Gravitational waves from cosmic superstrings and gauge strings

• Published in: The journal of high energy physics Vol. 2024; no. 7; pp. 204 - 27
• Main Authors: Marfatia, Danny, Zhou, Ye-Ling
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 23.07.2024; Springer Nature B.V; SpringerOpen
• Subjects: Classical and Quantum Gravitation; Data analysis; Early Universe Particle Physics; Elementary Particles; Gravitational waves; Interferometers; Laser arrays; Networks; Phase Transitions in the Early Universe; Physics; Physics and Astronomy; Pulsars; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; String Theory and Cosmic Strings; String Theory and Cosmic Strings; Early Universe Particle Physics; Phase Transitions in the Early Universe
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP07(2024)204

A bstract We perform a phenomenological comparison of the gravitational wave (GW) spectrum expected from cosmic gauge string networks and superstring networks comprised of multiple string types. We show how violations of scaling behavior and the evolution of the number of relativistic degrees of freedom in the early Universe affect the GW spectrum. We derive simple analytical expressions for the GW spectrum from superstrings and gauge strings that are valid for all frequencies relevant to pulsar timing arrays (PTAs) and laser interferometers. We analyze the latest data from PTAs and show that superstring networks are consistent with 32 nHz data from NANOGrav, but are excluded by 3.2 nHz data at 3 σ unless the string coupling g s < 0 . 2 or the strings evolve in only about 10% of the volume of the higher-dimensional space. We also point out that while gauge string networks are excluded by NANOGrav-15 data at 3 σ , they are completely compatible with EPTA and PPTA data. Finally, we study correlations between GW signals at PTAs and laser interferometers.