Forecasting constraints on the baryon mass fraction in the IGM from fast radio bursts and type Ia supernovae

Abstract

Fast Radio Bursts (FRBs) are transient events with a high energy and short duration in the radio frequency. By identifying the origin of the pulse, it is possible to measure the redshift of the host galaxy, which can be used to constrain cosmological and astrophysical parameters and test aspects of fundamental physics when combined with the observed dispersion measure ($DM$). However, some factors limit the application of FRBs in cosmology: (i) the current poor modelling of the fluctuations in the $DM$ due to spatial variation in the cosmic electrons density; (ii) the fact that the fraction of baryon mass in the intergalactic medium ($f_{IGM}$) is degenerated with some cosmological parameters; (iii) the limited current knowledge about host galaxy contribution ($DM_{host}$). In this work, we investigate the impact of different redshift distribution models of FRBs to constrain the baryon fraction in the IGM and host galaxy contribution. We use a cosmological model-independent method developed in previous work \cite{Lemos2023} to perform the analysis and combine simulated FRB data from Monte Carlo simulation and supernovae data. Since the physical mechanism responsible for the burst is still unknown, we assume four distribution models for the FRBs, namely gamma-ray bursts (GRB), star formation rate (SFR), uniform and equidistant (ED). Also, we consider samples with $N = 15$, 30, 100 and 500 points and three different values of the fluctuations of electron density in the $DM$, $\delta = 0, 10, 100$ pc/cm$^{3}$. Our analysis shows that the GRB, SFR and Uniform distribution models present consistent results within $2\sigma$ for the free parameters $f_{IGM}$ and $DM_{host,0}$ and highlights the crucial role of $DM$ fluctuations in obtaining more precise measurements.Comment: 9 pages, 2 figure