Cosmic Whispers: Scientists Detect Universe-Wide Gravitational Wave Background

Scientists have made a groundbreaking discovery in the field of astrophysics - the detection of low-frequency gravitational waves that permeate the entire universe. This finding, announced by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), marks a significant milestone in our understanding of the cosmos (Arzoumanian et al., 2023).

Gravitational waves are ripples in the fabric of spacetime, first predicted by Albert Einstein in his theory of general relativity (Einstein, 1916). They are created when massive objects accelerate through space, causing distortions in the universe’s structure. While high-frequency gravitational waves from violent cosmic events like black hole mergers have been detected since 2015 (Abbott et al., 2016), this new discovery reveals a constant background “hum” of low-frequency waves.

These newly detected waves are thought to originate from pairs of supermassive black holes orbiting each other in the early universe (Sesana et al., 2008). Unlike the short “chirps” from black hole mergers detected by LIGO (Laser Interferometer Gravitational-Wave Observatory), these waves have much longer wavelengths and periods, taking years to complete a single oscillation.

The discovery was made by analyzing 15 years of data from pulsars - rapidly rotating neutron stars that emit regular pulses of radiation. As gravitational waves pass through space, they cause minute changes in the timing of these pulses, which scientists can detect and measure (Foster and Backer, 1990).

This breakthrough opens up a new way to study the universe, particularly the behavior of supermassive black holes and galaxy formation. It’s akin to scientists gaining a new sense to perceive the cosmos, allowing them to “hear” the gravitational echoes of events from billions of years ago (Burke-Spolaor et al., 2019).

The detection of this gravitational wave background is a testament to the power of long-term, collaborative scientific efforts. It not only confirms Einstein’s predictions but also provides a new tool for exploring the mysteries of our universe (Hobbs et al., 2010).

For more details, read the article Scientists use Exotic Stars to Tune into Hum from Cosmic Symphony

References:

Abbott, B.P. et al. (2016). Observation of Gravitational Waves from a Binary Black Hole Merger. Physical Review Letters, 116(6).

Arzoumanian, Z. et al. (2023). The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background. The Astrophysical Journal Letters, 944(2).

Burke-Spolaor, S. et al. (2019). The Astrophysics of Nanohertz Gravitational Waves. The Astronomy and Astrophysics Review, 27(1).

Einstein, A. (1916). Die Grundlage der allgemeinen Relativitätstheorie. Annalen der Physik, 354(7).

Foster, R.S. and Backer, D.C. (1990). Constructing a pulsar timing array. The Astrophysical Journal, 361.

Hobbs, G. et al. (2010). The International Pulsar Timing Array project: using pulsars as a gravitational wave detector. Classical and Quantum Gravity, 27(8).

Sesana, A., Vecchio, A., and Colacino, C.N. (2008). The stochastic gravitational-wave background from massive black hole binary systems: implications for observations with Pulsar Timing Arrays. Monthly Notices of the Royal Astronomical Society, 390(1).