Microhalos and Dark Matter Detection

TL;DR

This paper investigates the impact of microhalos and streams on dark matter detection signals, finding that they have minimal effect on direct detection but may slightly enhance indirect detection signals due to surviving dense cores.

Contribution

The study uses numerical simulations to assess the influence of microhalos and streams on dark matter detection, showing their limited impact on direct detection and potential for small enhancements in indirect detection.

Findings

Microhalos and streams do not significantly affect direct detection signals.

Dense central cusps of microhalos survive and slightly boost indirect detection signals.

Dark matter constraints from smooth halo models remain robust.

Abstract

Cosmological structure formation predicts that our galactic halo contains an enormous hierarchy of substructures and streams, the remnants of the merging hierarchy that began with tiny Earth mass microhalos. If these structures persist until the present time, they could influence dramatically the detection signatures of weakly interacting elementary particle dark matter (WIMP). Using numerical simulations that follow the tidal disruption within the Galactic potential and heating from stellar encounters, we find that neither microhalos nor streams have significant impact on direct detection, implying that dark matter constraints derived using simple smooth halo models are relatively robust. We also find that many dense central cusps survive, yielding a small enhancement in the signal for indirect detection experiments.