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Thread: No RAR for galaxyclusters

  1. #1
    Join Date
    Mar 2008
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    No RAR for galaxyclusters

    No RAR for galaxyclusters

    Paper: The radial acceleration relation in galaxy clusters
    https://arxiv.org/abs/2001.06141

    The RAR seems to hold at the galaxy level, but this study at the cluster level indicates that the galaxy level RAR is not universal at larger scales.

    The MOND acceleration, a_0 of 1.2 units, which seemed to work for the galactic RAR would appear to need to be replaced with a larger acceleration of 9.5 units.

    One possible way to retain the validity of the RAR is suggest that the RAR is a local Dark Matter effect related to baryons. At larger scales beginning around cluster scales the addition of the cosmological dark matter effect begins to be noticed. As Milgrom noted, MOND does not give an accounting of the cosmological dark matter effect.

    So rather than undermining the veracity of RAR, the study may help to show what range is needed to expose where the cosmological dark matter effect gets noticed.

  2. #2
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    Mar 2008
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    Following closely after the first paper is this similar study of 20 galaxy clusters from CLASH:
    THE RADIAL ACCELERATION RELATION IN CLASH GALAXY CLUSTERS
    https://arxiv.org/abs/2001.08340
    While agreeing with the galaxy scale RAR acceleration of 1.2 units, their cluster scale acceleration is higher than the first study at 20.2 units. It appears again that the galaxy level RAR is not universal at larger scales. It will be of interest to sort out how this cluster acceleration is more that double that of the first paper.

  3. #3
    Join Date
    Mar 2008
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    656
    A somewhat older paper that introduces a factor, z, that multiplies a_0 in the RAR equation with respect to MDM:
    Modified Dark Matter in Galaxies and Galaxy
    Clusters
    https://arxiv.org/abs/1801.00160
    13 galaxy clusters in study

    Today, a paper with a surprising discovery:
    A tight correlation between the enclosed gravitational
    mass and hot gas mass in galaxy clusters at
    intermediate radii
    https://arxiv.org/abs/2001.08863
    64 clusters
    While not about whether there is a universal RAR, it supports that idea that dark matter and baryons correlate.

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