[Paper Review] Listening to the Universe with Next Generation Ground-Based Gravitational-Wave Detectors

Ssohrab Borhanian, B. S. Sathyaprakash|arXiv (Cornell University)|Feb 22, 2022

Pulsars and Gravitational Waves ResearchPhysics and Astronomy24 citations

TL;DR

The paper assesses science capabilities of future ground-based GW detector networks (A+, Voyager, NG like CE and ET) using Fisher analysis to forecast detection, localization, and multimessenger potential for BNS and BBH mergers.

ABSTRACT

In this study, we use simple performance metrics to assess the science capabilities of future ground-based gravitational-wave detector networks -- composed of A+ or Voyager upgrades to the LIGO, Virgo, and KAGRA observatories and proposed next generation observatories such as Cosmic Explorer and Einstein Telescope. These metrics refer to coalescences of binary neutron stars (BNSs) and binary black holes (BBHs) and include: (i) network detection efficiency and detection rate of cosmological sources as a function of redshift, (ii) signal-to-noise ratios and the accuracy with which intrinsic and extrinsic parameters would be measured, and (iii) enabling multimessenger astronomy with gravitational waves by accurate 3D localization and early warning alerts. We further discuss the science enabled by the small population of rare and extremely loud events. While imminent upgrades will provide impressive advances in all these metrics, next generation observatories will deliver an improvement of an order-of-magnitude or more in most metrics. In fact, a network containing two or three such facilities will detect half of all the BNS and BBH mergers up to a redshift of $z=1$ and $z=20$, respectively, give access to hundreds of BNSs and ten thousand BBHs with signal-to-noise ratios exceeding 100, readily localize hundreds to thousands of mergers to within $1\,{ m deg^2}$ on the sky and better than 10% in luminosity distance, respectively, and consequently, enable mutlimessenger astronomy through follow-up surveys in the electromagnetic spectrum several times a week. Such networks will further shed light on potential cosmological merger populations and detect an abundance of high-fidelity BNS and BBH signals which will allow investigations of the high-density regime of matter at an unprecedented level and enable precision tests of general relativity in the strong-field regime, respectively.

Motivation & Objective

• Assess the science capabilities of future GW detector networks comprising A+, Voyager, and next-generation observatories (CE and ET).
• Evaluate network performance metrics including detection efficiency, SNRs, parameter estimation, and 3D localization for BNS and BBH mergers.
• Quantify potential for multimessenger astronomy with early warning alerts and sky localization.
• Explore science opportunities from rare, highly loud GW events and implications for GR tests and dense-matter physics.

Proposed method

• Model detector networks and source populations (BNS and BBH) with specified masses, spins, and orientations.
• Use the Fisher-information framework via gwbench to estimate parameter errors and SNRs for network configurations.
• Compute network SNR and detection efficiency as a function of redshift using Eq. (2) and the sigmoid fit in Eq. (4).
• Simulate sky localization and early-warning capabilities, including 3D localization and precursor alerts for mergers.
• Adopt IMRPhenomD_NRTidalv2 for BNS and IMRPhenomHM for BBH waveform modeling in the Fisher analysis.
• Examine reach and horizon redshift for each network and derive detection rates across redshift bins.

Experimental results

Research questions

• RQ1 What performance gains do A+, Voyager, and NG detector networks offer for BNS and BBH detections?
• RQ2 How do network configurations affect SNR distributions, parameter estimation accuracy, and sky localization?
• RQ3 What are the reach and horizon redshifts for different networks, and how do these translate to rates and multimessenger prospects?
• RQ4 How feasible is early warning and 3D localization for enabling electromagnetic follow-up?
• RQ5 What science opportunities arise from rare, high-SNR GW events in these networks?

Key findings

• Next-generation networks (NG) will improve most metrics by an order of magnitude or more compared to current upgrades.
• A network with two or three NG facilities can detect about half of all BNS mergers up to z=1 and BBH mergers up to z=20.
• NG networks can localize hundreds to thousands of mergers to within 1 deg^2 and measure luminosity distances to better than 10% for many events.
• Voyager networks will reach BBH mergers to z~10 and BNS mergers to z~0.9 with substantial SNR (>100 for many events).
• NG networks will enable multimessenger astronomy through frequent follow-up surveys and will enable precision tests of GR and dense-matter physics.