Quantifying the impact of baryon-CDM perturbations on halo clustering and baryon fraction

Hasti Khoraminezhad

Scuola Internazionale Superiore di Studi Avanzati (SISSA)

Abstract: Baryons and cold dark matter (CDM) as the two dominant matter components of the Universe did not comove prior to recombination. This leads to differences in the local baryon and CDM densities, the so-called baryon-CDM isocurvature perturbations . These perturbations are usually neglected in the analysis of Large-Scale Structure data but taking them into account might become important in the era of high precision cosmology. In this talk first I will give a brief overview of isocurvature perturbations and how to measure the corresponding galaxy bias parameter . Then I will turn to various numerical tests to validate our simulation setup required for such perturbations. After that, I will present our results of the impact of such perturbations on the dark matter halos distribution through gravity-only 2-fluid simulations. I will concentrate particularly on the baryon fraction in halos as a function of mass and large-scale and also the measurements of cross-power spectrum between the halo field and  over a wide range of mass which is non-zero and negative showing that halo formation is impacted by . I will demonstrate the agreement between our measurements of the associated bias parameter  through 2-fluid simulations and the so-called separate Universe technique for only-CDM simulations. Finally, I will present the impact of these perturbations on halo-halo power spectrum and the fact that they could be degenerate with the effect of massive neutrinos for high redshift DESI-like surveys.

یکشنبه 23 آذر 1399، ساعت 19:00

Sunday 13 December 2020 – 19:00 Tehran Time

اتاق سمینار مجازی –Virtual Seminar Room

https://vc.sharif.edu/ch/cosmology

گزینه ورود به صورت مهمان – Enter as a Guest