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Age problem in the LCDM model

  1. Mar 12, 2015 #1

    wolram

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    From what i have read, right or wrong, there seems to be an universe (age) problem for modern cosmologists,
    This is the best paper i have found on the subject.

    http://arxiv.org/pdf/1402.6433v3.pdf

    Abstract Many dark energy models fail to pass the cosmic age test. In this paper, we investigate the cosmic age problem associated with nine extremely old Global Clusters (GCs) and the old quasar APM 08279+5255 in the Rh = ct Universe. The age data of these oldest GCs in M31 is acquired from the Beijing-Arizona-TaiwanConnecticut system with up-to-date theoretical synthesis models. They have not been used to test the cosmic age problem in the Rh = ct Universe in previous literature. By evaluating the age of the Rh = ct Universe with the observational constraints from the type Ia supernovae and Hubble parameter, we find that the Rh = ct Universe can accommodate five GCs and the quasar APM 08279+5255 at redshift z = 3.91. But for other models, such as ΛCDM, interacting dark energy model, generalized Chaplygin gas model and holographic dark energy model, can not accommodate all GCs and the quasar APM 08279+5255. It is worthwhile to note that the age estimates of some GCs are controversial. So, unlike other cosmological models, the Rh = ct Universe can marginally solve the cosmic age problem, especially at high redshift

    Are there any other factors that rule this paper out?
     
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  3. Mar 12, 2015 #2

    Chalnoth

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    I honestly am skeptical of this entire approach. The errors on the ages of these sorts of objects are quite large, and riddled with systematic uncertainties. By comparison, the CMB is very clean experimentally, with little possibility of systematic errors distorting the age by too much.

    So in essence they're trying to challenge the result of a clean, clear experiment with low error bars by using very dirty observations riddled with uncertainties that are difficult to account for. Unless there is a really strong discrepancy, there's just no reason to take this kind of claim seriously.
     
  4. Mar 12, 2015 #3

    Garth

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    Yes, but as we have discussed recently here there are now many objects that seem to pose an age problem in the early universe.

    We have been discussing this on these Forums since 2005:
    [/PLAIN] [Broken]
    Is there an Age Problem in the Mainstream Model? (Oct 2005)

    Cosmic age problem ? (Nov 2008)
    Is There An Age Problem In The Early LCDM Model? (Jun 2010)
    Massive galaxy cluster could upend theory of universe evolution, (Dec 2014)
    and An Age Problem (again)? (Jan 2015)


    Each time we have said there wasn't really a problem and subsequent observations at higher red shift would clear up the matter - but the problem has just continued to get worse. So we still wait and see!

    Garth



     
    Last edited by a moderator: May 7, 2017
  5. Mar 12, 2015 #4

    Chalnoth

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    Of course we have, because in a noisy data set rife with systematic uncertainties, you're guaranteed to get a significant number that look either older than our universe, or too old for a particular model of our universe.
     
  6. Mar 12, 2015 #5

    Garth

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    A quasar with BH M ~1.2 × 1010M and has a luminosity of 4.29 ×1014L seen at z=6.30

    and one ULASJ1120+0641 a quasar which hosts a black hole with a mass of 2×109M and has a luminosity of 6.3×1013L at z=7.085.

    From An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
    Not on their own then, and quite difficult to explain.

    Garth
     
  7. Mar 12, 2015 #6

    Chalnoth

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    Right. That's largely a puzzle of supermassive black hole growth rates (which is a difficult thing to model), and potentially of the specific matter power spectrum in the early universe. It's not an age problem.
     
  8. Mar 12, 2015 #7

    Garth

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    Yes, the problem with SMBH growth being that these are right up against their Eddington limits and very bright.

    A dark BH can form by direct collapse into its Schwarzschild radius, but a very luminous accretion disc is limited by radiation pressure and the BH takes time to form.

    If there isn't enough time then you have an age problem.
     
  9. Mar 12, 2015 #8

    Chalnoth

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    As I said, it's a far, far messier physical system than the CMB. Because supermassive black holes are such complex objects (more accurately, the infalling matter is), it's vastly more likely that we're misunderstanding something about those black holes than it is we're misunderstanding the CMB.

    So these types of studies are interesting, and may have an impact on cosmology (if the discrepancy comes, in part, from misunderstanding structure formation). But they do not present an age problem for our universe as a whole.
     
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