Eppur non si trovano: Comments on the Primordial Black Hole Limits in the Galactic Halo

TL;DR

This paper defends the validity of long-term microlensing surveys, reaffirming that primordial black holes and similar objects remain undetected in the Milky Way halo, despite extensive observational efforts.

Contribution

It clarifies misconceptions about previous microlensing results and confirms that primordial black holes are still not observed as dark matter candidates in the Galactic halo.

Findings

Microlensing surveys have not detected primordial black holes in the Milky Way halo.

Previous critiques of microlensing results are scientifically unfounded.

Primordial black holes remain a viable dark matter candidate due to lack of detection.

Abstract

In a recent arXiv post, Hawkins & Garcia-Bellido raised doubts on the results of 20-yr long OGLE photometric monitoring, which did not find a large number of gravitational microlensing events in the direction of the Magellanic Clouds. These results implied that primordial black holes and other compact objects with masses from 10^{-8} to 10^3 M_solar cannot comprise a substantial fraction of the Milky Way dark matter halo. Unfortunately, the Hawkins & Garcia-Bellido post contained a number of scientific misrepresentations of our work. Here, we demonstrate that their arguments lack a solid basis or are simply incorrect. As we show below, "and yet they are not found" - compact objects (including primordial black holes) in the dark halo of the Milky Way remain undetected, despite extensive searches.