We analyse the properties of circumgalactic gas around simulated galaxies in the redshift range z ≥ 3, utilizing a new sample of cosmological zoom simulations. These simulations are intended to be representative of the observed samples of Lyman α (Ly α) emitters recently obtained with the multi unit spectroscopic explorer (MUSE) instrument (halo masses ~ 1010- 1011M⊙). We show that supernova feedback has a significant impact on both the inflowing and outflowing circumgalactic medium (CGM) by driving outflows, reducing diffuse inflow rates, and by increasing the neutral fraction of inflowing gas. By temporally stacking simulation outputs, we find that significant net mass exchange occurs between inflowing and outflowing phases: none of the phases are mass-conserving. In particular, we find that the mass in neutral outflowing hydrogen declines exponentially with radius as gas flows outwards from the halo centre. This is likely caused by a combination of both fountain-like cycling processes and gradual photoionization/collisional ionization of outflowing gas. Our simulations do not predict the presence of fast-moving neutral outflows in the CGM. Neutral outflows instead move with modest radial velocities (~ 50 km s-1), and the majority of the kinetic energy is associated with tangential rather than radial motion.
Bibliographical noteFunding Information:
We thank Matthieu Schaller for making data from the no-feedback EAGLE simulation available to us. We are grateful to the LABEX Lyon Institute of Origins (ANR-10-LABX-0066) of the Université de Lyon for its financial support within the programme ‘Investisse-ments d’Avenir’ (ANR-11-IDEX-0007) of the French government operated by the National Research Agency (ANR). Simulations were run at the Common Computing Facility (CCF) of LABEX LIO. JB and JR acknowledge support for the ORAGE project from the Agence Nationale de la Recherche under grant ANR-14-CE33-0016-03. TK acknowledges support by the ERC Advanced Grant 320596 ‘The Emergence of Structure during the Epoch of Reioniza- tion’ and the National Research Foundation of Korea to the Center for Galaxy Evolution Research (No. 2017R1A5A1070354).
© 2017 The Author(s).
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science