Oral Presentation

Studying the Cosmic Baryon Distribution with FRB Foreground Mapping

Author(s):

Presenter: Khee-Gan Lee (Kavli IPMU)

Despite their as-yet mysterious origins, the Fast Radio Bursts (FRBs) have became unique probes of various astrophysical and cosmological phenomena. For instance, the dispersion measure of FRBs were paramount in resolving the so-called 'missing baryon problem', yet the major questions remain regarding the relative distribution of cosmic baryons in the diffuse IGM tracing the cosmic web vs CGM of galactic halos. Unraveling the exact partition of cosmic baryons would inform models of galaxy formation and feedback mechanisms. I will show that it is possible to map out the cosmic distribution of CGM and IGM baryons by combining the localized FRB DMs with the spectroscopic redshift distribution of foreground galaxies, which dramatically increases the constraining power of FRB dispersion measures. I will describe FLIMFLAM, a 35-night spectroscopic survey on the Anglo-Australian Telescope (and other facilities) that has mapped the foregrounds of ~20-30 localized FRBs primarily detected by CRAFT/ASKAP and localized by the F^4 collaboration. I will present results from the FLIMFLAM's first data release. This is an analysis of 8 FRB sightlines to yield the first direct constraints on the relative partition of cosmic baryons between the CGM and IGM, as well as estimates of the average host galaxy contribution to the dispersion measure. I will also present preliminary forecasts for future samples of FRBs' ability to constrain the cosmic baryon distribution.