magicc haloes: confronting simulations with observations of the circumgalactic medium at z=0

Abstract

We explore the circumgalactic medium (CGM) of two simulated star‐forming galaxies with luminosities L ≈ 0.1 and 1 L⋆ generated using the smooth particle hydrodynamic code gasoline. These simulations are part of the Making Galaxies In a Cosmological Context (magicc) program in which the stellar feedback is tuned to match the stellar mass–halo mass relationship. For comparison, each galaxy was also simulated using a ‘lower feedback’ (LF) model which has strength comparable to other implementations in the literature. The ‘magicc feedback’ (MF) model has a higher incidence of massive stars and an approximately two times higher energy input per supernova. Apart from the low‐mass halo using LF, each galaxy exhibits a metal‐enriched CGM that extends to approximately the virial radius. A significant fraction of this gas has been heated in supernova explosions in the disc and subsequently ejected into the CGM where it is predicted to give rise to substantial O vi absorption. The simulations do not yet address the question of what happens to the O vi when the galaxies stop forming stars. Our models also predict a reservoir of cool H i clouds that show strong Lyα absorption to several hundred kpc. Comparing these models to recent surveys with the Hubble Space Telescope, we find that only the MF models have sufficient O vi and H i gas in the CGM to reproduce the observed distributions. In separate analyses, these same MF models also show better agreement with other galaxy observables (e.g. rotation curves, surface brightness profiles and H i gas distribution). We infer that the CGM is the dominant reservoir of baryons for galaxy haloes.

The Properties of the Circumgalactic Medium in Red and Blue Galaxies: Results From the Cos-Gass+cos-Halos Surveys

“…In any event, we believe the data we have presented here provide a valuable observational resource for ongoing and future numerical simulations that try to reproduce CGM properties such as Lyαand metal-line column density profiles, covering fraction, and dynamics, such as line-widths and velocity spreads (for example Hummels et al 2012;Stinson et al 2012;Ford et al 2013Ford et al , 2014Ford et al , 2016Shen et al 2013;Fielding et al 2016;Kauffmann et al 2016;Liang et al 2016, and references therein). The ultimate goal is understanding the role of the CGM in the evolution of galaxies.…”

“…In any case, it appears that the CGM dynamics are not purely determined by gravitational forces alone. Because we expect that the absorption-line systems we see are imbedded in a multi-phase halo, their dynamics are likely to be influenced by processes such as drag forces, thermal instabilities, turbulent mixing, merger dynamics, and feedback-driven outflows (Maller & Bullock 2004;Santillan et al 2007;Kwak & Shelton 2010;Kwak et al 2011;Joung et al 2012aJoung et al , 2012bStinson et al 2012;Ford et al 2014;Suresh et al 2015;Fielding et al 2016).…”

The distribution of mass components in simulated disc galaxies

“…Further, the simulations match the evolution of the stellar mass-halo mass relation Kannan et al 2013), as derived by abundance matching (Moster et al 2013) and a range of relations at high redshift . The simulations also expel sufficient metals to match local observations (Prochaska et al 2011;Tumlinson et al 2011) of OVI in the circum-galactic medium (Stinson et al 2012;Brook et al 2012b). …”

Bimodality of low-redshift circumgalactic O vi in non-equilibrium eagle zoom simulations

“…Ford et al 2013Ford et al , 2016Suresh et al 2015a,b) and zooms with cosmological initial conditions (e.g. Stinson et al 2012;Hummels et al 2013;Shen et al 2014;Gutcke et al 2016) have found an intimate link between galaxies and their metal-enriched CGM. Simulations that specifically compared with the COS-Halos survey find lower O VI column densities than observed around star-forming galaxies (Suresh et al 2015b;Ford et al 2016).…”