Eur. Phys. J. C (2024) 84: 912
https://doi.org/10.1140/epjc/s10052-024-13267-7

Regular Article - Theoretical Physics

Testing the coupling of dark radiations in light of the Hubble tension

¹ Department of Astronomy, School of Physical Sciences, University of Science and Technology of China, 230026, Hefei, Anhui, China
² School of Astronomy and Space Science, University of Science and Technology of China, 230026, Hefei, Anhui, China
³ CAS Key Laboratory for Researches in Galaxies and Cosmology, University of Science and Technology of China, 230026, Hefei, Anhui, China
⁴ Kavli IPMU (WPI), UTIAS The University of Tokyo, 5-1-5 Kashiwanoha, 277-8583, Kashiwa, Chiba, Japan
⁵ Department of Computer Science, Mohammad Ali Jinnah University, Block-6, P.E.C.H.S, Karachi-75400 Sindh, Pakistan

^a zhiyulu@mail.ustc.edu.cn

Received: 3 January 2024
Accepted: 18 August 2024
Published online: 9 September 2024

Abstract

We are studying the effects of Self-Interacting dark radiation (SIdr) on the evolution of the universe. Our main focus is on the cosmic microwave background (CMB) and how SIdr could potentially help resolve the Hubble tension. We are looking into different scenarios by mixing SIdr with Free-Streaming dark radiation (FSdr) or not to determine whether SIdr can indeed contribute to solving the Hubble tension. We find that SIdr alone can increase the Hubble constant ($H_0$) to $70.1_{-1.6}^{+1.3},\text{km/s/Mpc}$ with a value of $N_{\text{eff}}=3.{27}_{-0.31}^{+0.23}$. However, including FSdr disfavors the existence of SIdr ${\tilde{N}}_{\text{si}}\approx 0.37$. Even though the Hubble constant is increased compared to the predicted value, it entails $N_{\text{eff}}=3.52\pm 0.25$. Finally, we implement the Fisher method for future experiments and a $7.64\sigma$ measurement of ${\tilde{N}}_{\text{si}}$ will be obtained when combing data from Planck, AliCPT, and CMB-S4.