Fast Radio Bursts and Cosmology: a model-independent investigation
Name: JÉFERSON ANDRÉ SALES FORTUNATO
Publication date: 07/05/2025
Examining board:
Name |
Role |
|---|---|
| WILIAM SANTIAGO HIPOLITO RICALDI | Presidente |
Pages
Summary: The last two decades have witnessed tremendous progress in observational cosmology,
yet some of the most fundamental questions surrounding the current concordance model,
CDM, remain unresolved. Among them are the nature of the accelerated expansion,
the true geometry of spacetime, and persistent discrepancies in measurements of the
Hubble constant. In parallel, the discovery of Fast Radio Bursts (FRBs) — enigmatic
millisecond-duration transients of extragalactic origin — has opened an unexpected
window into the large-scale structure of the Universe. In this thesis, we investigate
the potential of FRBs as cosmological probes through a fully model-independent ap-
proach. We begin by reformulating the dispersion measure–redshift relation within the
framework of cosmography, enabling the extraction of kinematic parameters without
relying on a specific background model. This approach yields competitive constraints
on H0 and provides evidence for late-time cosmic acceleration using only current FRB
data. We then apply Artificial Neural Networks (ANNs) to reconstruct the expansion
history directly from FRB observations. This allows us to estimate the Hubble param-
eter H(z) and the Hubble constant H0 with minimal assumptions, and to assess the
performance of our model, we tested it against simulated data. Finally, we develop a
new strategy to constrain the spatial curvature of the Universe by combining comoving
distances inferred from FRBs with angular diameter distances from BAO, avoiding as-
sumptions about any specific cosmological model. Altogether, this work demonstrates
the viability of FRBs as standalone cosmological observables. The methods developed
here show that even with current datasets, FRBs can provide meaningful constraints on
fundamental parameters, and that future observations will significantly enhance their
impact. This positions FRBs as powerful tools in the era of precision cosmology.
