Krawczynski wins NASA grant to study gamma rays at the center of the galaxy

A new camera making use of quantum technologies could reveal the origin of mysterious radiation.

Henric Krawczynski, chair and professor of physics, has received a grant from the National Aeronautics and Space Administration (NASA) worth nearly $600,000 to develop a camera that can detect gamma rays streaming from the center of the galaxy. When attached to a telescope, the camera could achieve unprecedented levels of precision. “The current gamma-ray telescopes offer a wide-field view, but modest energy resolutions,” Krawczynski said. “Our detectors will have a smaller field of view but will achieve 15 times better energy resolutions than the best current telescopes.”  

The camera will be optimized for the detection of 511 keV rays, gamma rays created when electrons and positrons — a particle and its antiparticle — destroy each other in collisions. These rays stream from the center of the Milky Way, but their source is a mystery. One intriguing possibility is that the rays could come from the annihilation of dark matter, the hypothetical and so-far undetected substance that may account for 85% of the matter in the universe. Alternatively, the gamma rays could be created by the positrons emitted near massive stars or their remnants.

The novel camera is based on detectors originally developed at the National Institute of Standards and Technology (NIST). Krawczynski and the NIST team plan to modify these detectors to track low-energy X-rays as well as more energetic gamma rays. The new camera will be operated at extremely low temperatures — less than a hundredth of a degree Celsius above absolute zero — and use superconducting quantum interference devices (SQUIDs) to amplify the signals. “When gamma rays hit the sensors, they get hotter, and we can measure the temperature increase with incredible precision,” Krawczynski said.

Krawczynski plans to eventually put the new camera into the focal plane of a 12- to 25-meter telescope, which would then fly on a stratospheric balloon or satellite. The mission would be particularly well suited to detect and characterize bright point sources of the 511 keV gamma rays. “If there are a few sources that are really bright, we’ll be able to see them very well,” Krawczynski said. Bright sources would suggest the rays are created close to individual celestial objects, not by rather uniformly distributed dark matter.

Krawczynski and Johanna Nagy, assistant professor of physics, received a NASA grant in 2021 for earlier stages of the project. They will use the latest round of funding to fine-tune the detector arrays and launch the prototype camera into space this summer with a stratospheric balloon. If the camera works as expected, they can move forward with plans to build a larger camera.  

The development of the full-fledged mission is a long-term project. Krawczynski estimates that it may take five to 10 years before the telescope first collects data. “A telescope with the necessary capabilities and specifications does not currently exist,” he said. “We’re on Zoom calls with groups around the world to see how we can combine technologies developed by different groups to move this project forward as quickly and efficiently as possible.”