Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-08-22
Mon.Not.Roy.Astron.Soc.382:621,2007
Astronomy and Astrophysics
Astrophysics
23 pages, 11 figures, 2 tables. Reference added. Mon. Not. Roy. Astro. Soc in print
Scientific paper
10.1111/j.1365-2966.2007.12383.x
We explore the effects of a positive cosmological constant on astrophysical and cosmological configurations described by a polytropic equation of state. We derive the conditions for equilibrium and stability of such configurations and consider some astrophysical examples where our analysis may be relevant. We show that in the presence of the cosmological constant the isothermal sphere is not a viable astrophysical model since the density in this model does not go asymptotically to zero. The cosmological constant implies that, for polytropic index smaller than five, the central density has to exceed a certain minimal value in terms of the vacuum density in order to guarantee the existence of a finite size object. We examine such configurations together with effects of $\Lambda$ in other exotic possibilities, such as neutrino and boson stars, and we compare our results to N-body simulations. The astrophysical properties and configurations found in this article are specific features resulting from the existence of a dark energy component. Hence, if found in nature would be an independent probe of a cosmological constant, complementary to other observations.
Balaguera-Antolinez Andres
Mota David F.
Nowakowski Marek
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