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

An international team of researchers, led by Leiden astronomers, has created sharp radio maps of the universe at low frequencies for the first time. Thanks to a new calibration technique, they circumvented the disturbances of the Earth’s ionosphere. With the new method they studied plasmas from old black hole outbursts. The technique may also be suitable for finding exoplanets orbiting small stars (Nature Astronomy6 May).

For the first time, the technology allows astronomers to make sharp radio images of the universe at frequencies between 16 and 30 MHz. Until now, it was always thought that this was impossible, because the ionosphere about eighty kilometers above the Earth interferes with observations at these frequencies.

The researchers used the LOFAR telescope in Drenthe. This is currently one of the best radio telescopes in the world for low frequencies. To test their technique, they studied a number of galaxy clusters that until now could only be viewed in detail at higher frequencies.

The new images show that the radio emission from these clusters is not evenly distributed over the entire cluster, but that there is a spot pattern.

The researchers are currently processing more data so that they can map the entire northern sky at low frequencies.

Full press release