How can gravitational-wave standard sirens and 21 cm intensity mapping jointly provide a precise late-universe cosmological probe?

• Published in: arXiv.org
• Main Authors: Shang-Jie, Jin, Ling-Feng, Wang, Peng-Ju, Wu, Jing-Fei, Zhang, Zhang, Xin
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 12.11.2021
• Subjects: Arrays; Constraint modelling; Cosmology; Gravitational waves; Mapping; Model accuracy; Parameter estimation; Physics - Cosmology and Nongalactic Astrophysics; Physics - General Relativity and Quantum Cosmology; Physics - High Energy Physics - Phenomenology; Sirens
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2106.01859

In the next decades, the gravitational-wave (GW) standard siren observations and the neutral hydrogen 21-cm intensity mapping (IM) surveys, as two promising cosmological probes, will play an important role in precisely measuring cosmological parameters. In this work, we make a forecast for cosmological parameter estimation with the synergy between the GW standard siren observations and the 21-cm IM surveys. We choose the Einstein Telescope (ET) and the Taiji observatory as the representatives of the GW detection projects and choose the Square Kilometre Array (SKA) phase I mid-frequency array as the representative of the 21-cm IM experiments. In the simulation of the 21-cm IM data, we assume perfect foreground removal and calibration. We find that the synergy of the GW standard siren observations and the 21-cm IM survey could break the cosmological parameter degeneracies. The joint ET+Taiji+SKA data give \(\sigma(H_0)=0.28\ {\rm km\ s^{-1}\ Mpc^{-1}}\) in the \(\Lambda\)CDM model, \(\sigma(w)=0.028\) in the \(w\)CDM model, which are better than the results of \(Planck\)+BAO+SNe, and \(\sigma(w_0)=0.077\) and \(\sigma(w_a)=0.295\) in the CPL model, which are comparable with the results of \(Planck\)+BAO+SNe. In the \(\Lambda\)CDM model, the constraint precision of \(H_0\) and \(\Omega_{\rm m}\) is less than or rather close to 1%, indicating that the magnificent prospects for precision cosmology with these two promising cosmological probes are worth expecting.