Gaia's faintest stars

TL;DR

This paper reports a search for primordial black holes in the Gaia archive, which was unsuccessful, and discusses future prospects with microlensing using the Rubin telescope to detect these elusive objects.

Contribution

It presents the first search for primordial black holes in Gaia data and highlights the potential of microlensing with the Rubin telescope for future detection.

Findings

No primordial black holes detected in Gaia data

Microlensing with Rubin telescope could be promising for future searches

Highlights the importance of technological advances in black hole detection

Abstract

In the Brief History of Time Stephen Hawking was pessimistic about astronomers detecting primordial black holes (PBHs). He would not be the only distinguished scientist to underestimate the extraordinary power of new technology. In a related area Albert Einstein published the equations for microlensing, but wrote off their practicality. Perhaps they meant "during my lifetime." The amazing properties of PBHs, however, validate heroic efforts to detect them. If they exist, their niches in our current history of time include supplying dark matter to bind galaxies, offering a solution for the Hubble tension, and, as supermassive black holes, giving us quasars as far as the eye can see. This Research Note describes a search for PBHs in the Gaia archive. In spite of the high density of local dark matter, it was unsuccessful. Microlensing with the Rubin telescope is the tool at our disposal to open the asteroid window for PBH.