The Scoured Spike: Suppression of Indirect Dark Matter Signals by a Hidden Companion
Jaden Lopez, Stefano Profumo

TL;DR
This paper investigates how a hidden massive companion near the Galactic Center can dynamically reduce dark matter density spikes, significantly suppressing expected annihilation signals depending on the companion's properties and the spike profile.
Contribution
It provides a quantitative model for the suppression of dark matter annihilation signals caused by a massive orbiting companion, incorporating analytic and numerical methods.
Findings
Suppression of the J-factor can reach one to two orders of magnitude.
Steeper spikes are less affected unless the companion is massive or long-lived.
A simple fitting formula accurately captures the suppression effect.
Abstract
A massive ``dark companion'' -- such as an intermediate-mass black hole or other compact dark object -- orbiting the supermassive black hole at the Galactic Center can dynamically reshape the surrounding dark-matter spike. Through gravitational heating and angular-momentum exchange, the companion excavates a ``scoured'' region that lowers the inner density and suppresses the expected annihilation signal. We quantify this effect by computing the suppression of the dark-matter annihilation -factor induced by such a companion, combining an analytic scouring-radius model with full numerical integrations of the modified density profile. We scan the parameter space of companion mass, orbital separation, system age, and spike slope, explicitly including the interplay with the annihilation plateau. \textcolor{black}{For canonical Gondolo--Silk spikes with , the…
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Taxonomy
TopicsDark Matter and Cosmic Phenomena · Astrophysical Phenomena and Observations · Pulsars and Gravitational Waves Research
