A different interpretation of GRB spectra: backscattering model to explain keV-MeV and proton-synchrotron for TeV emission

In this talk, I will present two recent models for explaining the observed GRB spectra. As a GRB jet drills its way through the collapsing star, it traps a baryonic “cork” ahead of it. If the jet does not cross this cork, but rather photons that are emitted deep in the flow (e.g., by pair annihilation) are scattered by the cork, an observer close to the jet axis will see these photons due to light abberation. I will show that this model has several advantages, such s its ability to naturally explain both the high and low energy spectral slopes, the observed temporal peak evolution, the delay of the soft photons and the E_pk-Eiso (”Amati”) relation, among others. The Euclid mission: current status, results from early observations, and future prospects / 627 Unveiling the darkness: Cosmology Through Euclid satellite The current standard model of cosmology successfully describes a variety of measurements, but the nature of its main components, dark matter and dark energy, remains unknown. The Euclid mission will provide high-resolution optical imaging, along with near-infrared imaging and spectroscopy, covering approximately 14,000 square degrees of extragalactic sky. Euclid is optimized for two powerful and complementary probes: weak gravitational lensing and galaxy clustering. These are among the most sensitive tools for investigating dark energy and gravity on cosmological scales. One of Euclid’s primary goals is to constrain the dark energy equation of state, aiming for a figure of merit (FoM) greater than 400. Additionally, it seeks to measure the growth-index factor with a 1-sigma uncertainty of 0.02. The high-quality data from Euclid will also address the Hubble constant (H0) debate, as its primary probes will provide state-of-the-art constraints on the cosmological parameters of the baseline flat ΛCDM model, significantly reducing uncertainties on all these parameters. Euclid will also enhance our ability to test extensions of the standard cosmological model, such as improving constraints on the sum of neutrino masses. In this talk, I will highlight Euclid’s key cosmological science cases and discuss the benefits of cross-correlating Euclid data with CMB observations to tighten parameter constraints and minimize systematic effects.