UK’s bit of LoFar opened for business

The UK branch of the Low Frequency Array has been officially opened by Pulsar discoverer Dame Jocelyn Bell-Burnell.

The radio telescope, which has stations dotted around Europe, will combine signals in a process called interferometry to create a single large telescope operating in the 1-10m wavelength. This aperture synthesis will allow higher resolution images than an individual station would be able to achieve. This is necessary as resolution depends on wavelength and the diameter of a telescope. At metre wavelengths, the size of a telescope required is enormous. LoFAr’s arrangement is such that the combined signal will be equivalent to a telescope the size of the separation of the individual stations, while the sensitivity will be equivalent to the combined sensitivity of the observatories.

Aperture synthesis is routinely used in radio astronomy to counter the poor resolution of radio waves, but rarely on this scale. It has also been used in shorter wavelengths, but this is more difficult as the higher frequencies of light make adding the signals more complex. Telescopes like Keck and Subaru are designed to use large single observatories in pairs to achieve larger synthetic observatories in infrared and even optical light.

Each new wavelength regime observed opens a new chapter in astronomy. Higher energy events are seen at low wavelengths, with things as hot as stars and aurorae generally in ultraviolet and mostly optical regimes. Newly forming protostars, existing planets and asteroids are seen to glow brightest in the infrared and dust as well as the background hiss of the afterglow of the formation of the optically thin universe, the CMB, are seen in the microwave. Radio wavelengths most often show the emissions from charged particles deflected by magnetic and other fields. As such, the new telescope can be used to observe magnetic fields on the cosmic scale, the interaction of the solar plasma with objects in the solar system, cosmic rays hitting our atmosphere and processes involved in star formation and the growth of black holes, all of which involve or are revealed by the deflection of charged particles to a greater or lesser extent.


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