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Integrated Sachs Wolfe Effect - redshifting?

  1. Jan 21, 2015 #1

    ChrisVer

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    Gold Member

    I think this have been discussed a lot, however, here it comes again right in front of me. I'm talking about this article (and also in my class notes):

    http://en.wikipedia.org/wiki/Sachs–Wolfe_effect#Integrated_Sachs.E2.80.93Wolfe_effect

    and in particular at this paragraph:

    So my problem is, how can you talk about an accelerated universe when you look at a supercluster object?
    The accelerated universe makes sense in the FRW metric. However a supercluster (a group of galaxies+clusters that I believe are gravitationally bound -and so the gravitational redshifting of ISW) cannot be described by FRW metric... So how does the well gets "stretched" during the photon's stay in it?
     
  2. jcsd
  3. Jan 21, 2015 #2

    Chalnoth

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    Science Advisor

    A cosmological constant makes it so that gravitationally-bound systems aren't perfectly stable over time. The larger the system is, the more it is impacted. The cosmological constant causes gravitational potential wells and voids to decay over time.
     
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