The Dark Knight Falters
Abstract
Potential line emission at 111 and 129 GeV from 16 unassociated Fermi-LAT point sources has been reported recently by Su & Finkbeiner (2012c). Together with similar features seen by Fermi in a region near the Galactic Centre, the evidence has been interpreted as the spectral signature of dark matter annihilation or internal bremsstrahlung. Through a combination of supervised machine-learning algorithms and archival multiwavelength observations we find that 14 out of the 16 unassociated sources showing the line emission in the Su & Finkbeiner sample are most likely active galactic nuclei (AGN). Based on this new evidence, one must widen the range of possible solutions for the 100-140 GeV excess to include a very distinct astrophysical explanation. While we cannot rule out a dark matter origin for the line emission in the Galactic Centre, we posit that if the detection in the Su & Finkbeiner sample is indeed real it might be related to accretion, bubble, or jet activity in nearby (z < 0.2) AGN. Alternatively, given the right conditions, the similarity could be due to a chance occurrence caused by extragalactic background light (EBL) absorption. Or else one must concede that the features are an artefact of instrumental or calibration issues.
Cite
@article{arxiv.1208.1693,
title = {The Dark Knight Falters},
author = {N. Mirabal},
journal= {arXiv preprint arXiv:1208.1693},
year = {2013}
}
Comments
5 pages, 2 figures, 2 tables, accepted for publication in MNRAS