Speaker
Description
The distribution of cosmological baryons remains incompletely understood despite recent progress using fast radio bursts (FRBs). Dispersion measures (DM) trace the integrated ionized baryon content along the line of sight, but uncertainties in the host-galaxy contribution ($\mathrm{DM}_{\rm host}$) limit the statistical significance of correlations between intergalactic DM and large-scale structure. We aim to improve constraints on baryonic fluctuations by reducing uncertainties in the host-galaxy DM. We estimate $\mathrm{DM}_{\rm host}$ individually using H$\alpha$ emission from FRB host galaxies, providing a physically motivated measurement of ionized gas content. Using this, we derive the cosmic DM component and its deviation ($\Delta \mathrm{DM}_{\rm cosmic}$). We then measure foreground galaxy number densities within cylindrical volumes of 5~Mpc proper radius along each FRB line of sight, extending to the FRB redshift, using the WISE--PS1 photometric redshift catalog. Galaxy densities are compared with randomly generated control sightlines. We find a positive correlation between $\Delta \mathrm{DM}_{\rm cosmic}$ and foreground galaxy density with improved statistical significance ($p = 0.0035$), compared to previous studies ($p = 0.01$). Our results provide stronger evidence that baryons trace large-scale structure, with excess baryons in overdense regions and deficits in underdense regions. This demonstrates that accurate $\mathrm{DM}_{\rm host}$ estimation is essential for establishing FRBs as reliable probes of the cosmological baryon distribution.
| Participate the oral/poster presentation award competition | Yes |
|---|