Check out the MWA Sky
Interested in the radio sky at low frequencies? Then,check out the Murchison Wide-field Array (MWA). A few years ago, we worked on a video about the MWA, located in the outback of Western Australia. The video was created for the MIT Haystack Observatory, which was involved with the project. We interviewed Colin Lonsdale, who is director of Haystack, and created a short explainer about the observatory. It was a fun project and I’ve kept tabs on the MWA’s progress ever since.
A Sky in Radio Technicolor
Recently the folks who run MWA released an image from a sky survey they’ve made called GLEAM (which stands for GaLactic and Extragalactic All-sky MWA). The combined MWA receivers scanned the sky at frequencies between 70 and 230 MHz. These are very low-frequency waves that can be easily disrupted by TV and radio signals (among others). So, MWA is located literally in the middle of nowhere with a fine view of the sky. In the image they released, red denotes the lowest frequencies received, green is the middle of the range, and blue indicates the highest ones. This is what gives the image its ‘technicolor’ look. That works for our eyes, which can only see three primary colors. MWA actually detects more than 20 colors.
What Does MWA “See”?
Among the objects that MWA can detect in its frequency bands are ancient supernova explosions and emissions from distant black holes. They are just a few of the types of celestial sites that lie in the 24,402 square degrees of sky that the MWA covered in the survey. In that region, there are more than 307,000 radio sources. If you’re interested in the full paper from the survey team, it’s available here and gives all the details about the survey and data reduction.
MWA’s survey is part of the path to the final deployment of the low-frequency part of the Square Kilometre Array. Once built out, SKA will build on MWA’s work, further defining and refining the radio sky at radio frequencies well below what other arrays are detecting. In particular, the work will help astronomers dig further into the distant, early universe. That’s still a largely unstudied realm of the cosmos, and astronomers are anxious to learn more about what happened way back then.