Hunting Dark Matter in ultra-compact structures within the Milky-Way

TL;DR

This paper explores the potential existence and detection of ultra-compact mini-halos made of dark matter in the Milky Way, which could inform early universe physics and impact planetary environments.

Contribution

It proposes a multi-frequency search strategy for UCMHs in the Milky Way using Gaia data, linking microlensing to dark matter detection and planetary impact hypotheses.

Findings

UCMHs could serve as probes of early universe physics.

Detection strategies can identify UCMHs via microlensing and emissions.

Encounters with UCMHs might influence planetary magnetic fields.

Abstract

The local environment is ideal for searching out compact dark structures via the microlensing and multi-frequency emissions as these objects are expected to be faint and microlensing experiments have already hinted at their possibility. In the case that these objects are composed of Dark Matter (DM) then there are both few limits on their abundance but many consequences of their existence or non-existence on both local and cosmic scales. In this work we examine the possibility of Ultra-Compact Mini-Halos (UCMHs) formed in the early universe. These objects can persist to the present epoch due to their large central density inuring them to the worst effects of later tidal stripping. As such, these objects could constitute probes of many details of early universe physics, such as primordial phase-transitions, inflation, small scale exploration of the primordial density perturbation field and non-Gaussianity of these density perturbations. The fact that they are also highly dark matter-dominated objects means that they are attractive objects of study in the continuing hunt for the nature of Dark Matter (DM) through indirect detection. Another reason to study such objects in the local environment is found in the conjecture that encounters with UCMHs could induce catastrophic events on planets within our solar system, e.g. mass-extinction events on Earth. We will outline a strategy for multi-frequency UCMH searches within the region of the Milky-Way in which Gaia can accurately reconstruct microlens masses. This methodology ensures that any candidate UCMH DM emission should correlate to some unidentified microlensing object with determinable mass and demonstrate that large-scale volcanic extinctions on Earth due to UCMHs are unlikely but that it is possible for loss of the Martian geodynamo to be driven encounters with such compact objects.