Cross-correlation of weak lensing and gamma rays: Implications for the nature of dark matter

Tilman Tröster, Stefano Camera, Mattia Fornasa, Marco Regis, Ludovic Van Waerbeke, Joachim Harnois-Déraps, Shin'ichiro Ando, Maciej Bilicki, Thomas Erben, Nicolao Fornengo, Catherine Heymans, Hendrik Hildebrandt, Henk Hoekstra, Konrad Kuijken, Massimo Viola

    Research output: Contribution to journalArticlepeer-review


    We measure the cross-correlation between Fermi gamma-ray photons and over 1000 deg2 of weak lensing data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), the Red Cluster Sequence Lensing Survey (RCSLenS), and the Kilo Degree Survey (KiDS). We present the first measurement of tomographic weak lensing cross-correlations and the first application of spectral binning to cross-correlations between gamma rays and weak lensing. The measurements are performed using an angular power spectrum estimator while the covariance is estimated using an analytical prescription. We verify the accuracy of our covariance estimate by comparing it to two internal covariance estimators. Based on the nondetection of a cross-correlation signal, we derive constraints on weakly interacting massive particle (WIMP) dark matter. We compute exclusion limits on the dark matter annihilation cross-section 〈σann v〉, decay rate Γ dec and particle mass mDM. We find that in the absence of a cross-correlation signal, tomography does not significantly improve the constraining power of the analysis. Assuming a strong contribution to the gamma-ray flux due to small-scale clustering of dark matter and accounting for known astrophysical sources of gamma rays, we exclude the thermal relic cross-section for particle masses of mDM ≲ 20 GeV.

    Original languageEnglish
    Pages (from-to)2706-2722
    Number of pages17
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number3
    Early online date11 Feb 2017
    Publication statusPublished - Jun 2017


    • Dark matter
    • Gamma-rays: Diffuse background
    • Gravitational lensing: Weak


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