Modeling the Cosmic Dispersion Measure in the D < 120 Mpc Local Universe

TL;DR

This paper presents a detailed, multi-component model of the dispersion measure in the local universe within 120 Mpc, integrating galaxy surveys, simulations, and observational data to improve understanding of cosmic baryon distribution.

Contribution

It introduces the most comprehensive local universe DM model to date, combining simulations and observational data, and provides it as an accessible Python package.

Findings

Most realistic DM model for the local universe to date

Enhanced potential for constraining intergalactic and circumgalactic medium contributions

Improved accuracy in cosmic baryon distribution estimates from FRB data

Abstract

The Local Universe (D < 120 Mpc) has been intensely studied for decades, with highly complete galaxy redshift surveys now publicly available. These data have driven density reconstructions of the underlying matter density field, as well as constrained simulations that aim to reproduce the observed structures. In this paper, we introduce a dispersion measure (DM) model that makes use of this detailed knowledge of our Local Universe within D < 120 Mpc. The model comprises three key components: (i) the DM from the Milky Way halo and the intra-group medium (up to 3.4 Mpc), derived from the HESTIA simulations, a series of constrained hydrodynamic simulations designed to reproduce our Local Group; (ii) the DM contribution from the large-scale intergalactic medium beyond the Local Group (3.4 Mpc < D < 120 Mpc), calculated using the HAMLET reconstructed matter density field; and (iii) the individual DM contributions from Local Universe galaxy halos and clusters based on data from the 2MASS Galaxy Group Catalog and the NASA/IPAC Extragalactic Database. This comprehensive model will be made available as a Python package. As the most realistic model to date for DM in the local volume, it promises to improve the constraints of DM contributions from the Intergalactic Medium and Circumgalactic Medium of FRBs, thereby enhancing the accuracy of cosmic baryon distribution calculations based on DM analysis of FRBs.