Kavli Affiliate: Chihway Chang
| First 5 Authors: Xianzhe TZ Tang, Dillon Brout, Tanvi Karwal, Chihway Chang, Vivian Miranda
| Summary:
Recent results from Type Ia Supernovae (SNe), baryon acoustic oscillations
(BAO), and the cosmic microwave background (CMB) indicate 1) potentially
discrepant measurements of the matter density $Omega_m$ and Hubble constant $
H_0 $ in $Lambda$CDM model when analyzed individually, and 2) hints of
dynamical dark energy in a $w_0w_a$CDM model when data are combined in a joint
analysis. We examine whether underlying dynamical dark energy cosmologies
favored by data would result in biases in $Omega_m$ and $ H_0 $ for each probe
when analyzed individually under $Lambda$CDM. We generate mock datasets in
$w_0w_a$CDM cosmologies, fit the individual probes under the $Lambda$CDM
model, and find expected biases in $Omega_m$ are $sim 0.03$. Notably, the
$Omega_m$ differences between probes are consistent with values observed in
real datasets. We also observe that mock DESI-BAO datasets generated in the
$w_0w_a$CDM cosmologies will lead to a biased measurement of $H_0$ higher by
($sim1.2$km/s/Mpc) when fitted under $Lambda$CDM, appearing to mildly improve
the Hubble tension, but as the true underlying $H_0$ is lower, the tension is
in fact worsened. We find that the $Omega_m$ discrepancies, the high BAO $ H_0
$ relative to CMB, and the joint dynamical dark energy signal are all related
effects that could be explained textit{simultaneously} with either new physics
or new systematics. While it is possible to unite many of the discrepancies
seen in recent analyses along a single axis, our results underscore the
importance of understanding systematic differences in datasets, as they have
unique impacts in different cosmological parameter spaces.
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