Internal kinematics of GAIA eDR3 wide binaries
  Using the recent GAIA eDR3 catalogue we construct a sample of solar
neighbourhood isolated wide binaries satisfying a series of strict
signal-to-noise data cuts, exclusion of random association criteria and
detailed colour-magnitude diagram selections, to minimise the presence of any
kinematic contaminating effects having been discussed in the literature to
date. Our final high-purity sample consists of 423 binary pairs within 130 pc
of the sun and in all cases high-quality GAIA single-stellar fits for both
components of each binary (final average RUWE values of 0.99), both also
restricted to the cleanest region of the main sequence. We find kinematics
fully consistent with Newtonian expectations for separations, $s$, below 0.009
pc, with relative velocities scaling with $\Delta V \propto s^{-1/2}$ and a
total binary mass, $M_{b}$, velocity scaling consistent with $\Delta V \propto
M_{b}^{1/2}$. For the separation region of $s> 0.009$ pc we obtain
significantly different results, with a separation independent $\Delta V
\approx 0.5$ km/s and a $\Delta V \propto M_{b}^{0.24 \pm 0.21}$. This
situation is reminiscent of the low acceleration galactic baryonic Tully-Fisher
phenomenology, and indeed, the change from the two regimes we find closely
corresponds to the $a \lesssim a_{0}$ transition. These results are at odds not
only with Newtonian expectations, but also with MOND predictions, where the
presence of an external field effect implies only small deviations from
Newtonian dynamics are expected for Solar Neighbourhood wide binaries.
