## Constraining Dark Energy from Local Universe

#### by Dr. David Benisty

*Frankfurt Institute for Advanced Studies*

##### at Astrophysics and Cosmology Seminar

Wed, 28 Feb 2024, 11:10

Sacta-Rashi Building for Physics (54), room 207

#### Abstract

In this talk I will develop a method to constrain the Cosmological Constant Λ from binary galaxies, focusing on the Milky Way and Andromeda. I will provide an analytical solution to the two-body problem with Λ and show that the ratio between the Keplerian period and TΛ = 2π/(c √ Λ) ≈ 63.2 Gyr controls the importance of effects from the Cosmological Constant. The Andromeda-Milky Way orbit has a period of ∼ 20 Gyr and so Dark Energy has to be taken into account. Using the current best mass estimates of the Milky Way and Andromeda galaxies, I find the Cosmological Constant value based only on the Local Group dynamics to be lower than 5.44 times the value obtained by Planck. With future astrometric measurements, the bound on the Cosmological Constant can be reduced to (1.67 ± 0.79) ΛPL. The results offer the prospects of constraints on Λ over very different scales than previously. With other binary systems I show that the upper bound on the cosmological constant decreases when the orbital period of the system increases, emphasizing that Λ is a critical period in binary motion

Created on 23-02-2024 by Zitrin, Adi (zitrin)

Updaded on 23-02-2024 by Zitrin, Adi (zitrin)