Radio astronomers avoid Earth’s disturbing atmosphere with new calibration technique

An international research team led by astronomers from Leiden University (Netherlands) has created the first clear radio map of the universe at low frequencies. Thanks to a new calibration technique, they avoided interference with Earth’s ionosphere. They used a new method to study plasma from the eruption of an ancient black hole.

Astronomy and Space Astronomy Editor’s Note Radio astronomers avoid Earth’s disturbing atmosphere with new calibration technique From the Dutch School of Astronomy Radio astronomers avoid Earth’s disturbing atmosphere with new calibration technique The old against the new. On the left is an image of a portion of the sky observed using the best calibration technique to date. The right side shows part of the same sky with new technology. More detail appears, and previously large, blurry spots now appear as individual dots.

An international research team led by astronomers from Leiden University in the Netherlands has created the first clear radio map of the universe at low frequencies. Thanks to new calibration techniques, they avoided interference with the Earth’s ionosphere. They used a new method to study plasma from ancient black hole eruptions. This technique could help find exoplanets orbiting small stars. The researchers report on their technique in the journal Nature Astronomy. This technology allowed astronomers for the first time to take clear radio images of the universe at frequencies from 16 to 30 MHz. This was previously thought impossible, as the ionosphere, located about 80 kilometers above Earth, blocks observations at these frequencies. The researchers used the LOFAR telescope in Drenthe, Netherlands, which is currently one of the best low-frequency radio telescopes in the world. To test their technique, they looked at a set of galaxy clusters that had previously only been studied in detail at higher frequencies. Thanks to the new images, we can see that the radio emission from these clusters is not evenly distributed throughout the cluster, but rather in a point-like pattern. “It’s like when you put on glasses for the first time and you can’t see anymore,” said study leader Christian Groeneveld from Leiden University. The motivation for the study was that many improvements in calibration have already been achieved in recent years at high frequencies around 150 MHz. “He wanted to extend this technology to lower frequencies, below 30 MHz,” says Leiden University’s Rheinout van Wielen, who originated the idea. “And we succeeded.” Researchers are now processing the data further to map the entire northern sky at lower frequencies. Researchers say the new calibration technique allows them to study previously hidden phenomena. This makes it possible to discover exoplanets orbiting small stars. “Of course, it’s possible that something unexpected will be discovered at some point,” Groenefeld concluded.

source: https://phys.org/journals/nature-astronomy/