TY - JOUR
T1 - Stable relativistic polytropic objects with cosmological constant
AU - Arbañil, José D.V.
AU - Moraes, Pedro H.R.S.
N1 - Publisher Copyright:
© 2020, Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2020/4/1
Y1 - 2020/4/1
N2 - The effects of the cosmological constant on the static equilibrium configurations and stability against small radial perturbations of relativistic polytropic spheres are investigated. This study numerically solves the hydrostatic equilibrium equation and the radial stability equation, both of which are modified from their standard form to introduce the cosmological constant. For the fluid, we consider a pressure p and an energy density ρ, which are connected through the equation of state p= κδΓ with δ= ρ- p/ (Γ- 1) , where κ, Γ and δ represent the polytropic constant, adiabatic index and rest mass density of the fluid, respectively. The dependencies of the mass, radius and eigenfrequency of oscillations on both the cosmological constant and the adiabatic index are analyzed. For ranges of both the central rest mass density δc and the adiabatic index Γ, we show that the stars have a larger (lower) mass and radius and a diminished (enhanced) stability when the cosmological constant Λ> 0 (Λ< 0) is increased (decreased). In addition, in a sequence of compact objects with fixed Γ and Λ, the regions constructed by stable and unstable static equilibrium configurations are recognized by the conditions d M/ d δc> 0 and d M/ d δc< 0 , respectively.
AB - The effects of the cosmological constant on the static equilibrium configurations and stability against small radial perturbations of relativistic polytropic spheres are investigated. This study numerically solves the hydrostatic equilibrium equation and the radial stability equation, both of which are modified from their standard form to introduce the cosmological constant. For the fluid, we consider a pressure p and an energy density ρ, which are connected through the equation of state p= κδΓ with δ= ρ- p/ (Γ- 1) , where κ, Γ and δ represent the polytropic constant, adiabatic index and rest mass density of the fluid, respectively. The dependencies of the mass, radius and eigenfrequency of oscillations on both the cosmological constant and the adiabatic index are analyzed. For ranges of both the central rest mass density δc and the adiabatic index Γ, we show that the stars have a larger (lower) mass and radius and a diminished (enhanced) stability when the cosmological constant Λ> 0 (Λ< 0) is increased (decreased). In addition, in a sequence of compact objects with fixed Γ and Λ, the regions constructed by stable and unstable static equilibrium configurations are recognized by the conditions d M/ d δc> 0 and d M/ d δc< 0 , respectively.
UR - http://www.scopus.com/inward/record.url?scp=85083498864&partnerID=8YFLogxK
U2 - 10.1140/epjp/s13360-020-00368-x
DO - 10.1140/epjp/s13360-020-00368-x
M3 - Artículo
AN - SCOPUS:85083498864
SN - 2190-5444
VL - 135
JO - European Physical Journal Plus
JF - European Physical Journal Plus
IS - 4
M1 - 354
ER -