This content will become publicly available on June 1, 2024
 Award ID(s):
 1914679
 NSFPAR ID:
 10418315
 Publisher / Repository:
 Journal of High Energy Physics
 Date Published:
 Journal Name:
 Journal of High Energy Physics
 Volume:
 2023
 Issue:
 6
 ISSN:
 10298479
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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We propose a new interacting dark sector model, Stepped Partially Acoustic Dark Matter (SPartAcous), that can simultaneously address the two most important tensions in current cosmological data, the H0 and S8 problems. As in the Partially Acoustic Dark Matter (PAcDM) scenario, this model features a subcomponent of dark matter that interacts with dark radiation at high temperatures, suppressing the growth of structure at small scales and thereby addressing the S8 problem. However, in the SPartAcous model, the dark radiation includes a component with a light mass that becomes nonrelativistic close to the time of matterradiation equality. As this light component annihilates away, the remaining dark radiation heats up and its interactions with dark matter decouple. The heating up of the dark sector results in a steplike increase in the relative energy density in dark radiation, significantly reducing the H0 tension, while the decoupling of dark matter and dark radiation ensures that the power spectrum at larger scales is identical to ΛCDM.more » « less

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