Preprint

PUBDB-2025-04772

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png When Geometry Radiates Review: Gravitational Waves in Theory, Cosmology, and Observation

Maleknejad, A. (Corresponding author)Extern*DESY*

2025

This record in other databases:    

Please use a persistent id in citations: doi:10.3204/PUBDB-2025-04772

Report No.: DESY-25-162; arXiv:2512.21328

Abstract: Gravitational waves provide a unique window into gravity, cosmology, and high-energy physics, enabling the exploration of fundamental phenomena across a wide range of scales. This review presents a coherent and pedagogical framework that bridges foundational theory with observational frontiers. We begin by developing the theory of gravitational radiation within linearized general relativity, deriving gravitational waves as solutions to the linearized Einstein equations and clarifying their physical interpretation, polarization states, and key properties. We then deepen the discussion through a geometric perspective, tracing the connection between gravitational radiation and the algebraic structure of the Weyl tensor and its role in defining energy and angular momentum in asymptotically flat spacetimes. Extending beyond flat backgrounds, we examine gravitational waves in an expanding universe, following their evolution across cosmological epochs and their generation during inflation. Within this setting, we discuss adiabatic modes and consistency relations that reveal universal properties of long-wavelength perturbations, and derive the inflationary spectrum of vacuum gravitational waves together with their contribution to the integrated Sachs-Wolfe effect. We also survey the main observational strategies for detecting gravitational waves across a broad frequency range, including cosmic microwave background polarization, pulsar timing arrays, ground- and space-based laser interferometers, and resonant cavity detectors. We then discuss the astrophysical and cosmological mechanisms responsible for generating gravitational radiation. We conclude by summarizing the current status of the field and outlining promising directions for future theoretical and observational developments.

Note: 118 Pages, 41 Figs, Invited review for The Astronomy and Astrophysics Review. Comments are welcome

---

Contributing Institute(s):

1. Theorie-Gruppe (T)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)
2. DFG project G:(GEPRIS)390833306 - EXC 2121: Das Quantisierte Universum II (390833306) (390833306)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2025

---

Database coverage:

---