Indico has been updated to v3.3. See our blog post for details on this release. (OTG0146394)

May 16 – 19, 2023
Texas A&M University
US/Central timezone

Stepped Partially Acoustic Dark Matter (SPartAcous)

May 16, 2023, 5:30 PM
Hawking Auditorium (Texas A&M University)

Hawking Auditorium

Texas A&M University


Taewook Youn (University of Texas at Austin)


In this talk, we present a new interacting dark sector model, Stepped Partially Acoustic Dark Matter (SPartAcous), that can tackle two major issues in current cosmological data, namely the $H_0$ and $S_8$ problems. Similar to Partially Acoustic Dark Matter (PAcDM), this model involves a part of dark matter that interacts with dark radiation at high temperatures, resulting in a decrease in the formation of structure at small scales and thus, solving the $S_8$ problem. However, in the SPartAcous model, the dark radiation comprises a light component that becomes non-relativistic near the time of matter-radiation equality. As this light component annihilates, the remaining dark radiation warms up, leading to a step-like increase in the relative energy density in dark radiation. This step-like increase significantly mitigates the $H_0$ tension. Moreover, dark matter and dark radiation become decoupled, ensuring that the power spectrum at larger scales is similar to that of $\Lambda$CDM.

Primary author

Taewook Youn (University of Texas at Austin)

Presentation materials