the Pacific, Pieter van Dokkum, Yale professor of astronomy and physics, and his colleagues used the DSLM to observe the universe. “The idea was about trying to detect gas and dark matter in the universe, because we think that all galaxies are connected to each other in the cosmic web, which is made up of strands of dark matter and gas,” van Dokkum said.
The DSLM was pointed at three galaxies: NGC 6946, NGC 891, and NGC 7479, which were chosen based on their relative location and shape. The research team collected thousands of frames that were later stacked on top of one another to detect surface brightness limits, which are the dimmest light levels measured around galaxies.
Their results display that the galaxies extend beyond the regions where their stars appear to disappear. The luminescent rings of mapped light that surround the galaxies are outer layers of glowing hydrogen gas, giving a clue into how galaxies form and develop.
Discoveries like this help scientists understand how galaxies evolve, and this is just the beginning. “We are currently building a telescope with 1,140 lenses in Chile that should be done by the end of next year,” van Dokkum said. This project will reveal the hidden mysteries of other galaxies on a much more detailed scale than before.