Through a Mini Halo, Darkly

TL;DR

This paper investigates how dense dark matter halos can scatter photons from distant sources, potentially causing observable spectral distortions like the Sunyaev-Zel'dovich effect, which could reveal properties of dark matter structures.

Contribution

It introduces the idea that ultra-compact mini halos can produce detectable photon scattering effects, expanding methods to study dark matter distributions.

Findings

Mini halos can cause observable Comptonisation of AGN spectra.

Dense dark matter clumps can induce a Sunyaev-Zel'dovich effect similar to galaxy clusters.

Estimated encounter rates suggest potential for observational detection.

Abstract

In this Letter we explore the effects of the scattering of photons incident on a dark matter halo through their interaction with either electrons or photons produced by dark matter annihilation. Particularly, we examine the effects of this scattering upon the observed spectrum of a distant AGN or of the Cosmic Microwave Background. Our results indicate that ultra-compact mini halos and other dense dark matter clumps can induce an observable Comptonisation of AGN spectra as well as a Sunyaev-Zel'dovich effect (SZE) with an optical depth similar to that attained by thermal electrons in the Coma cluster. The rate of encounters between a distant AGN and these dense mini-halos is also estimated using micro-lensing limits existing on the population of dark compact bodies.