For the first time, the signals from antenna stations of the giant radio telescope LOFAR in the Netherlands, France, Germany, and the United Kingdom have been simultaneously combined together in the LOFAR BlueGene/P supercomputer. This achievement makes the International LOFAR Telescope (ILT), an array with both excellent sensitivity, thanks to the 40 Dutch stations at the heart of the array, and excellent resolving power, thanks to its European dimensions out to 1000 km.
Published by the editorial team, 1 February 2011
LOFAR, the Low Frequency Array, was built by ASTRON in the Netherlands. It is currently being extended to European dimensions with partners in France, Germany, Sweden, and the United Kingdom (the Swedish station awaits completion later this year). Combining the Dutch and international LOFAR signals together is an important milestone that truly unites the various stations into a new and powerful facility – the ILT.
The new capabilities now realized, are demonstrated in an amazing sequence of low-frequency images of the bright radio quasar 3C196, located in a galaxy so distant that light takes 6.9 billion years to reach the Earth. This sequence shows the huge field of view that can be uniquely captured by LOFAR and covers an area of the sky equivalent to a staggering 1000 full moons, revealing a stunning variety of objects, surrounding 3C196. Some individual celestial objects may appear rather compact when viewed with the LOFAR core in the Netherlands alone. Now, with the combined multi-national resolving power of the ILT, the structure of such distant objects can be revealed with a resolution as fine as 0.2 arcseconds, close to 1/10000 of the diameter of the full moon.
ILT Director Dr. René Vermeulen of ASTRON is delighted with the news: “Years of design and development work have led to this great achievement. We now have fantastic evidence of the full potential of this revolutionary new telescope, which is drawing great interest from the astronomical community all across Europe, and beyond. Their research interests start in the upper reaches of Earth’s atmosphere, and go right out to the furthest and youngest parts of the Universe. Our first multi-national result will cement an already close international collaboration of all partners in the ILT”.
This image made with the Dutch and the international baselines offers an increase of 30 fold in resolution. The quasar 3C196 is seen to consist of two slightly extended components with the smallest detail in the image being 7 thousand light years.
Image credits of the above images: multi-national LOFAR commissioning teams led by Olaf Wucknitz (Argelander Institut für Astronomie, University of Bonn, Germany) and Reinout van Weeren (Leiden Observatory, University of Leiden).
The International LOFAR telescope is a Pan-European collaborative project led by ASTRON Netherlands Institute for Radio Astronomy. Combining thousands of simple dipole receivers with powerful digital signal processing and high-performance computing, LOFAR can rapidly survey wide areas of the sky, looking in multiple directions simultaneously and relatively unexplored low frequencies, opening open up a new window for astronomers.
LOFAR will focus on six areas of research:
1. The Epoch of Reionisation – understanding how the first stars and black holes made the universe hot.
2. Extragalactic surveys – what is the history of star formation and black hole growth over cosmological time?
3. Transients and Pulsars – probing the extreme astrophysical environments that lead to transient bright bursts in the radio sky.
4. Cosmic rays – what is the origin of the most energetic particles in the universe?
5. Solar and space environment – mapping the structure of the solar wind, how it relates to solar bursts, and how it interacts with the Earth.
6. Cosmic Magnetism – what is the origin of the large-scale magnetic fields that pervade the universe?
The quasar galaxy 3C 196
3C 196 is a quasar (compact radio source) in a galaxy so far away that light from it has travelled for almost half the age of the universe to reach us (at a redshift of z=0.871). The word “quasar” means “quasi-stellar object”. Quasars look like single stars in visible light because the light coming from close to the central black hole is so bright that it outshines all the stars in the galaxy in which it is embedded. The quasar 3C 196 was picked for the first light image of the LOFAR Telescope to show the massive increase in image sharpness (resolution) when the international stations are added to LOFAR.