The Low-Frequency Array (LOFAR) is a special type of radio telescope. Though radio mild has the longest wavelengths and lowest frequencies of the electromagnetic spectrum, a lot of radio astronomy has targeted on the upper frequency finish. Observatories resembling ALMA examine radio mild at frequencies of tons of of Gigahertz, and the VLA research the fifty Gigahertz vary, LOFAR captures radio indicators under 250 Megahertz, which is within the vary of the bottom radio frequencies that may be seen from Earth.
Low-frequency radio astronomy is difficult as a result of astronomical radio sources are very faint. Low-frequency mild additionally has an extended wavelength, which signifies that it’s exhausting to seize radio photographs with good decision. To beat these challenges, LOFAR makes use of an array of omnidirectional antennas. It has about 20,000 antennas clustered at 52 stations throughout Europe. Collectively they create a digital telescope greater than 1,000 kilometers throughout. With such numerous antennas, processing the info is extraordinarily complicated. Different radio telescopes additionally mix a number of indicators from an antenna array, however LOFAR operates at such low frequencies that Earth’s ionosphere can distort the indicators. It’s much like the best way seen mild might be distorted when considered by ripples of water. So highly effective new software program needed to be developed to transform the radio information into photographs of the sky.
Not too long ago, LOFAR launched the primary information on its Lengthy Baseline Array Sky Survey. They’ve solely mapped 4% of the northern sky up to now, however have already mapped 25,000 supermassive black holes. Whereas the universe is full of radio sources, most low-frequency radio mild comes from concentrated sources resembling black holes on the hearts of galaxies. LOFAR has a excessive sufficient decision that the black gap map seems like a starry night time, with every black gap as an remoted radio dot, as you possibly can see within the picture above.
It is going to take a number of extra years for the group to make a full map of the northern sky. When accomplished, the sky survey may assist us be taught not solely about black holes but additionally in regards to the large-scale construction of the cosmos.
Reference: de Gasperin, F., et al. “The LOFAR LBA Sky Survey I. survey description and preliminary data release.” arXiv preprint arXiv:2102.09238 (2021).