The majority of the matter in the Universe can not be found inside galaxies. Instead, most of the mass of the Universe resides in the low-density, highly ionised region outside of galaxies known as the Intergalactic Medium (IGM). Approximately 80% of baryons in the present-day Universe are located in the IGM. The fact that the IGM contains the vast majority of the mass of the Universe means it is a crucial component to study if we wish to have a complete understanding of the evolution of matter.
The IGM is tightly linked to the evolution of stars and galaxies. The IGM provides the initial conditions from which a galaxy grows and is the reservoir of pristine gas which galaxies accrete to form new stars. The intertwined nature of galaxy evolution and the IGM means it is impossible to disentangle them and study them individually. To understand one, we must understand the other. However, the IGM isn’t so easy to observe. The high-temperatures and low-densities make observations in the optical and UV extremely unfavourable.
Image Credit: James Josephides / Swinburne University of Technology.
Fast radio bursts (FRBs) are a class of bright, millisecond, extragalactic radio transients. In the short time since their discovery in 2007, they already appear to be a valuable tool for studying the Universe. The critical property of FRBs is their dispersion measure (DM) which is extremely sensitive to the total number of electrons along their line-of-sight. Due to the extragalactic nature of FRBs, their dispersion measure makes them an excellent probe of the highly ionised plasma that fills the intergalactic medium.
My list of publications are also avaliable on ADS, via my ORCID page and google scholar.
Batten, A. J., et al., “Fast radio bursts as probes of feedback from active galactic nuclei”, Monthly Notices of the Royal Astronomical Society: Letters, vol. 512, iss. 1, May 2022, Pages L49-L53, https://doi.org/10.1093/mnrasl/slac020
Batten, A. J., et al., “The cosmic dispersion measure in the EAGLE simulations”, Monthly Notices of the Royal Astronomical Society, vol. 505, iss. 4, August 2021, Pages 5356–5369, https://doi.org/10.1093/mnras/stab1528
Batten, A. J., “Fruitbat: A Python Package for Estimating Redshifts of Fast Radio Bursts”, The Journal of Open Source Software, vol. 4, no. 37, 2019. https://doi.org/10.21105/joss.01399.
FRUITBAT is an open source fast radio burst (FRB) redshift estimation package written in Python. Repo on Github