Short GRBs are produced by relativistic jets arising from binary NS-NS or NS-BH mergers. Since the detection of the first unambiguous off-axis GRB 170817A, we learned that energy distribution in the jet plays an important role in explaining the GRB emission. The structure and dynamics are modified during the first seconds of the jet interaction with a post-merger environment. Conventional studies often assume this environment as a simple homologous and symmetrically expanding wind. However, post-merger outflows exhibit complex dynamics influenced by the accretion disc evolution. Moreover, the r-process nucleosynthesis influences the thermodynamics and properties of the post-merger neutron-rich environment. During the talk, I will show the results of numerical simulations studying the impact of realistic post-merger disc outflow over the jet dynamics at large scales. Our results are substantially different from the typical model with symmetric homologous wind. a) the impact of the r-process on initial wind pressure leads to significant changes in the jet collimation and cocoon expansion; b) the angular structure of thermal and kinetic energy components in the jets, cocoons, and winds differ concerning simple homologous models, hence it would affect the predictions of GRB afterglow emission; c) the temporal evolution of the structure reveals conversion of thermal to kinetic energy being different for each component in the system (jet, cocoon, and wind); d) post-merger environments influence energy structure and material dispersion, altering the interaction between jets and disk winds.

Location: ASU Praha - Spořilov

Spectral energy distribution (SED) can serve as an effective tool in investigating the parameters of the inner region around the central black hole. The study aims to focus on the UV/optical bands in the context of the additional components to the standard active galaxy nuclei (AGNs). We propose a set of scenarios involving the following perturbative elements, namely i) advection driven accretion flow (ADAF) component in the inner region; ii) a secondary black hole component; and iii) a combination of both components. We simulate and comment on the qualitative differences in the UV photometric data and subsequently attempt to retrieve the initial system parameters based on the uncertainties of 2% and 10% in the measured flux, respectively for a given scenario. We also introduce the intrinsic reddening component, as a variation of scenario i) with noticeable similarities to the ADAF component effect, and contemplate their possible disentanglement.

Location: ASU Praha - Spořilov