Seminar 1: Dipole Cosmology: The Dipole ΛCDM Model
Vahid Forghanipour
Department of Physics, Sharif University of Technology
Seminar 2: Investigating the halo distribution inside cosmic voids in excursion set theory and the dependence of void galaxies on large-scale environment
Zeynab Ashuri
Department of Physics, Sharif University of Technology
Abstract 1: Is our universe actually homogenous and isotropic on large scales? New observation in last two decades cast some shadow of doubts on standard model of cosmology and FLRW paradigm. In this Seminar we discuss and review the recently published article, “Towards A Realistic Dipole Cosmology: The Dipole ΛCDM Model”, by Ehsan Ebrahimian and M. M. Sheikh-Jabbari. the dipole cosmological principle is the idea that the Universe is a maximally Copernican cosmology, compatible with a cosmic flow. It serves as the most symmetric paradigm that generalizes the FLRW ansatz. In this article they assess the possibility of model building within the dipole cosmology paradigm, and discuss the dynamics of expansion rate, anisotropic shear and tilt, in various examples. A key observation is that the cosmic flow (tilt) can grow even while the anisotropy (shear) dies down. Remarkably, this can happen even in an era of late time acceleration.
Abstract 2: Investigating the formation and evolution of large-scale structures, as one of the main observables in cosmology, is of particular importance. Excursion Set Theory is one of the methods of investigating the statistics of halos and web structures of the universe.
In the standard approach, in this theory, we consider the Sharp-K window function to smooth the matter density perturbation field, which causes the paths to proceed a Markovian random walk. As a result, the statistics of the first up-crossing of the critical barrier and the statistics of the halos can be obtained analytically. Similar procedures can be followed to find Halos which reside inside cosmic voids. The aim of this talk will be to review the distribution of structures inside voids, and to analyze the environmental dependence of galaxy luminosity inside the void halos, in the framework of the Excursion Set theory.
یکشنبه 25 تیر 1402، ساعت 9:30
Sunday 16 July 2023 – 9:30 Tehran Time
Hybrid Seminar
دانشکده فیزیک – طبقه 5 – اتاق 512Physics Department – fifth floor – Room 512/
https://vc.sharif.edu/ch/cosmology
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