Intermediate Mass Black Holes and Nearby Dark Matter Point Sources: A Critical Reassessment

TL;DR

This paper critically reassesses the detectability of intermediate mass black holes with dark matter mini-spikes, showing current gamma-ray data already impose strong limits, making future detection prospects unlikely for various cosmic messengers.

Contribution

It provides a detailed statistical analysis demonstrating that existing gamma-ray and cosmic ray data severely constrain the presence of dark matter mini-spikes around intermediate mass black holes.

Findings

EGRET data impose stringent limits on dark matter mini-spikes.

Detection prospects with Fermi/GLAST and Cherenkov telescopes are unlikely.

Cosmic ray and gamma-ray data exclude the possibility that PAMELA/ATIC excesses are due to nearby dark matter sources.

Abstract

The proposal of a galactic population of intermediate mass black holes (IMBHs), forming dark matter (DM) ``mini-spikes'' around them, has received considerable attention in recent years. In fact, leading in some scenarios to large annihilation fluxes in gamma rays, neutrinos and charged cosmic rays, these objects are sometimes quoted as one of the most promising targets for indirect DM searches. In this letter, we apply a detailed statistical analysis to point out that the existing EGRET data already place very stringent limits on those scenarios, making it rather unlikely that any of these objects will be observed with, e.g., the Fermi/GLAST satellite or upcoming Air Cherenkov telescopes. We also demonstrate that prospects for observing signals in neutrinos or charged cosmic rays seem even worse. Finally, we address the question of whether the excess in the cosmic ray positron/electron flux recently reported by PAMELA/ATIC could be due to a nearby DM point source like a DM clump or mini-spike; gamma-ray bounds, as well as the recently released Fermi cosmic ray electron and positron data, again exclude such a possibility for conventional DM candidates, and strongly constrain it for DM purely annihilating into light leptons.