One Million Galaxies Never Seen Before

LOFAR sky map reveals a flurry of new discoveries

Jülich, 25 February 2022 – For seven years, an international research team has collected radio signals from space. The data have now been published as a new sky map, which provides a unique picture of the wonders of our universe. For the first time, 4.4 million galaxies were made visible in the radio wave range. One million of these galaxies were previously completely unknown. The discoveries were made using the European LOFAR telescope, the largest radio telescope ever built. The Jülich supercomputer JUWELS, currently the fastest supercomputer in Europe, helped to process the gigantic data sets with its enormous computing power.


Intergalactic particles

Der Coma-Cluster ist 300 Millionen Lichtjahre von der Erde entfernt und besteht aus mehr als 1.000 Galaxien, die hier im Radio- und Infrarot-Bereich gezeigt sind. Die Radiodaten machen die Strahlung von hochenergetischen Teilchen sichtbar, die den Raum zwischen den Galaxien durchdringen.
Annalisa Bonafede

By using the European radio telescope LOFAR, the researchers have mapped around a quarter of the northern sky in unprecedented resolution and made it accessible to the public online The vast majority of these objects are billions of light years away and are either galaxies that harbour massive black holes or are rapidly growing new stars. Rarer objects that have been discovered include colliding groups of distant galaxies and flare stars within the Milky Way.


Remains of a supernova

Überreste einer Supernova
Die Überreste einer Supernova, Cygnusbogen genannt, sind hier im Radio-, UV- und Röntgenbereich gezeigt. Sie befinden sich in der Milchstraße. Dorthin wird sich der Blick von LOFAR in Zukunft wenden. Das Radioteleskop beginnt gerade, unsere eigene Galaxie zu erforschen.
Jennifer West

“This project is so exciting to work on. Each time we create a map, our screens are filled with new discoveries and objects that have never before been seen by human eyes,“ says Timothy Shimwell from the Netherlands Institute for Radio Astronomy (ASTRON) and Leiden University.

New members in the galaxy zoo

The wealth of new information contained in the maps is evident from a host of recent scientific publications that make use of the radio images. For example, the team today published the largest ever studies of colliding galaxy clusters comprising between hundreds and thousands of galaxies – the universe’s largest structures.


Crash of the galaxies

Jeder einzelne Quadrant dieses Bildes zeigt die Kollision zweier gigantischer Galaxiencluster. Jeder der Cluster besteht aus Hunderten oder Tausenden von Galaxien. Diese energiereichen Ereignisse sind die seltensten seit dem Urknall. Sie senden riesige Schockwellen durch das Universum, deren Turbulenzen sich über Millionen von Lichtjahren erstrecken.
Andrea Botteon

Previous results include: finding curious signals from nearby stars that may be induced by orbiting exoplanets; pinpointing the slowest spinning pulsar that challenges current theories describing such objects; observing so called “jellyfish galaxies” shedding material as they travel through the surrounding medium; and discovering so many radio galaxies of all shapes, sizes, and ages that a citizen science project has been set up to help find new black holes in this zoo of objects.


Jellyfish galaxy

Die Jellyfish-Galaxie NGC 4858 im sichtbaren Licht und Radiowellenbereich: Sie verdankt ihre Bezeichnung der Tatsache, dass sie durch ein dichtes Medium fliegt, welches Material aus der Galaxie abstreift, sodass ein Schweif entsteht.
Ian Roberts

Data to fill 20,000 laptop hard drives

Whilst these discoveries are already refining our understanding of the universe, it is also clear that the research conducted to date merely scratches the surface of what is yet to come. The data that have been released only represent 27 percent of the entire survey. Nevertheless, they are based on really large data sets. To produce the map, researchers processed 3,500 hours of observations that occupy 8 petabytes of disk space – the equivalent to roughly 20,000 laptops. A large part of this, over 60 percent, comes from the LOFAR long-term archive at the Jülich Supercomputing Centre (JSC). The JSC at Forschungszentrum Jülich is one of three data centres participating in the project. It hosts about onef third of the LOFAR data archive, which totals around 55 petabytes.

Superrechner JUWELS
JUWELS-Supercomputer in der Rechnerhalle des Jülich Supercomputing Centre
Forschungszentrum Jülich / Wilhelm-Peter Schneider

“In order to make sense of this enormous amount of data generated by the LOFAR telescope, high-performance computers stationed throughout Europe are used. A major challenge is the calibration of the measured signals, for which we were able to access the Jülich supercomputer JUWELS, which has a computing capacity equivalent to 300,000 modern PCs,” says Matthias Hoeft of the Thuringian State Observatory in Tautenburg. “This is an important task. In a first step, interfering influences on the signals are determined from the measurement data using cutting-edge algorithms. These disturbances are filtered out if necessary, so that the actual brightness distribution of the sky can be reconstructed for scientific evaluations.”

Prospect of further findings

The LOFAR data are available to researchers worldwide. Many more scientific breakthroughs are expected in the future. “The link with observations from other frequency ranges can, for example, provide new insights into the properties of dark energy, which are still poorly understood. They also enable new insights into the formation of galaxies and even larger structures in the universe," says cosmologist Dominik Schwarz from Bielefeld University, who is coordinating Germany’s contribution to LOFAR.


Highly energetic universe

Hochenergetisches Universum
Timothy Shimwell

Scientists from the Ruhr University Bochum (RUB) also use the LOFAR data to study the evolution of galaxies and dwarf galaxies with extremely high star formation rates. “The completely new technology of the LOFAR radio telescope opens up many new possibilities for us to study high-energy physical processes in the world of galaxies,” says RUB researcher Ralf-Jürgen Dettmar.


Whale galaxy

Die Wal-Galaxie NGC 4631 in drei verschiedenen Wellenlängenbereichen: Die Sternentstehung in der Galaxie produziert heißes Gas, das im Röntgenbereich sichtbar ist (blau), sowie hochenergetische Teilchen, die sich im Radiobereich offenbaren (orange). In der Mitte überlagert gezeigt ist ein Bild der Galaxie im Bereich des sichtbaren Lichts.
Volker Heesen & Michael Stein

Research teams at the universities in Hamburg and Bielefeld and the Observatory in Tautenburg, meanwhile, are studying gigantic radio sources to investigate the origin of magnetic fields in the cosmos. “One result that has already been obtained by using the data is that the magnetic fields in the universe must have grown to their current strength at quite an early stage. The reason for this is that chaotic gas movements rapidly strengthen the magnetic fields in a process known as dynamo amplification,“ says Marcus Brüggen from the Hamburg Observatory.


Early quasar

Dieser unscheinbar aussehende rote Quasar ist eines der gewaltigsten Objekte im frühen Universum und entstand innerhalb von 1 Milliarde Jahre nach dem Urknall. Hier sehen wir den Quasar, wie er vor 12,9 Milliarden Jahren aussah, als sein zentrales Schwarzes Loch schnell Material ansammelte und starke Ausbrüche erzeugte, die im Radiowellenbereich leuchten. Es ist noch nicht vollständig geklärt, wie solch starke Quellen so kurz nach dem Urknall entstanden sind.
Anniek Gloudemans

Virtual telescope LOFAR

LOFAR, the Low Frequency Array, is controlled by the ASTRON institute in the Netherlands and is the forerunner of a new type of radio telescope. It consists of more than 50 stations across seven European countries that are connected to powerful supercomputers via fast fibre optic connections. The enormous computing power is needed to combine the signals from the many thousands of individual antennas. This results in a virtual antenna dish with a diameter of 1,900 kilometres, which is able to distinguish between very weak signals and signals that are very close to each other.

Die Jülicher LOFAR-Station DE605 besteht aus zwei Antennenfeldern zur Messung hoher und niedriger Frequenzen. Der Container in der Mitte enthält Elektronik zur Verarbeitung der Signale der einzelnen Antennen.
Ralf-Uwe Limbach

In Germany, six stations are operated by different scientific institutions. One of them is located southeast of the Forschungszentrum Jülich campus and is operated by the JSC together with Ruhr University Bochum. In addition, the JSC manages the data network traffic between the German LOFAR stations and the central LOFAR computer in Groningen via modern fibre-optic multiplexing connections.

Blick ins Magnetbandarchiv: Das Forschungszentrum Jülich beherbergt etwa 17 Petabyte des LOFAR-Datenarchivs, das insgesamt rund 55 Petabyte umfasst.
Ralf-Uwe Limbach

Original publication:

T. W. Shimwell, M. J. Hardcastle, C. Tasse, P. N. Best, H. J. A. Röttgering, W. L. Williams, A. Botteon, A. Drabent, A. Mechev, A. Shulevski, R. J. van Weeren et al.
The LOFAR Two-metre Sky Survey (LoTSS). V. Second data release
Astronomy & Astrophysics (published online 25 February 2022), DOI: 10.1051/0004-6361/202142484

Further information:

LOFAR surveys

Jülich Supercomputing Centre (JSC)

Press release, February 2019: New Map of the Sky Published

Video: Supercomputer JUWELS (length: 4:01 min.)


Cristina Manzano
Jülich Supercomputing Center (JSC)
Tel: +49 2461 61-1958

Dr. Arpad Miskolczi
Jülich Supercomputing Center (JSC)
Tel: +49 2461 61-1958

Prof. Dr. Dr. Thomas Lippert
Jülich Supercomputing Center (JSC)
Tel: +49 2461 61-6402

Press contact:

Tobias Schlößer
Corporate Communications
Tel:: +49 2461 61-4771

Last Modified: 04.01.2023