The discovery of the gravitational wave background in 2016 marked a significant milestone in our understanding of the Universe. This groundbreaking discovery was further validated by the release of a second data set from the European Pulsar Timing Array, along with the addition of data from the Indian Pulsar Timing Array. These complementary studies have provided more evidence for the existence of the gravitational wave background, shedding light on the cosmic phenomena that shape our universe.

Gravitational waves are ripples in spacetime that are generated by violent processes such as merging black holes and colliding neutron stars. Predicted by Einstein in 1916 as part of his General Theory of Relativity, these waves have the ability to travel through space, largely unimpeded by any obstacles in their path. The first detection of gravitational waves in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) confirmed their existence, originating from a gravitational merger between two black holes located 1.3 billion light years away.

The recent confirmation of the gravitational wave background by the European and Indian Pulsar Timing Arrays indicates that we are detecting a combined signal from the mergers of supermassive black holes. This random distribution of gravity waves that permeates the Universe offers a new avenue for studying the cosmos, akin to the Cosmic Background Radiation. The collaborative efforts of various observatories and research institutions have enabled us to delve deeper into the mysteries of the Universe.

Utilizing pulsar timing arrays as galaxy-sized detectors, researchers have been able to monitor and analyze the pulse arrival times of galactic pulsars on Earth. By detecting subtle patterns in these signals, they can uncover the presence of the gravitational wave background. The latest study led by J. Antoniadis from the Institute of Astrophysics in Greece delves into the implications of the low-frequency signals observed in the recent data releases from various pulsar timing array systems.

The accumulation of data from multiple sources has provided undeniable evidence for the existence of the gravitational wave background. With ongoing Pulsar Timing Array projects, the signals of the low-frequency gravity waves will become more distinct, offering a wealth of opportunities to explore the Universe in this novel way. The focus now shifts towards interpreting these signals to unlock the secrets of the cosmos.

Source : The second data release from the European Pulsar Timing Array: IV. Implications for massive black holes, dark matter and the early Universe