Gravitational Wave Signatures of Cosmic String Networks

Cosmic strings are hypothesised one-dimensional topological defects formed during symmetry-breaking phase transitions in the early Universe. As these strings evolve, they intersect and form loops which oscillate relativistically, emitting gravitational radiation across a broad frequency range. The resulting stochastic gravitational-wave background (SGWB) carries distinctive spectral features—such as power-law segments, spectral breaks and “knees”—that encode the underlying string tension, loop distribution and cosmic history. By mapping these signatures, one can probe fundamental physics scales, constrain models of the early Universe and test scenarios ranging from primordial black hole domination to non-standard pre-Big Bang Nucleosynthesis evolution. Prospective detection spans pulsar timing arrays at nanohertz frequencies, space-borne interferometers in the millihertz band and ground-based detectors at kilohertz scales, offering a comprehensive window into cosmic string dynamics and their cosmological context.

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Gravitational Wave Signatures of Cosmic String Networks publication trend

The graph below shows the total number of articles in gravitational wave signatures of cosmic string networks across all publications each year (not limited to Nature Index journals).

Technical terms

Cosmic string network: A collection of one-dimensional topological defects that evolve, intersect and form closed loops in an expanding Universe.

Stochastic gravitational-wave background (SGWB): A superposition of unresolved gravitational-wave signals from many independent and random sources, yielding a diffuse spectrum.

Loop formation and decay: The process by which long cosmic strings intersect to form closed loops, which then shrink through emission of gravitational waves and, in some models, particle radiation.

Spectral break (“knee”): A change in the power-law slope of the gravitational-wave spectrum, marking transitions between different emission or cosmological regimes.

Equation of state: The relation between pressure and energy density in the cosmological fluid, determining how the Universe’s expansion rate varies with time.

References

1. Primordial black hole archaeology with gravitational waves from cosmic strings. Journal of High Energy Physics (2023).
2. From NANOGrav to LIGO with metastable cosmic strings. Physics Letters B (2020).
3. Probing the pre-BBN universe with gravitational waves from cosmic strings. Journal of High Energy Physics (2019).
4. Cosmic archaeology with gravitational waves from cosmic strings. Physical Review D (2018).
5. Decay of Cosmic String Loops due to Particle Radiation. Physical Review Letters (2019).