& lead Physics 17, s62
Spatial ripples known as cosmic strings, which may have formed in the early Universe, may be a dominant source of gravitational waves at extremely high frequencies, according to new calculations.
University C. Ringeval/Louvain
Existing and planned gravitational wave detectors, from pulsar timing arrays to laser interferometers, probe signal frequencies up to several kilohertz. But the higher frequencies provide a detection window clear of astrophysical signals (such as those from black hole binaries) and dominated by signals coming from the early processes of the Universe (inflation, initial phase transitions, and more ). Now Géraldine Servant of the University of Hamburg, Germany, and Electron Synchrotron DESY and Peera Simakachorn of the University of Valencia, Spain, calculate the spectrum of a possible source of primordial signals – cosmic strings [1]. The results suggest that cosmic strings may be the dominant source of ultra-high frequency signals.
Cosmic strings are nearly one-dimensional, topological defects in spacetime, which, like cracks in ice, can form during a symmetry-breaking phase transition. Such strings can form loops that break up releasing gravitational waves. Servant says the search for these waves is well motivated, since cosmic strings appear in most theories that go beyond the standard model of particle physics. The pair consider two scenarios where strings result from “local” and “global” symmetry breaking and calculate their respective emissions. The researchers conclude that local strings may generate most of the high-frequency emission allowed by existing observational constraints, dampening the signal from “global” strings associated with models involving hypothetical “heavy stock” particles.
If detectors ever achieve the sensitivity needed to distinguish these signals, the slopes and curves in the signal spectrum would carry information about the fields that produced the strings, potentially holding the key to developing grand unified theories. However, new calculations show that none of the previously theorized concepts of the detector [2] offers serious breakthrough potential, says Simakachorn. Servant adds, “It’s clear that we would need some sort of revolution in detection techniques, but the scientific case for primordial signals is very strong.”
Matteo Rini
Matteo Rini is the editor of Journal of Physics.
References
- G. Servant and P. Simakachorn, Ultrahigh frequency primordial gravitational waves beyond kHz: The case of cosmic strings, Phys. Rev. D 109103538 (2024).
- N. Aggarwal et al.Challenges and opportunities of gravitational wave research at MHz to GHz frequencies, Living Rev. Relative. 244 (2021).
Subject areas
#Cosmic #strings #embedded #highfrequency #gravitational #waves
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