An incredibly detailed map of the universe created with new algorithms and supercomputers

With new algorithms and supercomputers, an incredibly detailed radio map of the universe has been created. Now astronomers can examine radio data from galaxies much more accurately. This was published in Nature Astronomy by Leiden PhD student Frits Sweijen and colleagues.

“This single map has almost as many pixels as previous maps of the entire sky,” says Frits Sweijen, a doctoral student at Leiden Observatory. The researchers solved the blurring effect of UV rays in our atmosphere: with special software, they succeeded in correcting this interference. Supercomputers in Leiden and Amsterdam have used their enormous computing power to ensure that this also happens quite quickly.

Five by five full moons

For the foreseeable future, the new method could therefore highlight the entire northern sky. Now the researchers are only showing a small part of it, says Sweijen: “Suppose you see a square of five by five full moons in the sky. From this cube of space, we made a map of nearly 7 billion pixels, on which nearly 2,500 galaxies are clearly visible.

Sharper map of the four galaxies

The four galaxies on the left of the image are much sharper in the new map (right). Credit: University of Leiden

Mobile phone on Mars

Sweijen: “The map of space was made on the basis of radio waves that we captured from space with the international LOFAR telescope. It is a huge radio telescope with tens of thousands of antennas spread over a European area with a diameter of 2000 kilometers. These antennas listen to cosmic radio rays.

He continues: “Due to its enormous surface area and numerous antennae, LOFAR can ‘see’ radiation in exquisite detail, with a sensitivity that would even allow you to detect a cell phone on " data-gt-translate-attributes="[{" attribute="">March.” Data from the telescope can be seen by humans after being translated by a computer into a radiation map, a kind of photograph.

The waves scramble the signal

One problem with taking sharp pictures of the universe with LOFAR is UV radiation from the sun. It clouds our atmosphere with charged particles, ions. This ionosphere disrupts radio waves from space before the telescope picks them up. Sweijen: “It gives the impression that LOFAR is observing the sky from the seabed, where the waves are blurring the signal. Recently developed software from the Netherlands Institute for Radio Astronomy ASTRON corrected the measured radiation over the entire area. This allowed us to focus and map the entire LOFAR field of view. »

“We can now study the evolution of black holes and the galaxies in which they are found in greater detail than before.”

The software works with algorithms that require a lot of computer power. It was available. In Leiden, the newly built Academic Leiden Interdisciplinary Cluster Environment (ALICE) provided its computing power. In Amsterdam, the TIC SURF cooperation provided early access to its new Spider platform, which was specially set up for data-intensive projects such as this research.

Next shot: all the northern skies

The LOFAR field of view data correction was done in 25 sections, each a full moon size. It took seven days per area. On a single computer, it would have taken 7 times 25, or 175 days, to create the entire map. Thanks to SURF and Leiden’s large-scale infrastructure with parallel computing power, it only took seven days. This means there’s now a fast way to map the entire northern sky in comparable detail, which Sweijen says could begin within the next few years.

“We can now study the evolution of black holes and the galaxies in which they are found in greater detail than before,” he says. “Galaxies of the earlier universe, for example, which because of their distance or young age were previously too small to be seen in detail, can now be seen distinctly in the thousands.”

Reference: “Deep subarcsecond widefield imaging of the Lockman Hole field at 144 MHz” by F. Sweijen, RJ van Weeren, HJA Röttgering, LK Morabito, N. Jackson, AR Offringa, S. van der Tol, B. Veenboer, JBR Oonk, PN Best, M. Bondi, TW Shimwell, C. Tasse and AP Thomson, January 27, 2022, natural astronomy.
DOI: 10.1038/s41550-021-01573-z

Sharon D. Cole