Investigating Cosmological Models and the Hubble Tension Using Localized Fast Radio Bursts

Jun Jie Wei, Fulvio Melia

Research output: Contribution to journalArticlepeer-review

Abstract

We use the dispersion measure (DM) and redshift measurements of 24 localized fast radio bursts (FRBs) to compare cosmological models and investigate the Hubble tension. Setting a flat prior on the DM contribution from the Milky Way’s halo, DM halo MW ∈ [ 5 , 80 ] pc cm − 3 , the best fit for flat ΛCDM is obtained with a Hubble constant H 0 = 95.8 − 9.2 + 7.8 km s − 1 Mpc − 1 and a median matter density Ωm ≈ 0.66. The best fit for the R h = ct universe is realized with H 0 = 94.2 − 6.2 + 5.6 km s − 1 Mpc − 1 . We emphasize that the H 0 measurement depends sensitively on the DM halo MW prior. Since flat ΛCDM has one more free parameter, R h = ct is favored by the Bayesian Information Criterion (BIC) with a likelihood of ∼73% versus ∼27%. Through simulations, we find that if the real cosmology is ΛCDM, a sample of ∼1150 FRBs in the redshift range 0 < z < 3 would be sufficient to rule out R h = ct at a 3σ confidence level, while ∼550 FRBs would be necessary to rule out ΛCDM if the real cosmology is instead R h = ct. The required sample sizes are different, reflecting the fact that the BIC imposes a severe penalty on the model with more free parameters. We further adopt a straightforward method of deriving an upper limit to H 0, without needing to consider the poorly known probability distribution of the DM contributed by the host galaxy. The theoretical DM contribution from the intergalactic medium (DMIGM) at any z is proportional to H 0. Thus, requiring the extragalactic DMext to be larger than DMIGM delimits H 0 to the upside. Assuming flat ΛCDM, we have H 0 < 89.0 km s−1 Mpc−1 at a 95% confidence level.

Original languageEnglish (US)
Article number101
JournalAstrophysical Journal
Volume955
Issue number2
DOIs
StatePublished - Oct 1 2023

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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