• shareshare
  • link
  • cite
  • add
auto_awesome_motion View all 2 versions
Publication . Article . Preprint . 2021

Singularities and Soft-Big Bang in a viscous $\Lambda$CDM model

Norman Cruz; Esteban González; Jose Jovel;
Open Access
Published: 20 Sep 2021

In this paper we explore the different types of singularities that arise in the $\Lambda$CDM model when dissipative processes are considered, in the framework of the Eckart's theory. In particular, we study the late-time behavior of $\Lambda$CDM model with viscous cold dark matter (CDM) and an early-time viscous radiation domination era with cosmological constant (CC). The fluids are described by the barotropic equation of state (EoS) $p=(\gamma-1)\rho$, where $p$ is the equilibrium pressure of the fluid, $\rho$ their energy density, and $\gamma$ is the barotropic index. We explore two particular cases for the bulk viscosity $\xi$, a constant bulk viscosity $\xi=\xi_{0}$, and a bulk viscosity proportional to the energy density of the fluid $\xi=\xi_{0}\rho$. Due to some previous investigations that have explored to describe the behavior of the universe with a negative CC, we extend our analysis to this case. We found that future singularities like Big-Rip are allowed but without having a phantom EoS associated to the DE fluid. Big-Crunch singularities also appears when a negative CC is present, but also de Sitter and even Big-Rip types are allowed due to the negative pressure of the viscosity, which opens the possibility of an accelerated expansion in AdS cosmologies. We also discuss a very particular solution without Big Bang singularity that arises in the early-time radiation dominant era of our model known as Soft-Big Bang.

Comment: 17 pages, 13 figures

Subjects by Vocabulary

arXiv: Physics::Fluid Dynamics


General Relativity and Quantum Cosmology

Related Organizations
95 references, page 1 of 10

[1] Adam G. Riess et. al. Observational evidence from supernovae for an accelerating universe and a cosmological constant. The Astronomical Journal, Volume 116, Issue 3, pp. 1009-1038,(1998), .

[2] S. Perlmutter et. al. Measurements of and from 42 High-Redshift Supernovae. Astrophys.J.517:565-586,1999, .

[3] N. Aghanim et. al. Planck 2018 results. vi. cosmological parameters. A&A 641, A6 (2020), .

[4] Joseph Ryan Shulei Cao and Bharat Ratra. Using pantheon and des supernova, baryon acoustic oscillation, and hubble parameter data to constrain the hubble constant, dark energy dynamics, and spatial curvature. MNRAS, 504, 300-310 (2021). [OpenAIRE]

[5] Shadab Alam et. al. The clustering of galaxies in the completed sdss-iii baryon oscillationspectroscopic survey: cosmological analysis of the dr12 galaxy sample. Mon.Not.Roy.Astron.Soc. 470 (2017) 3, 2617-2652, . [OpenAIRE]

[6] M. Tegmark et. al. Cosmological parameters from SDSS and WMAP. Phys.Rev.D69:103501,2004, .

[7] G. Hinshaw et. al. Nine-year wilkinson microwave anisotropy probe (wmap) observations: Cosmological parameter results. Astrophys.J.Suppl. 208 (2013) 19, .

[8] Martiros Khurshudyan. On the phenomenology of an accelerated large-scale universe. Symmetry 8 (2016) 12, 110. [OpenAIRE]

[9] Varun Sahni. Dark matter and dark energy. Lect.NotesPhys.653:141-180,2004. [OpenAIRE]

[10] Shin'ichi Nojiri Sergei D. Odintsov Kazuharu Bamba, Salvatore Capozziello. Dark energy cosmology: the equivalent description via di erent theoretical models and cosmography tests. Astrophysics and Space Science (2012) 342:155-228.