Detection of a Gamma-Ray Source in the Galactic Center Consistent with Extended Emission from Dark Matter Annihilation and Concentrated Astrophysical Emission (1207.6047v4)

Abstract: We show the existence of a statistically significant, robust detection of a gamma-ray source in the Milky Way Galactic Center that is consistent with a spatially extended signal using about 4 years of Fermi-LAT data. The gamma-ray flux is consistent with annihilation of dark matter particles with a thermal annihilation cross-section if the spatial distribution of dark matter particles is similar to the predictions of dark matter only simulations. We find statistically significant detections of an extended source with gamma-ray spectrum that is consistent with dark matter particle masses of approximately 10 GeV to 1 TeV annihilating to b/b-bar quarks, and masses approximately 10 GeV to 30 GeV annihilating to tau+ tau- leptons. However, a part of the allowed region in this interpretation is in conflict with constraints from Fermi observations of the Milky Way satellites. The biggest improvement over the fit including just the point sources is obtained for a 30 GeV dark matter particle annihilating to b/b-bar quarks. The gamma-ray intensity and spectrum are also well fit with emission from a millisecond pulsar (MSP) population following a density profile like that of low-mass X-ray binaries observed in M31. The greatest goodness-of-fit of the extended emission is with spectra consistent with known astrophysical sources like MSPs in globular clusters or cosmic ray bremsstrahlung on molecular gas. Therefore, we conclude that the bulk of the emission is likely from an unresolved or spatially extended astrophysical source. However, the interesting possibility of all or part of the extended emission being from dark matter annihilation cannot be excluded at present.

• The paper presents a robust detection of extended gamma-ray emission consistent with dark matter annihilation signals in the Galactic Center.
• It employs four years of Fermi-LAT data with binned likelihood analysis to test spatial models and annihilation channels, including those producing b-quark and tau-lepton pairs.
• The findings support further observational studies with improved resolution to differentiate dark matter signals from astrophysical sources such as unresolved millisecond pulsars.

Analysis of Gamma-Ray Sources in the Galactic Center and Implications for Dark Matter

The paper "Detection of a Gamma-Ray Source in the Galactic Center Consistent with Extended Emission from Dark Matter Annihilation and Concentrated Astrophysical Emission" by Abazajian and Kaplinghat presents an in-depth analysis of gamma-ray emissions observed at the Galactic Center using data from the Fermi Large Area Telescope (LAT). The researchers operate under the assumption that these emissions could potentially offer significant insights into the nature of dark matter or astrophysical phenomena like unresolved millisecond pulsars (MSPs). The intricate details and methodologies outlined in the paper extend our understanding of high-energy astrophysical processes and galactic dynamics.

Overview of Methodology

The authors employ approximately four years of Fermi-LAT data, focusing their analysis on the gamma-ray emissions extending up to 100 GeV. They assess multiple spatial emission profiles, such as spherical $\alpha\beta\gamma$ profiles, and consider annihilation channels involving both quarks and leptons to fit the observed spectra. The authors perform binned likelihood evaluations to discern the presence of consistent and statistically significant extended emissions.

Key Findings

• Statistical Significance: The extended gamma-ray source is detected at a statistically robust level, consistent with dark matter particle annihilation considering the thermal cross-section.
• Emission Interpretation: A range of potential explanations for the emissions is explored. While the findings align with the expected signal from WIMP annihilation into $b\bar b$ quarks or $\tau^+\tau^-$ leptons, the emissions are also consistent with an unresolved MSP population or cosmic ray interactions with molecular gas.
• Flux Estimates: The gamma-ray flux in the region is best fit with 30 GeV dark matter particles annihilating to $b\bar b$ quarks and is statistically significant over background models.

Theoretical and Practical Implications

The theoretical implications are notable, particularly in supporting a dark matter component consistent with canonical WIMP models while maintaining compatibility with constraints from observational data for Milky Way satellites. Practically, the identification of gamma-ray signatures of this kind enunciates the complexity of galactic center environments and the need for detailed astrophysical source catalogs.

The results highlight the potential presence of a dark matter signature within the Galactic Center, with parameters that reside near the edge of existing constraints from astrophysical observations and theoretical frameworks. This suggests further targeted observations and refined models may be critical for either confirming or refuting the presence of dark matter signals in such regions.

Future Prospects

Future developments in understanding this gamma-ray source will likely stem from improved observations and extended data collection by space-based telescopes. By resolving spectral degeneracy and enhancing spatial resolution, upcoming missions could significantly narrow down the interpretations. Additionally, cross-referencing with other cosmic phenomena, particularly at differential spatial scales or energy ranges, may refine our interpretation of these findings.

In conclusion, Abazajian and Kaplinghat provide compelling evidence for extended gamma-ray emission at the Galactic Center, laying the groundwork for future explorations in both dark matter physics and high-energy astrophysics. Their work underscores the importance of multi-faceted analytic approaches to disentangle the complex interactions in such dense and energetic galactic regions.