Natural quenching of stellar formation

Abstract

Observation shows that, over cosmic history, star formation increased until z = 2. After that it su ered a strong quenching. Various internal and external causes have been postulated to explain this phenomenon. In this paper, we investigate a third more fundamental possibility, which we call \natural quenching". This quenching would simply arise as the consequence of the growth of halos. According to numerical simulations, the more massive halos, the less concentrated they are so that the gas trapped within them cools at a lower rate. Consequently, over cosmic evolution, the accretion of gas onto galaxies slows down, which translates into a lower star formation rate. The aim of this study is to find the characteristic time at which this natural quenching becomes effective and check whether it coincides with a redshift of about 2.