Formation of disc galaxies in preheated media: a preventative feedback model

Abstract

We introduce a semi-analytic galaxy formation model implementing a self-consistent treatment for the hot halo gas configuration and the assembly of central disks. Using the model, we explore a preventative feedback model, in which the circum-halo medium is assumed to be preheated up to a certain entropy level by early starbursts or other processes, and compare it with an ejective feedback model, in which baryons are first accreted into dark matter halos and subsequently ejected out by feedback. The model demonstrates that when the medium is preheated to an entropy comparable to the halo virial entropy the baryon accretion can be largely reduced and delayed. In addition, the preheated medium can establish an extended low density gaseous halo when it accretes into the dark matter halos, and result in a specific angular momentum of the cooling gas large enough to form central disks as extended as those observed. Combined with simulated halo assembly histories, the preventative feedback model can reproduce remarkably well a number of observational scaling relations. These include the cold baryon (stellar plus cold gas) mass fraction-halo mass relations, star formation histories, disk size-stellar mass relation and its evolution, and the number density of low-mass galaxies as a function of redshift. In contrast, the conventional ejective feedback model fails to reproduce these observational trends. Using the model, we demonstrate that the properties of disk galaxies are closely tied to the thermal state of hot halo gas and even possibly the circum-halo medium, which suggests that observational data for the disk properties and circum-galactic hot/warm medium may jointly provide interesting constraints for galaxy formation models.

On the galaxy–halo connection in the EAGLE simulation

“…Others that use additional physical assumptions find important correlations of size with variables beyond halo mass and spin, but neglect the scatter in sizes (e.g. Lu, Mo & Wechsler 2015). The empirical identification of the aspects of the galaxy-halo connection responsible for realistic size distributions -and correlations with velocity -will be of use in constraining such models and guiding the choice of inputs.…”

Little evidence for entropy and energy excess beyond r500 - An end to ICM preheating?

“…For example, these models predicted isentropic cores particularly in the low mass clusters (Ponman et al 2003) and an excess of entropy in the outskirts of the clusters (Voit et al 2003) which are not consistent with observations. The idea of preheating has endured and has found resurgence in recent times (see Pfrommer et al (2012); Lu et al (2015) and references therein). Pfrommer et al (2012) suggested time dependent entropy injection due to TeV blazars which provide uniform heat at z ∼ 3.5 peaking near z ∼ 1 and subsequent formation of CC (NCC) clusters by early forming groups (late forming groups) while Lu et al (2015) explored preventative scenario of feedback in which the circum-halo medium is heated to finite entropy.…”

Redshift evolution of stellar mass versus gas fraction relation in 0 <z< 2 regime: observational constraint for galaxy formation models

“…Ikeuchi 1986; Efstathiou 1992; Navarro & Steinmetz 1997; ⋆ E-mail:kana.matsui@nao.ac.jp; babajn@elsi.jp Gnedin 2000;Okamoto et al 2008), and preheating of the intergalactic medium (IGM) by gravitational pancaking (e.g. Mo et al 2005;Lu et al 2015) have been considered, while for high-mass galaxies, active galactic nucleus (AGN) feedback (e.g. Croton et al 2006) and gravitational heating (e.g.…”