Elucidating the z-dependence of the MOND acceleration (a_0) within the Scale Invariant Vacuum (SIV) paradigm

Abstract

In a recent paper: ``On the time dependency of $a_0$" the authors claim that they have tested ``one of the predictions of the Scale Invariant Vacuum (SIV) theory on MOND" by studying the dependence of the Modified Newtonian Dynamics (MOND) acceleration at two data sets, low-$z$ ($3.2\times10^{-4}\le z\le 3.2\times10^{-2}$) and high-$z$ ($0.5\le z\le 2.5$). They claim ``both samples show a dependency of $a_0$ from $z$". Here, the work mentioned above is revisited. The explicit analytic expression for the $z$-dependence of the $a_0$ within the SIV theory is given. Furthermore, the first estimates of the $\Omega_m$ within SIV theory give $\Omega_{m}=0.28\pm 0.04$ using the low-z data only, while a value of $\Omega_{m}=0.055$ is obtained using both data sets. This much lower $\Omega_m$ leaves no room for non-baryonic matter! Unlike in the mentioned paper above, the slope in the $z$-dependence of $A_0=\log_{10}(a_0)$ is estimated to be consistent with zero Z-slope for the two data sets. Finally, the statistics of the data are consistent with the SIV predictions; in particular, the possibility of change in the sign of the slopes for the two data sets is explainable within the SIV paradigm; however, the uncertainty in the data is too big for the clear demonstration of a $z$-dependence yet.