The weak, the strong and the ugly – A comparative analysis of interacting stepped dark radiation
arxiv(2023)
摘要
Models which address both the Hubble and S_8 tensions with the same
mechanism generically cause a pre-recombination suppression of the small scale
matter power spectrum. Here we focus on two such models. Both models introduce
a self-interacting dark radiation fluid scattering with dark matter, which has
a step in its abundance around some transition redshift. In one model, the
interaction is weak and with all of the dark matter whereas in the other it is
strong but with only a fraction of the dark matter. The weakly interacting case
is able to address both tensions simultaneously and provide a good fit to a the
Planck measurements of the cosmic microwave background (CMB), the Pantheon Type
Ia supernovae, and a combination of low and high redshift baryon acoustic
oscillation data, whereas the strongly interacting model cannot significantly
ease both tensions simultaneously. The addition of high-resolution cosmic
microwave background (CMB) measurements (ACT DR4 and SPT-3G) slightly limits
both model's ability to address the Hubble tension. The use of the effective
field theory of large-scale structures analysis of BOSS DR12 LRG and eBOSS DR16
QSO data additionally limits their ability to address the S_8 tension. We
explore how these models respond to these data sets in detail in order to draw
general conclusions about what is required for a mechanism to address both
tensions. We find that in order to fit the CMB data the time dependence of the
suppression of the matter power spectrum plays a central role.
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