Speaker
Description
Dark matter is proposed to dominate the mass-energy content of the Universe, and its nature can be studied via large-scale structure probes, such as the unresolved gamma-ray background (UGRB) using cosmological methods. We investigate the cross-correlation between energy-binned intensity maps of the UGRB from 15 years of Fermi-LAT data and tomographic weak gravitational lensing data from the fourth data release of the Kilo Degree Survey (KiDS-DR4), covering 1006 square degrees. The measurements are performed using the angular power spectrum, and the covariance is calculated using a weighted jackknife estimation. Based on the non-detection of a cross-correlation signal, we derive upper limit constraints on the decay rate $\Gamma_{\rm dec}$ and velocity-averaged annihilation cross-section $\left<\sigma_{\rm ann} v\right>$ of weakly interacting massive particle (WIMP) dark matter as a function of mass. We present the 95 \% upper bounds on the WIMP decay rate and annihilation cross-section and compare them with previous results from other cosmological tracers and local structure observations. Our study provides significant complementary constraints, particularly for low-mass ($ \rm GeV/TeV$) dark matter. The forecast for the 95\% upper bounds from an \textit{Euclid}-like survey cross-correlated with Fermi-LAT indicates that the constraints could be an order of magnitude stronger, showing the potential of future surveys to further constrain dark matter properties.
