FRB cosmology with the RM-PRS Luminosity Correlation

TL;DR

The paper proposes a novel FRB cosmology method using the Yang-Li-Zhang RM–luminosity (YLZ) relation between FRB rotation measure and associated persistent radio source luminosity to calibrate FRBs as cosmological probes. It demonstrates that four YLZ-calibrated FRBs can constrain the Hubble constant, $H_0$, with $H_0 = 86.18_{-14.99}^{+18.03}$ km s$^{-1}$ Mpc$^{-1}$ (assuming a flat $\Lambda$CDM model), and forecasts that future catalogs of hundreds of FRB-PSR systems could reach about 4.5% precision. The study further shows that combining RM-based YLZ FRBs with the traditional DM–$z$ relation ($\mathrm{DM_{IGM}}$–$z$) via a joint likelihood can significantly improve constraints, potentially down to $\Delta H_0/H_0 \approx 2.9\%$ with balanced sample sizes, by mitigating degeneracies in $f_{\rm IGM}$ and other cosmological parameters. The work also discusses systematic uncertainties, such as foreground cluster RM contributions and DM modeling assumptions, and highlights the payoff of multi-probe FRB cosmology for upcoming facilities like SKA.

Abstract

Fast Radio Bursts (FRBs) have emerged as a powerful tool for cosmological studies, particularly through the dispersion measure-redshift ($\mathrm{DM}-z$) relation. This work proposes a novel calibration method for FRBs using the Yang-Li-Zhang (YLZ) empirical relation, which links the rotation measure (RM) of FRBs to the luminosity of their associated persistent radio sources (PRS). We demonstrate that this approach provides independent constraints on cosmological parameters, bypassing limitations inherent to traditional $\mathrm{DM}-z$ method. Utilizing the current sample of four YLZ-calibrated FRBs, we derive a Hubble constant measurement of $H_0 = 86.18_{-14.99}^{+18.03}\ \mathrm{km\ s^{-1}\ Mpc^{-1}}$ (68\% CL). Monte Carlo simulations indicate that a future catalog of 400 FRB-PSR systems could reduce the relative uncertainty of $H_0$ to 4.5\%. Combining YLZ-calibrated FRBs with $\mathrm{DM}-z$ sample reveals critical synergies: joint analysis of equalized samples ($N=100$ for both methods) reduces the relative uncertainty of $H_0$ to 2.9\%, mainly because the incorporation of PRS observations substantially mitigates the degeneracy between the parameters such as IGM baryon mass fraction ($f_{\rm IGM}$) and other cosmological parameters inherent to the $\mathrm{DM}-z$ relation.

Figures (5)

• Figure 1: Redshift distance modulus plot, orange is the result of the four FRB calculations given above, where the shaded band indicates their constrained $1\sigma$ confidence region, as a reference blue is the result of union2.1 Suzuki_2012.
• Figure 2: Probability density function of the Hubble constant derived from four FRB sources. Reference constraints from Planck 2020 and SH0ES Riess_2022 are indicated by red and green shaded regions.
• Figure 3: Redshift distance modulus plot, orange is the 400 simulated FRBs, where the shaded band indicates their constrained $1\sigma$ confidence region, as a reference blue is the result of union2.1 Suzuki_2012.
• Figure 4: Expected joint constraints on the Hubble constant $H_0$ and the matter density $\Omega_m$ contribution from 400 simulated FRBs as described in the text.
• Figure 5: This figure illustrates the $H_0$ constraints derived from multi-probe analyses of FRB data. The shaded regions represent PDFs from dispersion measure (DM)-only constraints: blue for the YMW16 Galactic electron density model and orange for NE2001. Solid lines denote joint constraints from observed DM and RM data, with green corresponding to YMW16 and red to NE2001. Dashed lines (purple: YMW16, brown: NE2001) show projected constraints from combining observed DM with simulated RM data.