Toy models for galaxy formation versus simulations

By A. Dekel, A. Zolotov, Dylan Tweed, M. Cacciato, D. Ceverino, Joel R. Primack. 2013

211 citations recorded by the source corpus.

We describe simple useful toy models for key processes of galaxy formation in its most active phase, at z > 1, and test the approximate expressions against the typical behaviour in a suite of high-resolution hydro-cosmological simulations of massive galaxies at z = 4-1. We address in particular the evolution of (a) the total mass inflow rate from the cosmic web into galactic haloes based on the EPS approximation, (b) the penetration of baryonic streams into the inner galaxy, (c) the disc size, (d) the implied steady-state gas content and star-formation rate (SFR) in the galaxy subject to mass conservation and a universal star-formation law, (e) the inflow rate within the disc to a central bulge and black hole as derived using energy conservation and self-regulated Q ~ 1 violent disc instability (VDI), and (f) the implied steady state in the disc and bulge. The toy models provide useful approximations for the behaviour of the simulated galaxies. We find that (a) the inflow rate is proportional to mass and to (1+z)^5/2, (b) the penetration to the inner halo is ~50% at z = 4-2, (c) the disc radius is ~5% of the virial radius, (d) the galaxies reach a steady state with the SFR following the accretion rate into the galaxy, (e) there is an intense gas inflow through the disc, comparable to the SFR, following the predictions of VDI, and (f) the galaxies approach a steady state with the bulge mass comparable to the disc mass, where the draining of gas by SFR, outflows and disc inflows is replenished by fresh accretion. Given the agreement with simulations, these toy models are useful for understanding the complex phenomena in simple terms and for back-of-the-envelope predictions.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/7405134bd41500c1a6cfe173d6a03c7efeeebc31

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Citations in the corpus

The mass evolution of the first galaxies: stellar mass functions and star formation rates at 4 < z < 7 in the CANDELS GOODS-South field (2014, background): “This can be seen in the evolution of the specific accretion rate (Neistein & Dekel 2007; Dekel et al. 2013), ∝(1 + z)2.5, shown as the orange dashed line in Fig.”
A unified multiwavelength model of galaxy formation (2015, background): “Recently there has been some interest in the literature in simplified models of galaxy formation (Bouché et al. 2010; Dav´e et al. 2012; Dekel et al. 2013; Dekel & Mandelker 2014).”
Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge (2014, background): “MNRAS 449, 2087–2111 (2015) The time-scale for inflow is of the order of one or two disc orbital times (Dekel et al. 2009, 2013).”
Structural and Star-forming Relations since z ∼ 3: Connecting Compact Star-forming and Quiescent Galaxies (2015, methodology): “The strength and duration of these events declines with time following a decline in the gas reservoirs of SFGs (Dekel et al. 2013).”
Compaction and quenching of high-z galaxies in cosmological simulations: blue and red nuggets (2014, methodology): “This reflects the slow evolution of accretion rate in a growing galaxy (Dekel et al. 2013), the slow growth of stellar fraction in the total accreted baryons (Oser et al. 2010), and the evolution of SFR in the disc and bulge.”
Constraining the galaxy–halo connection over the last 13.3 Gyr: star formation histories, galaxy mergers and structural properties (2017, background): “…control the growth of their host galaxies (see e.g. Bouché et al. 2010; Dekel et al. 2009; Davé, Finlator & Oppenheimer 2012; Krumholz & Dekel 2012; Dekel et al. 2013; Dekel & Mandelker 2014; Mitra, Davé & Finlator 2015; Feldmann 2015; Feldmann & Mayer 2015; Rodŕıguez-Puebla et al. 2016b).”
Evolution of Interstellar Medium, Star Formation, and Accretion at High Redshift (2017, background): “Theoretical estimates for the halo accretion rate of baryons yield lower values at z ∼ 2 of 33 M yr −1 with a (1+z)2.5 dependence (Dekel et al. 2013), that is a somewhat slower redshift evolution.”
Neutral hydrogen in galaxy haloes at the peak of the cosmic star formation history (2014, result): “It is interesting to compare in more detail our predicted covering fractions with the results of Fumagalli et al. (2014), who used AMR simulations from Ceverino et al. (2010), Ceverino et al. (2012), and Dekel et al. (2013).”
The EAGLE project: Simulating the evolution and assembly of galaxies and their environments (2014, methodology): “…numerical experiments and analytic models provide some support for the general idea (e.g. Finlator & Davé 2008; Schaye et al. 2010; Booth & Schaye 2010; Davé et al. 2012; Haas et al. 2013a,b; Feldmann 2013; Dekel et al. 2013; Altay et al. 2013; Lilly et al. 2013; Sánchez Almeida et al. 2014).”
The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation (2014, background): “Several attempts have been made to reproduce the SFMS in hydrodynamical simulations of galaxies (e.g. Davé et al. 2011; Torrey et al. 2014) and (semi-)analytical models (e.g. Dutton et al. 2010; Davé et al. 2012; Dekel et al. 2013).”
Wet Disc Contraction to Galactic Blue Nuggets and Quenching to Red Nuggets (2013, background): “…the disc centres are naturally driven by the VDI (Gammie 2001; Dekel, Sari & Ceverino 2009; Krumholz & Burkert 2010; Burkert et al. 2010; Bournaud et al. 2011b; Forbes, Krumholz & Burkert 2012; Cacciato, Dekel & Genel 2012; Elmegreen, Zhang & Hunter 2012; Forbes et al. 2013; Dekel et al. 2013).”
KILOPARSEC-SCALE DUST DISKS IN HIGH-REDSHIFT LUMINOUS SUBMILLIMETER GALAXIES (2016, background): “…suggest that secular processes within star– forming galaxies are driving their gas and stars into the central regions, building up exponential disks and massive bulges without the need for major mergers (e.g., Elmegreen et al. 2008; Genzel et al. 2008; Dekel et al. 2009, 2013; Bournaud 2016).”
Evolution of density profiles in high-z galaxies: compaction and quenching inside-out (2015, background): “This has been confirmed in simulations (Dekel et al. 2013).”
A Redshift-independent Efficiency Model: Star Formation and Stellar Masses in Dark Matter Halos at z ≳ 4 (2018, background): “…et al. 2007a,b), but are sustained for extended periods of time in a quasi-steady state of gas inflow, gas outflow, and gas consumption (Bouché et al. 2010; Daddi et al. 2010; Genzel et al. 2010; Tacconi et al. 2010; Davé et al. 2012; Dekel et al. 2013; Lilly et al. 2013; Tacchella et al. 2016).”
Star formation in semi-analytic galaxy formation models with multiphase gas (2015, background): “…framework for understanding the behavior of the fairly complex intertwined suite of physical processes at play in state-of-the-art galaxy formation simulations is the “equilibrium model”, sometimes called the “bathtub model” (e.g. Davé et al. 2012; Dekel et al. 2013; Dekel & Mandelker 2014).”
Star formation sustained by gas accretion (2014, methodology): “Theory suggests that τg scales with the instantaneous Hubble time tH as τg ' 0.17 tH (Dekel et al. 2013).”
The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, background): “…Gyr−1) appears to be somewhat higher than the specific halo mass accretion rate (sAR, with sh ≈ 0.03 Gyr−1, as measured from another set of simulations in Dekel et al. 2013) over a wide range of redshifts, indicating a factor of ∼ 1.5 shorter e-folding time for the build up of stars compared with…”