2017/07/31 by Kyu Jung Bae, Ayuki Kamada, Seng Pei Liew +1
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #Dark Matter and Cosmic Phenomena #Dark matter #Distribution (mathematics) #Entropy production #Higgsino #Particle physics theoretical and experimental studies #Phase space #Spectral line #Warm dark matter #astro-ph.CO #hep-ph
paper · pdf · doi:10.1088/1475-7516/2018/01/054
published as JCAP 01 (2018) 054 · published version with appendix D added; typos corrected
openalex created_date 2017/07/31 · openalex publication_date 2018/01/31 · arxiv created 2020/06/01 · arxiv updated 2020/06/02 · openalex updated_date 2026/08/05
We consider the freeze-in production of 7 keV axino dark matter (DM) in the supersymmetric Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model in light of the 3.5 keV line excess. The warmness of such 7 keV DM produced from the thermal bath, in general, appears in tension with Ly-α forest data, although a direct comparison is not straightforward. This is because the Ly-α forest constraints are usually reported on the mass of the conventional warm dark matter (WDM), where large entropy production is implicitly assumed to occur in the thermal bath after WDM particles are decoupled. The phase space distribution of freeze-in axino DM varies depending on production processes and axino DM may alleviate the tension with the tight Ly-α forest constraints. By solving the Boltzmann equation, we first obtain the resultant phase space distribution of axinos produced by 2-body decay, 3-body decay, and 2-to-2 scattering respectively. The reduced collision term and resultant phase space distribution are useful for studying other freeze-in scenarios as well. We then calculate the resultant linear matter power spectra for such axino DM and directly compare them with the linear matter power spectra for the conventional WDM . In order to demonstrate realistic axino DM production, we consider benchmark points with Higgsino next-to-light supersymmetric particle (NLSP) and wino NLSP. In the case of Higgsino NLSP, the phase space distribution of axinos is colder than that in the conventional WDM case, so the most stringent Ly-α forest constraint can be evaded with mild entropy production from saxion decay inherent in the supersymmetric DFSZ axion model.