Year: 2020
Type: article
Abstract: The effective theory of large-scale structure formation based on $$\Lambda $$ Λ CDM paradigm predicts finite dissipative effects in the resulting fluid equations. In this work, we study how viscous effect that could arise if one includes self-interaction among the dark-matter particles combines with the effective theory. It is shown that these two possible sources of dissipation can operate together in a cosmic fluid and the interplay between them can play an important role in determining dynamics of the cosmic fluid. In particular, we demonstrate that the viscosity coefficient due to self-interaction is added inversely with the viscosity calculated using effective theory of $$\Lambda $$ Λ CDM model. Thus the larger viscosity has less significant contribution in the effective viscosity. Using the known bounds on $$\sigma /m$$ σ/m for self-interacting darkmatter, where $$\sigma $$ σ and m are the cross-section and mass of the dark-matter particles respectively, we discuss role of the effective viscosity in various cosmological scenarios.
Source: The European Physical Journal C
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W2955630842