查看“Hubble tension”的源代码

* ArXiv:2406.15548
Given the abundance of precision cosmological data now avail�able, modifications to the standard ΛCDM that do not conflict with
observations are surprisingly difficult to realize. The “least unlikely”
type of modification that is allowed (Knox & Millea 2020) increases
the expansion rate of the Universe before recombination. This modi�fication decreases the physical sound horizon measured by the CMB,
requiring an attendant decrease in the distance to the last scattering
that is obtained through an increase in 𝐻0. One possible mechanism
for achieving this increased expansion at early times is “Early Dark
Energy” (EDE), where a new cosmological energy source with an
equation of state similar to dark energy contributes ∼ 10% of the crit�ical density at its time of maximal contribution (𝑧 ∼ 3000; see Poulin
et al. 2023 for a recent review).