# Stars in EMMA

The apparition of the first stars radically changed the state of the gas in the Univers. With their highly energetic radiation, they heat up and ionize the surrounding gas. Moreover, at the end of their life, stars explode in supernovae, which create swirl in the gas around them. But this gas is also the main material use to grow the next generation of stars, and a change in his state could have consequence on the star formation rate (hereafter SFR) of the futures generations. To study this period of intense change, induced by a complex coupling into different physics, we need to use numerical simulations.

I’m working with EMMA (Aubert 2015), an AMR cosmological code with fully coupled radiative hydrodynamics, in which one I’ve implement a star formation recipe and different types of supernovae feedback.

A goal of this work is to study the influence of feedback on halo. Specially, I’m trying to quantify the change in the SFR for different class of halo mass. Has seen in the CODA simulation (Ocvirk 2015), I’m expecting a diminution of the instantaneous SFR in the less massive halo ($$M<10^9M_{\odot}$$).

I also see that the way energy is injected had a real impact on the results. I’ll show that the choice of supernovae model is crucial, and the response of the simulation can drastically change, while the total energy injected in conserved.

Furthermore I observe a dependency of the stellar mass resolution on how the reionization occur while the total number of emitted photons is conserved.

### References

1. Dominique Aubert, Nicolas Deparis, Pierre Ocvirk. EMMA: an AMR cosmological simulation code with radiative transfer. arXiv:1508.07888 [astro-ph] (2015). Link

2. Pierre Ocvirk, Nicolas Gillet, Paul R. Shapiro, Dominique Aubert, Ilian T. Iliev, Romain Teyssier, Gustavo Yepes, Jun-Hwan Choi, David Sullivan, Alexander Knebe, Stefan Gottloeber, Anson D’Aloisio, Hyunbae Park, Yehuda Hoffman, Timothy Stranex. Cosmic Dawn (CoDa): the First Radiation-Hydrodynamics Simulation of Reionization and Galaxy Formation in the Local Universe. ArXiv e-prints 1511, 11 (2015). Link