Background model systematics for the Fermi GeV excess
read the original abstract
The possible gamma-ray excess in the inner Galaxy and the Galactic center (GC) suggested by Fermi-LAT observations has triggered a large number of studies. It has been interpreted as a variety of different phenomena such as a signal from WIMP dark matter annihilation, gamma-ray emission from a population of millisecond pulsars, or emission from cosmic rays injected in a sequence of burst-like events or continuously at the GC. We present the first comprehensive study of model systematics coming from the Galactic diffuse emission in the inner part of our Galaxy and their impact on the inferred properties of the excess emission at Galactic latitudes $2^\circ<|b|<20^\circ$ and 300 MeV to 500 GeV. We study both theoretical and empirical model systematics, which we deduce from a large range of Galactic diffuse emission models and a principal component analysis of residuals in numerous test regions along the Galactic plane. We show that the hypothesis of an extended spherical excess emission with a uniform energy spectrum is compatible with the Fermi-LAT data in our region of interest at $95\%$ CL. Assuming that this excess is the extended counterpart of the one seen in the inner few degrees of the Galaxy, we derive a lower limit of $10.0^\circ$ ($95\%$ CL) on its extension away from the GC. We show that, in light of the large correlated uncertainties that affect the subtraction of the Galactic diffuse emission in the relevant regions, the energy spectrum of the excess is equally compatible with both a simple broken power-law of break energy $2.1\pm0.2$ GeV, and with spectra predicted by the self-annihilation of dark matter, implying in the case of $\bar{b}b$ final states a dark matter mass of $49^{+6.4}_{-5.4}$ GeV.
This paper has not been read by Pith yet.
Forward citations
Cited by 9 Pith papers
-
WIMP-like Dark Matter Without Thermalization At Freeze-Out
Hidden-sector dark matter achieves standard thermal relic abundance via early decoupling with temperature-matched freeze-out, enabling WIMP-like cross sections without late-time thermalization.
-
Producing the GeV Galactic Center Excess via Cosmic Ray-Dark Matter Scattering
Cosmic ray protons scattering off dark matter produce the Galactic Center gamma-ray excess through inelastic up-scattering followed by decay or direct elastic 2-to-3 photon production.
-
Probing Cosmic-Ray-Boosted and Supernova-Sourced Sub-GeV Dark Matter with Paleo-Detectors
Paleo-detectors can achieve high sensitivity to sub-GeV dark matter boosted by cosmic rays and supernovae, covering previously inaccessible parameter space with orders of magnitude better reach than current experiments.
-
High-dimensional inference for the $\gamma$-ray sky with differentiable programming
A differentiable forward model and likelihood enable probabilistic inference over many spatial morphologies for the Galactic Center gamma-ray Excess using variational methods on GPUs.
-
Strong Constraints on Millisecond Pulsar Injection Spectra from Fermi-LAT Observations of the Galactic Center
Joint prompt and inverse-Compton modeling of MSP-injected e± yields strong upper limits on η_e/η_γ from recent Fermi-LAT GCE spectra that exceed MAGIC globular-cluster bounds.
-
A Precise Measurement of the Fermi-LAT Galactic Center Excess Morphology and Spectrum
Refined Fermi-LAT analysis finds the Galactic Center Excess has a centrally concentrated spherical morphology consistent with generalized Navarro-Frenk-White inner slope ~1.15, significant across interstellar emission...
-
A Precise Measurement of the Fermi-LAT Galactic Center Excess Morphology and Spectrum
An optimized Fermi-LAT analysis finds the Galactic Center Excess follows an approximately spherical generalized NFW morphology with inner slope ~1.15, a spectrum peaking at a few GeV, and only upper limits above tens of GeV.
-
A Comprehensive Study of WIMP Models Explaining the Fermi-LAT Galactic Center Excess
WIMP models for the Galactic Center Excess survive only in finely tuned resonant funnels with portal couplings around 10^-4, with leptophilic vectors and pseudoscalar portals remaining most viable after current bounds.
-
Testing Viability of Benchmark Dark Matter Models for the Galactic Center Excess
Updated constraints on two simplified dark matter models for the Galactic Center Excess leave unconstrained parameter space after applying recent multi-experiment data.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.