Kavli Affiliate: Kiyoshi W. Masui
| First 5 Authors: Calvin Leung, Calvin Leung, , ,
| Summary:
Low redshift fast radio bursts (FRBs) provide robust measurements of the
host-galaxy contribution to the dispersion measure (DM), which can constrain
the circumgalactic medium (CGM) of the hosts. We curate a sample of 20 nearby
FRBs with low scattering timescales and face-on host galaxies with stellar
masses ranging from $10^9 < M^* / M_odot < 10^11$. We fit the distribution
of the host galaxy DM to a quadratic model as a function of stellar mass with a
mass-independent scatter and find that the more massive the host, the lower its
host DM. We report that this relation has a negative slope of $m = -97 pm 44$
pc/cm$^-3$ per dex in stellar mass. We compare this measurement to similar
fits to three sub-grid models implemented in the CAMELS suite of simulations
from Astrid, IllustrisTNG, and SIMBA and find that fine-tuning of the host ISM
contribution as a function of stellar mass is required in order to reconcile
the observational data with the predictions of the fiducial CAMELS-Astrid
model. More generally, models which attribute a positive correlation between
stellar mass and host dispersion measure ($m > 0$) to the CGM are in tension
with our measurement. 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 sightline.
Our results indirectly imply a lower limit on the strength of baryonic feedback
in the Local Universe $(z < 0.2)$ in isolated $sim L^*$ halos, complementing
results from weak lensing surveys and kSZ observations which target higher halo
mass and redshift ranges.
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