The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation

By M. Sparre, C. Hayward, Volker Springel, M. Vogelsberger, Shy Genel, P. Torrey, D. Nelson, D. Sijacki, L. Hernquist. 2014

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Understanding the physical processes that drive star formation is a key challenge for galaxy formation models. In this paper, we study the tight correlation between the star formation rate (SFR) and stellar mass of galaxies at a given redshift, how halo growth influences star formation, and star formation histories of individual galaxies. We study these topics using Illustris, a state-of-the-art cosmological hydrodynamical simulation of galaxy formation. Illustris reproduces the observed relation (the star formation main sequence, SFMS) between SFR and stellar mass at redshifts z = 0 and 4, but at intermediate redshifts of z ≃ 1–2, the simulated SFMS has a significantly lower normalization than reported by observations. The scatter in the relation is consistent with the observed scatter. However, the fraction of outliers above the SFR–stellar mass relation in Illustris is less than that observed. Galaxies with halo masses of ∼10^12 M_⊙ dominate the SFR density of the Universe, in agreement with the results of abundance matching. Furthermore, more-massive galaxies tend to form the bulk of their stars at high redshift, which indicates that ‘downsizing’ occurs in Illustris. We also studied the star formation histories of individual galaxies, including the use of a principal component analysis decomposition. We find that for fixed stellar mass, galaxies that form earlier have more-massive black holes at z = 0, indicating that star formation and black hole growth are tightly linked processes in Illustris. While many of the properties of normal star-forming galaxies are well reproduced in the Illustris simulation, forming a realistic population of starbursts will likely require higher resolution and probably a more sophisticated treatment of star formation and feedback from stars and black holes.

Subfields: Astronomy and Astrophysics, Global and Planetary Change, Instrumentation

View Paper: https://www.semanticscholar.org/paper/02f5be89f4a5c3c0d8b6a62e40b2e04495ece922

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Citations in the corpus

The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, background): “All, hydrodynamic simulations of galaxies (e.g., Davé et al. 2011; Dekel et al. 2013; Torrey et al. 2014; Sparre et al. 2015), semi-analytical models (e.g., Dutton et al. 2010; Davé et al. 2012; Mitchell et al. 2014) and analytical models (e.g., Bouché et al. 2010; Dekel et al. 2013; Lilly et…”
simba: Cosmological simulations with black hole growth and feedback (2019, background): “During Cosmic Noon, it has long been seen that cosmological models tend to underpredict the main sequence amplitude (Daddi et al. 2007; Davé 2008; Narayanan et al. 2012; Sparre et al. 2015; Somerville & Davé 2015), typically by a factor of 2− 3.”
The stellar mass assembly of galaxies in the Illustris simulation: growth by mergers and the spatial distribution of accreted stars (2015, background): “…these trends are explained by the fact that massive galaxies have mergers more frequently than smaller galaxies, while at the same time their star formation rate is substantially suppressed by AGN feedback (see Sparre et al. 2015, for a discussion of star formation and its scatter in Illustris).”
(Star)bursts of FIRE: observational signatures of bursty star formation in galaxies (2015, background): “The star formation histories of galaxies simulated with explicit ‘resolved’ feedback are typically more bursty than when a sub-resolution ISM model is used; the latter typically result in a SFR variability timescale of & 100 Myr (Sparre et al. 2015).”
The Illustris simulation: the evolving population of black holes across cosmic time (2014, background): “…so we cannot conclude much about the evolution of the MBH - Mbulge relation at the very massive end or about whether the relatively large scatter seen in observations especially for the SMGs is reproduced (but see also Sparre et al. 2015 who find a too low fraction of starbursts in Illustris).”
The Horizon-AGN simulation: evolution of galaxy properties over cosmic time (2016, methodology): “…simulations that are comparable to Horizon-AGN generally show consistency with the observed star formation main sequence (e.g. Furlong et al. 2015; Sparre et al. 2015), although in some cases offsets of ∼ 0.2−0.4 dex are seen in the normalization of the predicted sequences compared to the…”
MUFASA: Galaxy Formation Simulations With Meshless Hydrodynamics (2016, background): “At z = 4, Illustris and EAGLE do somewhat better than Mufasa, as our fiducial Mufasa run produces too low a GSMF.”
UniverseMachine: The correlation between galaxy growth and dark matter halo assembly from z = 0−10 (2018, unknown): “This coincides with existing tensions between SSFRs from observations and SSFRs from modern hydrodynamical simulations (e.g., Sparre et al. 2015; Davé et al. 2016), as well as tensions between IR and SED-fit SFR indicators (Fang et al. 2018): SFRobs−SFRtrue = µ +κ exp ( − (z−2) 2 2 ) (25) The prior…”
The star formation activity of IllustrisTNG galaxies: main sequence, UVJ diagram, quenched fractions, and systematics (2018, background): “These at-face-value findings are in agreement with what outlined also for the original Illustris model (see e.g. Sparre et al. 2015, Genel et al. 2014 and Davidzon et al. 2018), even though the Illustris’ MS is higher than the TNG ones, and by several other works that compared the observed MS with…”
The origin and evolution of the galaxy mass–metallicity relation (2015, background): “Many cosmological simulations tend to form too many stars at early times (e.g. Davé et al. 2011a; Sparre et al. 2015; Fiacconi et al. 2015; for a review, see Somerville & Davé 2014.”
Near infrared spectroscopy and star-formation histories of 3 ≤ z ≤ 4 quiescent galaxies (2018, background): “…density significantly exceeds that predicted by state-of-the-art cosmological simulations, with and without AGN feedback (e.g., Wellons et al. 2015; Sparre et al. 2015; Davé et al. 2016), and requires a formation channel at z > 5 with SFRs larger than observed in the mostly dustfree Lyman-break…”
The COSMOS2015 galaxy stellar mass function . Thirteen billion years of stellar mass assembly in ten snapshots (2017, methodology): “In addition, as mentioned above, we use two GALAXEV templates that represent starburst galaxies with an increasing SFH (Behroozi et al. 2013; da Cunha et al. 2015; Sparre et al. 2015).”
THE SFR–M* RELATION AND EMPIRICAL STAR FORMATION HISTORIES FROM ZFOURGE AT 0.5 < z < 4 (2015, background): “This offset ranges between 0.17− 0.45 dex at fixed stellar mass and decreases with redshift (Sparre et al. 2015).”
How Stellar Feedback Simultaneously Regulates Star Formation and Drives Outflows (2015, background): “…(Sparre et al. 2015b), whereas galaxies in the FIRE simulations have SFRs that can vary by multiple orders of magnitude on 100-Myr timescales (Hopkins et al. 2014; Muratov et al. 2015; Sparre et al. 2015a), although resolution is another crucial difference between these two types of simulations.”
Galaxy morphology and star formation in the Illustris Simulation at z = 0 (2015, background): “There are hints that compact or spheroidal starbursts populate the highly star-forming sides of this distribution (see also Sparre et al. 2015).”