EPTA announces evidence for nanohertz gravitational waves

Clock-like precision of pulsars opens a new ultra low-frequency gravitational wave window

EPTA, the European Pulsar Timing Array, has published today the results of more than 25 years of research, showing a significant breakthrough in detecting ultra-low-frequency gravitational waves. The international collaboration of astronomers from Europe, along with the Indian PTA scientists from India and Japan, has analyzed data collected six of the world's most sensitive radio telescopes and found evidence of gravitational waves, which are believed to originate from pairs of supermassive black holes in merging galaxies. SISSA played a notable role in the effort, contributing especially on the modeling and interpretation of the data through the work of Enrico Barausse’s research group. 

The results of the collaboration, published today in a special issue of “Astronomy and Astrophysics”, are based in the detection of small changes in the signals coming from pulsars, extinguished stars that emit light and radiation pulses in a regular, clock-like fashion. “One of our contributions was to the interpretation of these minute variations: by using models developed in our and other research groups, we show that the results are consistent with the merging of supermassive black holes” explains Marco Crisostomi, Post-Doc in Barausse’s research group and co-author of the Implications for massive black holes, dark matter and the early Universe paper in the special issue.  

Indeed, ultra-low-frequency or nano-hertz gravitational waves hold the potential to open a new window into unresolved mysteries of the universe, including the search for dark matter. “We can indirectly probe the nature of dark matter by observing these signals” explains Clemente Smarra, PhD student at SISSA and first author on the paper Challenging the ultralight dark matter paradigm. “The preliminary results here show that we can exclude the presence of so-called “ultra-light” dark matter in most of the parameter space that we probe, but there may something intriguing at play in one of our data segments.”. 
To further solidify this new breakthrough, the EPTA collaboration is working towards expanding the current dataset, which will involve utilizing an array of over 100 pulsars observed by thirteen radio telescopes and accumulating thousands of observations for each pulsar. By doing so, they aim to to expand even further the gravitational wave window on the Universe. 

Read the official EPTA statement:

All papers and the release dataset are available here:

Image Credit: David Champion / MPIfR