Dynamical Effects of Cosmological Constant Antigravity

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Dynamical Effects of Cosmological Constant
Antigravity

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http//leandros.chem.demokritos.gr
WWW Site of Talk http//leandros.chem.demokritos
.gr/cosm-const/index.html astro-ph/0004080
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Contents
1. What is the Cosmological Constant? How
is Gravity Modified? 2. Universe Dynamics,
Bounds from Supernovae. 3. Effects on Other
Metrics Schwarzchild - de Sitter Metric
4. Newtonian Limit Gravity vs Antigravity 5.
Dynamical Effects on Astrophysical Scales (Solar
System, Galaxy, Local Group) 6. Conclusion
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What is the Cosmological Constant
The Cosmological Constant is a form of
energy inherent in empty space remaining constant
as the Universe expands.
The only effects of this energy are on gravity.
Einstein Equations
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Effects on FRW Metric
Friedman Equation
Redshifting of energy density
Acceleration
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Bounds on ? from Supernovae
Total Luminocity (Light Curves) Observed Flux
Luminocity Distance
z
0.1
1
Supernovae data
Age constraints
Other data hints
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Schwarzchild - de SitterMetric
Spherically Symmetric Vacuum with non-zero ?
Newtonian Gravitational Interaction
Repulsive term dominates at
Q What are effects of the additional
repulsive term on the various astrophysical
scales ? (solar system, galactic, cluster)
r1 distance in pc, M1 Mass in Solar Masses
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Solar System Scales
Additional Orbit Precession due to ?
Mercury ( )
Predicted Precession
Observ. Resolution
Solar System Tests are not Sensitive to
the presence of the Cosmological Constant
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Galactic Scales
Stable Circular Star Orbit
Calculated Mass Increase due to ?
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Cluster Scales (Local Group)
Local Group approximation Isolated Two Body
System (MW, M31)
Conditions
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Conclusions
1. Dynamical Effects of the Cosmological
Constant Antigravity are not detectable with
present technology on galactic scales and
below. 2. On Cluster Scales (Local Group) and
larger these dynamical effects can be
significant enough to affect the dynamics at
an observable level. 3. Non-dynamical
measurements of galactic masses (eg
gravitational lensing) can be combined with
dynamical estimates on cluster scales and lead
to a direct measurement of the Cosmological
Constant