Probing the Universe with Fast Radio Bursts

Abstract

Fast Radio Bursts (FRBs) represent a novel tool for probing the properties of the universe at cosmological distances. The dispersion measures of FRBs, combined with the redshifts of their host galaxies, has very recently yielded a direct measurement of the baryon content of the universe, and has the potential to directly constrain the location of the “missing baryons”. The first results are consistent with the expectations of ΛCDM for the cosmic density of baryons, and have provided the first constraints on the properties of the very diffuse intergalactic medium (IGM) and circumgalactic medium (CGM) around galaxies. FRBs are the only known extragalactic sources that are compact enough to exhibit diffractive scintillation in addition to showing exponential tails which are typical of scattering in turbulent media. This will allow us to probe the turbulent properties of the circumburst medium, the host galaxy ISM/halo, and intervening halos along the path, as well as the IGM. Measurement of the Hubble constant and the dark energy parameter w can be made with FRBs, but require very large samples of localised FRBs (>103) to be effective on their own—they are best combined with other independent surveys to improve the constraints. Ionisation events, such as for He ii, leave a signature in the dispersion measure—redshift relation, and if FRBs exist prior to these times, they can be used to probe the reionisation era, although more than 103 localised FRBs are required.

Characterizing the FRB host galaxy population and its connection to transients in the local and extragalactic Universe

“…While the nature of FRBs remains uncertain, the redshifts for localized FRBs still permit us to probe the baryonic content of the Universe (Macquart et al 2020), through measurements of the ionised baryon density in the intergalactic medium (IGM). FRBs are thus excellent probes of cosmology and the structure of the Universe (Bhandari & Flynn 2021).…”

An 8\% Determination of the Hubble Constant from localized Fast Radio Bursts

“…In particular, DM IGM , contributed by the intergalactic medium (IGM), has a close connection with cosmological parameters. Therefore, precise measurements of DM IGM can be used as cosmological probes (Xiao et al 2021;Bhandari & Flynn 2021), such as "missing" baryons (McQuinn 2014Macquart et al 2020), cosmic proper distance (Yu & Wang 2017), dark energy (Zhou et al 2014;Gao et al 2014;Walters et al 2018), Hubble constant (Hagstotz et al 2021) and reionization history (Zheng et al 2014;Zhang et al 2021). Strongly lensed FRBs have been proposed to probe the nature of dark matter (Muñoz et al 2016;, and measure Hubble constant (Li et al 2018).…”

A forecast of using fast radio burst observations to constrain holographic dark energy

“…Then we turn our attention to the constraints on the baryon density Ω b and the Hubble constant H 0 . Using big bang nucleosynthesis (BBN) and CMB can precisely determine the value of Ω b h 2 , however, in the nearby universe, the observed baryons in stars, the cold interstellar medium, residual Lyα forest gas, O vi, broad H i Lyα absorbers, and hot gas in clusters of galaxies account for only ∼ 50% of the baryons [55]. This is called the missing baryon problem.…”