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Galaxy red shift survey

  1. Feb 7, 2005 #1

    wolram

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    The latest figures for baryonic mass etc.
     
  2. jcsd
  3. Feb 7, 2005 #2

    marcus

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    Hi wolram, I think for some reason you did not get the URL into the post, at least at first.

    I think the URL is
    http://arxiv.org/abs/astro-ph/0501174

    The 2dF Galaxy Redshift Survey: Power-spectrum analysis of the final dataset and cosmological implications
    S. Cole et al., (The 2dFGRS Team)


    "We present a power spectrum analysis of the final 2dF Galaxy Redshift Survey, employing a direct Fourier method. The sample used comprises 221,414 galaxies with measured redshifts. We investigate in detail the modelling of the sample selection. A new angular mask is derived, based on revisions to the photometric calibration. The redshift selection function is determined by dividing the survey according to rest-frame colour, and deducing a self-consistent treatment of k-corrections and evolution for each population. The covariance matrix for the power-spectrum estimates is determined using two different approaches to the construction of mock surveys which are used to demonstrate that the input cosmological model can be correctly recovered. We are confident that the 2dFGRS power spectrum can be used to infer the matter content of the universe. On large scales, our estimated power spectrum shows evidence for the `baryon oscillations' that are predicted in CDM models....
    ... This shift is largely due to the signal from the newly-sampled regions of space, rather than the refinements in the treatment of observational selection. This analysis therefore implies a density significantly below the standard $\Omega_{M} =0.3$: in combination with CMB data from WMAP, we infer $\Omega_{M} =0.231\pm 0.021$."

    stranger and stranger
    It used to be that Dark Energy was 70 percent and Matter (baryonic plus dark) was 30 percent

    now, if I understand the abstract, they want us to believe that Matter is only 23 percent. Maybe i am missing something. i will take more of a look.
    they could be wrong, I guess. Maybe someone who follows this will comment.
     
    Last edited: Feb 7, 2005
  4. Feb 7, 2005 #3

    wolram

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    Sorry Marcus i did post the url, maybe some problem my end.
    This one has me thinking, perish the thought, i think that something
    is going on in the quantum world that we do not know about.
     
  5. Feb 7, 2005 #4

    ohwilleke

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    The bimodal distribution of the data is really striking.
     
  6. Feb 7, 2005 #5

    Chronos

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    The best guess numbers have hovered around 25 - 75 for the past few years:
    http://arxiv.org/abs/astro-ph/0302207
    This flat universe model is composed of 4.4% baryons, 22% dark matter and 73% dark energy
     
  7. Feb 8, 2005 #6

    Garth

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    I could have told you that! [SCC predicts a cold matter density of 22.2% (2/9)]

    Garth
     
    Last edited: Feb 8, 2005
  8. Feb 8, 2005 #7

    wolram

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    By CHRONOS
    This flat universe model is composed of 4.4% baryons, 22% dark matter and 73% dark energy
    --------------------------------------------------------
    I think i read somewhere that if baryonic mass exceeded 4.4% by
    a few percent, then the big bang model would be in trouble, if this
    is so what is the max min baryonic matter allowable in the BB model
     
  9. Feb 8, 2005 #8

    Chronos

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    Start here:
    Primordial Alchemy: From The Big Bang To The Present Universe
    http://arxiv.org/abs/astro-ph/0208186
    Steigman is one of the foremost authorities on BBN.
     
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