Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Sources of Gravitational Waves: Theory and Observations

Alessandra Buonanno, B. S. Sathyaprakash

TL;DR

The chapter surveys the origins and detection prospects of gravitational waves, outlining the theoretical foundations (post-Newtonian, perturbation/self-force, EFT, and effective-one-body) and the pivotal role of numerical relativity in waveform modeling. It details GW sources across binaries, isolated neutron stars, and early-Universe backgrounds, highlighting how analytical and numerical methods are integrated to produce robust waveform templates for current and future detectors such as LIGO/Virgo/KAGRA, LISA/eLISA, ET, and PTAs. Key contributions include the synthesis of PN and NR results via EOB and other frameworks, the treatment of extreme-mass-ratio inspirals, and the prospects for multi-messenger and cosmological applications through standard sirens and GW spectroscopy. The work underscores the synergy between theory and observation as essential for maximizing detections, extracting astrophysical and fundamental-physics information, and testing gravity in the strong-field regime, with significant implications for astrophysics, cosmology, and fundamental physics.

Abstract

Gravitational-wave astronomy will soon become a new tool for observing the Universe. Detecting and interpreting gravitational waves will require deep theoretical insights into astronomical sources. The past three decades have seen remarkable progress in analytical and numerical computations of the source dynamics, development of search algorithms and analysis of data from detectors with unprecedented sensitivity. This Chapter is devoted to examine the advances and future challenges in understanding the dynamics of binary and isolated compact-object systems, expected cosmological sources, their amplitudes and rates, and highlights of results from gravitational-wave observations. All of this is a testament to the readiness of the community to open a new window for observing the cosmos, a century after gravitational waves were first predicted by Albert Einstein.

Sources of Gravitational Waves: Theory and Observations

TL;DR

The chapter surveys the origins and detection prospects of gravitational waves, outlining the theoretical foundations (post-Newtonian, perturbation/self-force, EFT, and effective-one-body) and the pivotal role of numerical relativity in waveform modeling. It details GW sources across binaries, isolated neutron stars, and early-Universe backgrounds, highlighting how analytical and numerical methods are integrated to produce robust waveform templates for current and future detectors such as LIGO/Virgo/KAGRA, LISA/eLISA, ET, and PTAs. Key contributions include the synthesis of PN and NR results via EOB and other frameworks, the treatment of extreme-mass-ratio inspirals, and the prospects for multi-messenger and cosmological applications through standard sirens and GW spectroscopy. The work underscores the synergy between theory and observation as essential for maximizing detections, extracting astrophysical and fundamental-physics information, and testing gravity in the strong-field regime, with significant implications for astrophysics, cosmology, and fundamental physics.

Abstract

Gravitational-wave astronomy will soon become a new tool for observing the Universe. Detecting and interpreting gravitational waves will require deep theoretical insights into astronomical sources. The past three decades have seen remarkable progress in analytical and numerical computations of the source dynamics, development of search algorithms and analysis of data from detectors with unprecedented sensitivity. This Chapter is devoted to examine the advances and future challenges in understanding the dynamics of binary and isolated compact-object systems, expected cosmological sources, their amplitudes and rates, and highlights of results from gravitational-wave observations. All of this is a testament to the readiness of the community to open a new window for observing the cosmos, a century after gravitational waves were first predicted by Albert Einstein.

Paper Structure

This paper contains 52 sections, 24 equations, 9 figures, 2 tables.

Table of Contents

  1. Sources of Gravitational Waves: Theory and Observations
  2. Historical perspective
  3. Analytical approximation methods
  4. Progress over the past three decades:
  5. Physical scales and methods in the two-body problem:
  6. Post-Newtonian formalism
  7. The multipolar post-Minkowskian--post-Newtonian formalism:
  8. Wave-zone multipolar post-Minkowskian approximation:
  9. Near-zone post-Newtonian approximation:
  10. Direct integration of the relaxed Einstein equations:
  11. Gravitational waveform in the wave zone:
  12. Gravitational-wave flux at infinity:
  13. Gravitational radiation reaction:
  14. Advances in regularisation method:
  15. Canonical Hamiltonian approach:
  16. ...and 37 more sections

Figures (9)

  • Figure 1: Current range of validity of the main analytical and numerical methods to solve the two-body problem.
  • Figure 2: Schematic diagram of an inspiraling binary showing various scales used in the PN formalism.
  • Figure 3: The real and effective descriptions in the EOB formalism.
  • Figure 4: Gravitational waveform (upper panel), GW and twice orbital-angular frequencies (lower panel) from inspiral, plunge, merger and ringdown stages of a non-spinning, equal-mass binary BH as predicted in the EOB approach Buonanno:1998ggBuonanno:2000ef.
  • Figure 5: Frequency-mass diagram for equal-mass compact binaries.
  • ...and 4 more figures