Sobre a fração de bárions em aglomerados de galáxias

Abstract

The largest structures known in the universe are clusters of galaxies, which have masses ranging from 10^14-10^15 solar masses. From the chronological point of view, these configurations are relatively recent and would be collapsing gravitationally in a hierarchical process in redshifts smaller than 1.5. In hydrodynamic simulations involving the standard model of cosmology, an important result is that the gas mass fraction (gas mass / total mass) of these structures is constant with redshift. Very recently, some authors using exclusively observational data (without simulations) verified the constancy of the gas fraction (fgas) with the redshift. The mass fraction of the galaxy clusters gas (obtained from X-ray observations) and luminosity distances of type Ia supernovae were used. The galaxy clusters were considered in hydrostatic equilibrium, isothermal and with spherical morphology. In this dissertation, we follow the methodology used in this previous study to investigate whether different hypotheses regarding the morphology and temperature profile of galaxy clusters modify the conclusions about the behavior of the mass fraction of the gas. As a basic result, we found that there were no significant changes in the conclusions.