Effects of dynamical friction on perturbations for evolving dark energy
Pace F. Luongo O. Del Popolo A.
May 2025Elsevier B.V.
Physics of the Dark Universe
2025#48
We explore the impact of dynamical friction on scales where the linear growth factor and the spherical collapse model can be applied and show its influence on the evolution of perturbations. In particular, considering smooth and clustering dark energy models, we describe the role played by friction by selecting two main hierarchical models, i.e., the first where the friction term is proportional to the Hubble rate, whereas the second where friction is induced by the dark energy pressure. The second approach generalizes the first and translates the idea that pressure is a general relativistic effect, motivating why friction might arise once barotropic dark energy fluids are considered. The corresponding effects of friction are investigated at the level of linear and nonlinear perturbations, using the formalism of the spherical collapse model. Whilst dynamical friction has very small effects and thus it cannot be excluded a priori, dissipative pressure friction leads to a substantial slow down in the evolution of perturbations. This can be inferred particularly from the halo mass function, for which we also employ corrections due to dark energy clustering. To this end, in order to discern detectable deviations from the standard cosmological model, we thus highlight where dissipation effects might play a significant role at large scales.
Cosmology , Dark energy , Dynamical friction , Spherical collapse
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Dipartimento di Fisica, Università degli Studi di Torino, Via P. Giuria 1, Torino, I-10125, Italy
INFN-Sezione di Torino, Via P. Giuria 1, Torino, I-10125, Italy
INAF-Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Torino, strada Osservatorio 20, Pino Torinese, 10025, Italy
Department of Mathematics and Physics, SUNY Polytechnic Institute, 100 Seymour Rd, Utica, 13502, NY, United States
Divisione di Fisica, Università degli studi di Camerino, Via Madonna delle Carceri 9B, Camerino, 62032, Italy
INFN-Sezione di Perugia, Via Alessandro Pascoli 23c, Perugia, 06123, Italy
Al-Farabi Kazakh National University, Al-Farabi Avenue 71, Almaty, 050040, Kazakhstan
Dipartimento di Fisica e Astronomia, University of Catania, Viale Andrea Doria 6, Catania, 95125, Italy
INFN-Sezione di Catania, Via Santa Sofia 64, Catania, 95123, Italy
Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya str., 48, Moscow, 119017, Russian Federation
Dipartimento di Fisica
INFN-Sezione di Torino
INAF-Istituto Nazionale di Astrofisica
Department of Mathematics and Physics
Divisione di Fisica
INFN-Sezione di Perugia
Al-Farabi Kazakh National University
Dipartimento di Fisica e Astronomia
INFN-Sezione di Catania
Institute of Astronomy
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