Future Evolution of Nearby Large-Scale Structure in a Universe
Dominated by a Cosmological Constant

Kentaro Nagamine & Abraham Loeb
Harvard-Smithsonian Center for Astrophysics

2003, New Astronomy, 8, 439

[ download paper: postscript (8MB)   PDF(5MB) ]

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We simulate the future evolution of the observed inhomogeneities in the local universe assuming that the global expansion rate is dominated by a cosmological constant. We find that within two Hubble times (~ 30 billion years) from the present epoch, large-scale structures will freeze in comoving coordinates and the mass distribution of bound objects will stop evolving. The Local Group will get somewhat closer to the Virgo cluster in comoving coordinates, but will be pulled away from the Virgo in physical coordinates due to the accelerated expansion of the Universe. In the distant future there will only be one massive galaxy within our event horizon, namely the merger product of the Andromeda and the Milky Way galaxies. All galaxies that are not gravitationally bound to the Local Group will recede away from us and eventually exit from our event horizon. More generally, we identify the critical interior overdensity above which a shell of matter around an object will remain bound to it at late times.
Figures in the Paper: (postscript & PDF files)
Other Figures:  structure snapshots at different times in the future
(t0=present time=13.5 Gyr;  tH=Hubble time=14 Gyr)  (1.8MB postscript & 1MB PDF files) Solid blue cirle = physical radius of 100Mpc/h.
Thick dashed red circle = event horizon at physical 3.6 Gpc/h.
We are grateful to the authors of Mathis et al. (2002) paper and the GIF (German-Israel Foundation) collaboration for allowing us to use their z=0 simulation output as the initial condition of our simulation. In particular, we thank Volker Springel for providing us with the data in a convenient format for the GADGET code, as well as for clearing out some of our technical problems and questions at the initial stage of this work.