Quasar-microlensing versus star-microlensing evidence of small-planetary-mass objects as the dominant inner-halo galactic dark matter

TL;DR

This paper compares star and quasar microlensing experiments, suggesting that small planetary-mass objects could be the dominant form of inner-halo galactic dark matter, and that current star-microlensing surveys may miss these objects due to sampling issues.

Contribution

It proposes that small planetary-mass objects are the main inner-halo dark matter and explains why star-microlensing may not detect them, reconciling different microlensing results.

Findings

Star microlensing may underestimate small planetary objects due to sampling bias.

Quasar microlensing provides stronger evidence for these objects as dark matter.

Intermittent lognormal distributions affect microlensing detection probabilities.

Abstract

We examine recent results of two kinds of microlensing experiments intended to detect galactic dark matter objects, and we suggest that the lack of short period star-microlensing events observed for stars near the Galaxy does not preclude either the ``rogue planets'' identified from quasar-microlensing by Schild 1996 as the missing-mass of a lens galaxy, or the clumps of such objects predicted by the new Gibson 1996-2000 hydro-gravitational theory as the inner-halo galactic dark matter. We point out that such micro-brown-dwarfs in nonlinear accretional cascades to form stars give intermittent lognormal number density n_p distributions. Hence, star-microlensing searches that focus on a small fraction of the sky and assume a uniform distribution for n_p are subject to undersampling errors. Sparse independent samples give modes smaller than means of the highly skewed lognormal distributions expected. Quasar-microlensing searches with higher optical depths are less affected by intermittency. We attempt to reconcile the results of the star-microlensing and quasar-microlensing studies. We conclude that star microlensing searches cannot exclude and are unlikely to even detect these objects so easily observed by quasar-microlensing and so robustly predicted by the new theory.