We study the impact of astrophysical processes on the gamma-ray background produced by the annihilation of dark matter particles in cosmological halos, with particular attention to the consequences of the formation of supermassive black holes. In scenarios where these objects form adiabatically from the accretion of matter on small seeds, dark matter is first compressed into very dense “spikes”, then its density progressively decreases due to annihilations and scattering off of stellar cusps. With respect to previous analyses, based on non-evolving halos, the predicted annihilation signal is higher and significantly distorted at low energies, reflecting the large contribution to the total flux from unevolved spikes at high redshifts. The peculiar spectral feature arising from the specific redshift distribution of the signal, would discriminate the proposed scenario from more conventional astrophysical explanations. We discuss how this affects the prospects for detection and demonstrate that the gamma-ray background from DM annihilations might be detectable even in absence of a signal from the Galactic center.

Publication Date



This is the pre-print of an article published by the American Physical Society. The final, published version is available here: https://doi.org/10.1103/PhysRevD.76.023517

© 2007 American Physical Society

Also archived in: arXiv:astro-ph/0703236 v2 Jul 31 2007

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus