[Paper Review] The Next Generation Global Gravitational Wave Observatory: The Science Book

Sub String Theory Cosmology and ElemPart, Theoretical Physics|Data Archiving and Networked Services (DANS)|Nov 12, 2021

Pulsars and Gravitational Waves ResearchPhysics and Astronomy47 citations

TL;DR

The paper advocates for a network of next-generation gravitational-wave detectors (ET and CE, plus LISA) and outlines the scientific goals across extreme matter, black holes, cosmology, gravity, and frontier sources, emphasizing multimessenger astronomy.

ABSTRACT

The next generation of ground-based gravitational-wave detectors will observe coalescences of black holes and neutron stars throughout the cosmos, thousands of them with exceptional fidelity. The Science Book is the result of a 3-year effort to study the science capabilities of networks of next generation detectors. Such networks would make it possible to address unsolved problems in numerous areas of physics and astronomy, from Cosmology to Beyond the Standard Model of particle physics, and how they could provide insights into workings of strongly gravitating systems, astrophysics of compact objects and the nature of dense matter. It is inevitable that observatories of such depth and finesse will make new discoveries inaccessible to other windows of observation. In addition to laying out the rich science potential of the next generation of detectors, this report provides specific science targets in five different areas in physics and astronomy and the sensitivity requirements to accomplish those science goals. This report is the second in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book (this report), iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network.

Motivation & Objective

• Motivate the development of next-generation gravitational-wave detectors to probe extreme matter, gravity, and fundamental physics.
• Explain how a global detector network will greatly extend observable volume, localization accuracy, and measurement precision.
• Highlight the role of multimessenger observations (electromagnetic, neutrino) in unlocking cosmology, nucleosynthesis, and astrophysical processes.
• Identify key science questions about neutron stars, black holes, early Universe, and potential new physics beyond general relativity.
• Outline the proposed detector concepts (Einstein Telescope and Cosmic Explorer) and their anticipated scientific impact.

Proposed method

• Propose a global network consisting of Einstein Telescope in Europe and Cosmic Explorer in the US and Australia.
• Explain the expected sensitivity improvements and expanded redshift reach relative to current detectors.
• Discuss science targets enabled by 3G detectors, including dense matter EOS, heavy-element production, and cosmology.
• Describe the complementarity of ground-based 3G detectors with space-based LISA for multi-band gravitational-wave astronomy.
• Outline anticipated detection rates, source demographics, and tests of gravity and exotic physics that will become possible.

Experimental results

Research questions

• RQ1 How will 3G detectors constrain the equation of state of dense matter and reveal quark/gluon phases in neutron-star cores?
• RQ2 What can multimessenger gravitational-wave observations reveal about heavy-element nucleosynthesis and the origin of cosmic abundances?
• RQ3 How will a global 3G GW network map black hole and neutron star populations across cosmic time and inform their formation channels?
• RQ4 To what extent can next-generation GW observations test general relativity and uncover new physics in strong-field gravity?
• RQ5 What are the prospects for detecting and characterizing stochastic and primordial gravitational-wave backgrounds with 3G detectors?

Key findings

• 3G detectors will achieve a substantial leap in sensitivity and sky-localization capability, enabling observations across vast cosmic volumes.
• A network of at least three detectors will enable precise localization and distance measurements needed for multimessenger follow-up.
• 3G observations will enable standard siren cosmology, tests of dense-matter physics, and insights into heavy-element production from neutron-star mergers.
• The combination of ground-based 3G detectors with LISA will enable multi-band gravitational-wave astronomy and broader astrophysical reach.
• 3G networks will detect mergers of stellar-mass black holes and neutron stars throughout cosmic history, offering unprecedented population studies and potential primordial black-hole investigations.
• The science case encompasses probing extreme gravity, fundamental physics, and the origins of the most energetic astrophysical phenomena.