TY - JOUR
T1 - Forming early-type galaxies without AGN feedback
T2 - A combination of merger-driven outflows and inefficient star formation
AU - Kretschmer, Michael
AU - Teyssier, Romain
N1 - Funding Information:
The authors thank the referee for their constructive comments that improved the quality of the paper. We acknowledge stimulating discussions with Robert Feldmann, Lucio Mayer, Robbert Verbeke, Renyue Cen, and Sandro Tacchella. This work was supported by the Swiss National Supercomputing Center (CSCS) project s890 – ‘Predictive models for galaxy formation’ and the Swiss National Science Foundation (SNSF) project 172535 – ‘Multiscale multiphysics models of galaxy formation’. The simulations in this work were performed on Piz Daint at the CSCS in Lugano, and the analysis was performed with equipment maintained by the Service and Support for Science IT, University of Zurich. We also made use of the PYNBODY package (Pontzen et al. 2013).
Publisher Copyright:
© 2019 The Author(s).
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Regulating the available gas mass inside galaxies proceeds through a delicate balance between inflows and outflows, but also through the internal depletion of gas due to star formation. At the same time, stellar feedback is the internal engine that powers the strong outflows. Since star formation and stellar feedback are both small-scale phenomena, we need a realistic and predictive subgrid model for both. We describe the implementation of supernova momentum feedback and star formation based on the turbulence of the gas in the RAMSES code. For star formation, we adopt the so-calledmultifreefallmodel. The resulting star formation efficiencies can be significantly smaller or bigger than the traditionally chosen value of 1 per cent. We apply these new numerical models to a prototype cosmological simulation of a massive halo that features a major merger which results in the formation of an early-type galaxy without using AGN feedback. We find that the feedback model provides the first-order mechanism for regulating the stellar and baryonic content in our simulated galaxy. At high redshift, the merger event pushes gas to large densities and large turbulent velocity dispersions, such that efficiencies come close to 10 per cent, resulting in large star formation rate (SFR). We find smallmolecular gas depletion time during the starburst, in perfect agreement with observations. Furthermore, at late times, the galaxy becomes quiescent with efficiencies significantly smaller than 1 per cent, resulting in small SFR and long molecular gas depletion time.
AB - Regulating the available gas mass inside galaxies proceeds through a delicate balance between inflows and outflows, but also through the internal depletion of gas due to star formation. At the same time, stellar feedback is the internal engine that powers the strong outflows. Since star formation and stellar feedback are both small-scale phenomena, we need a realistic and predictive subgrid model for both. We describe the implementation of supernova momentum feedback and star formation based on the turbulence of the gas in the RAMSES code. For star formation, we adopt the so-calledmultifreefallmodel. The resulting star formation efficiencies can be significantly smaller or bigger than the traditionally chosen value of 1 per cent. We apply these new numerical models to a prototype cosmological simulation of a massive halo that features a major merger which results in the formation of an early-type galaxy without using AGN feedback. We find that the feedback model provides the first-order mechanism for regulating the stellar and baryonic content in our simulated galaxy. At high redshift, the merger event pushes gas to large densities and large turbulent velocity dispersions, such that efficiencies come close to 10 per cent, resulting in large star formation rate (SFR). We find smallmolecular gas depletion time during the starburst, in perfect agreement with observations. Furthermore, at late times, the galaxy becomes quiescent with efficiencies significantly smaller than 1 per cent, resulting in small SFR and long molecular gas depletion time.
KW - Galaxies: evolution
KW - Galaxies: formation
KW - Galaxies: star formation
KW - Methods: numerical
KW - Stars: formation
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U2 - 10.1093/mnras/stz3495
DO - 10.1093/mnras/stz3495
M3 - Article
AN - SCOPUS:85079444495
SN - 0035-8711
VL - 492
SP - 1385
EP - 1398
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -