Foregrounds in astroparticle physics and cosmology

Effects of physics beyond the standard model of particlephysics and cosmology, are often camouflaged by more conventional astrophysical effects. In this presentation, I will give some examples of this and demonstrate power of novel methods in disentangling different scenarios.  For example, the gamma-ray sky has contributions from astronomical sources like AGNs, star forming galaxies, etc. But there are potentially other  contributions from sources such as particle dark matter. In the light of this, gamma-rays properties of the guaranteed astronomical sources as spectral slope, photon count statistics and polarisation of X-rays and soft gamma-rays is studied in the hope of achieving the broad goal of  understanding the underlying physics of radiative emission of these sources and hopefully disentangling these ``foregrounds'' from other exotic sources such as particle dark matter.