Simulated Dispersion Measures of the Intergalactic Medium

  • Henry Adams

Student thesis: Master of Science by Research


Fast radio bursts (FRBs) can be observed by their large dispersion in time across the different frequencies from which they are made. This dispersion measure (DM) depends on the number of electrons along its path. This allows them to act as a cosmological probe for gas in the intergalactic medium (IGM) and may be used to investigate the missing baryon problem, in which a discrepancy between the predicted and observed baryon densities have been found. We have used the Evolution and Assembly of GaLaxies and their Environments (EAGLE) simulation to simulate the DM from FRBs using a box stacking method and find the mean DM - z relation to follow the cosmological average. We found the scatter of the result to be significantly non Gaussian, being better represented by a log-normal distribution and that observations broadly agree with the results. We also examined the effect of host haloes by setting sight lines to start at the centre of haloes of different mass. We find that haloes play a significant role in the DM at lower redshifts but become less important at larger distances. Finally we examined the contributions from different gas overdensities of the IGM and found the overdense group contributes the most to the DM, and that the DM contribution drops off significantly with increasing overdensity.
Date of Award31 Dec 2021
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorNeal Jackson (Supervisor) & Scott Kay (Supervisor)


  • Astrophysics - Cosmology and Nongalactic Astrophysics
  • cosmology: theory

Cite this