Publication date: Sep 2011
Abstract:
Using the pseudo-Newtonian (PN) potential reflecting properties of the
Schwarz-schild-de Sitter spacetime, we estimate the influence of the
repulsive cosmological constant Λ ~ 1.3 ×
10-56cm-2 implied by recent cosmological tests
onto the motion of both Small and Large Magellanic Clouds (SMC and LMC)
in the gravitational field of the Milky Way. Considering detailed
modelling of the gravitational field of the Galaxy disc, bulge and cold
dark matter halo, the trajectories of SMC and LMC constructed for the PN
potential with the cosmological constant are confronted to those given
for Λ = 0. In the realistic model of the extended cold dark matter halo
its edge and related total mass are taken at typical values reflecting
recent diversity in the total Galaxy mass estimates. In all cases,
strong influence of the cosmological constant, on 10% level or higher,
has been found for motion of both SMC and LMC. Inside the halo, the
Newtonian part of the PN potential is exact enough, while outside the
halo the PN potential can give relevant relativistic corrections. The
role of the cosmological constant is most conspicuous when binding mass
is estimated for the satellite galaxies. We have found a strong
influence of cosmic repulsion on the total binding mass for both
galaxies. For SMC there is the binding mass MSMCΛ =
0 = 7.07 × 1011M⨀ and MSMCΛ
> 0 = 8.61 × 1011M⨀, while even much
higher increase is found for LMC, where MLMCΛ = 0
= 1.50 × 1012M⨀ and MLMCΛ >
0 = 2.21 × 1012M⨀, putting serious doubts on
the possibility that the LMC is bounded by the Milky Way. However, the
estimates of binding masses are strongly influenced by initial velocity
of SMC and LMC; we took the values inferred for the IAU MW rotation
velocity ~ 220 km/s. Our results indicate very important role of the
cosmic repulsion in the motion of interacting galaxies, clearly
demonstrated in the case of the satellite SMC and LMC galaxies moving in
the field of Milky Way. In some cases, the effect of the cosmic
repulsion can be even comparable to the effects of the dynamical
friction and the Andromeda Galaxy.
Authors:
Stuchlík, Zdeněk; Schee, Jan;