We investigate the shock acceleration of particles in massive galaxy mergers or collisions, and show that cosmic rays (CRs) can be accelerated up to the second knee energy ~ 0.1-1 EeV and possibly beyond, with a hard spectral index of Γ ≈ 2. Investigating pp interactions of accelerated cosmic rays producing neutrinos and gamma rays up to sub-PeV energies in the respective Isotropic backgrounds
Dark matter remains one of the most enigmatic components of the universe, constituting approximately 27% of its total mass-energy content. Despite its significant gravitational influence on cosmic structures, dark matter's elusive nature has prevented its direct detection. Among the proposed candidates for dark matter, QCD Axions are particularly compelling due to their theoretical origins in the solution to the strong CP problem in quantum chromodynamics.
Axions can form miniclusters in the early universe and which should still be present in our galactic halo. These axion miniclusters can act as gravitational lenses. When a minicluster passes in front of a distant star, it can cause a temporary increase in the star's brightness, known as a microlensing event.
BipoSH (Bipolar Spherical Harmonics) implemented in harmonic space provides a general formalism for quantifying the departure from statistical isotropy for a field on a 2D sphere. The related complementary approach in real space can help ferret out the nature of SI violation signals.
Big Bang Nucleosynthesis (BBN) is the process that formed the lightest elements in the early universe. It occurred within the first few minutes after the Big Bang when the universe was hot and dense enough for nuclear reactions to take place. The primary elements produced during BBN were hydrogen, helium, and small amounts of lithium and beryllium. The relative abundances of these light elements provide important evidence for the Big Bang theory and help constrain cosmological models.
We extend UVS3 to incorporate transient astrophysical phenomena by modelling stochastic flaring events from Galactic M dwarfs. The study of M-dwarf flares, which often peak in UV, provides key insight into stellar magnetism and the radiation environments around potentially habitable exoplanets. Using empirical flare frequency distributions (FFDs) and magnetic activity statistics, we simulate the time-dependent ultraviolet emission from these stars across a range of flare energies and occurrence rates, and analyse their observational photometric signatures.
UVS3 is a general-purpose simulation framework for modeling the ultraviolet (UV) sky as observed by space-based instruments.
It integrates synthesized stellar spectral energy distributions (SEDs), zodiacal light, and Galactic diffuse interstellar radiation field (ISRF)
components to generate realistic UV sky field of view for satellites in low-Earth or geostationary orbits.
GitHub Repository
