Abstract Low-redshift fast radio bursts (FRBs) enable robust measurements of the host galaxy contribution to the dispersion measure (DM), offering valuable constraints on the circumgalactic medium (CGM) of FRB hosts. We curate a sample of 20 nearby FRBs with low scattering timescales and face-on host galaxies with stellar masses in the range 10 9 10 10.5 M ⊙ ). More generally, models that attribute a positive correlation between stellar mass and host DM ( m > 0) to the CGM are in tension with our measurement unless compensated by fine-tuning of the host interstellar medium contribution as a function of stellar mass, e.g., at the low-mass end. We show that this conclusion is robust to a wide range of assumptions, such as the offset distribution of FRBs from their hosts and the statistics of the cosmic contribution to the DM budget along each sight line. Our results indirectly imply a lower limit on the strength of baryonic feedback in the local Universe ( z < 0.2) in isolated ∼ L * halos, complementing results from weak-lensing surveys and kSZ observations that target higher halo mass and redshift ranges.
Leung et al. (Thu,) studied this question.
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