Testing the Sensitivity of the Galactic Center Excess to the Point Source Mask

Explaining the GeV Antiproton Excess, GeV γ-Ray Excess, and W-Boson Mass Anomaly in an Inert Two Higgs Doublet Model

For the newly discovered W-boson mass anomaly, one of the simplest dark matter (DM) models that can account for the anomaly without violating other astrophysical and experimental constraints is the inert two Higgs doublet model, in which the DM mass (m_{S}) is found to be within ∼54-74  GeV. In this model, the annihilation of DM via SS→bb[over ¯] and SS→WW^{*} would produce antiprotons and gamma rays, and may account for the excesses identified previously in both particles. Motivated by this, we reanalyze the AMS-02 antiproton and Fermi-LAT Galactic center γ-ray data. For the antiproton analysis, the novel treatment is the inclusion of the charge-sign-dependent three-dimensional solar modulation model as constrained by the time-dependent proton data. We find that the excess of antiprotons is more distinct than previous results based on the force-field solar modulation model. The interpretation of this excess as the annihilation of SS→WW^{*} (SS→bb[over ¯]) requires a DM mass of ∼40-80 (40-60) GeV and a velocity-averaged cross section of O(10^{-26})  cm^{3} s^{-1}. As for the γ-ray data analysis, besides adopting the widely used spatial template fitting, we employ an orthogonal approach with a data-driven spectral template analysis. The fitting to the GeV γ-ray excess yields DM model parameters overlapped with those to fit the antiproton excess via the WW^{*} channel. The consistency of the DM particle properties required to account for the W-boson mass anomaly, the GeV antiproton excess, and the GeV γ-ray excess suggests a common origin of them.

Dissecting the Inner Galaxy with γ-Ray Pixel Count Statistics

We combine adaptive template fitting and pixel count statistics in order to assess the nature of the Galactic Center excess in Fermi-LAT data. We reconstruct the flux distribution of point sources well below the Fermi-LAT detection threshold, and measure their radial and longitudinal profiles in the inner Galaxy. We find that all point sources and the bulge-correlated diffuse emission each contributes O(10%) of the total inner Galaxy emission, and disclose a potential subthreshold point-source contribution to the Galactic Center excess.

Galactic Center Excess in a New Light: Disentangling the γ-Ray Sky with Bayesian Graph Convolutional Neural Networks

A fundamental question regarding the Galactic Center excess (GCE) is whether the underlying structure is pointlike or smooth, often framed in terms of a millisecond pulsar or annihilating dark matter (DM) origin for the emission. We show that Bayesian neural networks (NNs) have the potential to resolve this debate. In simulated data, the method is able to predict the flux fractions from inner Galaxy emission components to on average ∼0.5%. When applied to the Fermi photon-count map, the NN identifies a smooth GCE in the data, suggestive of the presence of DM, with the estimates for the background templates being consistent with existing results.

Status, Challenges and Directions in Indirect Dark Matter Searches

Indirect searches for dark matter are based on detecting an anomalous flux of photons, neutrinos or cosmic-rays produced in annihilations or decays of dark matter candidates gravitationally accumulated in heavy cosmological objects, like galaxies, the Sun or the Earth. Additionally, evidence for dark matter that can also be understood as indirect can be obtained from early universe probes, like fluctuations of the cosmic microwave background temperature, the primordial abundance of light elements or the Hydrogen 21-cm line. The techniques needed to detect these different signatures require very different types of detectors: Air shower arrays, gamma- and X-ray telescopes, neutrino telescopes, radio telescopes or particle detectors in balloons or satellites. While many of these detectors were not originally intended to search for dark matter, they have proven to be unique complementary tools for direct search efforts. In this review we summarize the current status of indirect searches for dark matter, mentioning also the challenges and limitations that these techniques encounter.

Spurious Point Source Signals in the Galactic Center Excess

We reexamine evidence that the Galactic Center Excess (GCE) originates primarily from point sources (PSs). We show that in our region of interest, non-Poissonian template fitting evidence for GCE PSs is an artifact of unmodeled north-south asymmetry of the GCE. This asymmetry is strongly favored by the fit (although it is unclear if this is physical), and when it is allowed, the preference for PSs becomes insignificant. We reproduce this behavior in simulations, including detailed properties of the spurious PS population. We conclude that the non-Poissonian template fitting evidence for GCE PSs is highly susceptible to certain systematic errors and should not at present be taken to robustly disfavor a dominantly smooth GCE.