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Title: The Importance of Preventive Feedback: Inference from Observations of the Stellar Masses and Metallicities of Milky Way Dwarf Galaxies

Dwarf galaxies are known to have remarkably low star formation efficiency due to strong feedback. Adopting the dwarf galaxies of the Milky Way (MW) as a laboratory, we explore a flexible semi-analytic galaxy formation model to understand how the feedback processes shape the satellite galaxies of the MW. Using Markov Chain Monte Carlo, we exhaustively search a large parameter space of the model and rigorously show that the general wisdom of strong outflows as the primary feedback mechanism cannot simultaneously explain the stellar mass function and the mass–metallicity relation of the MW satellites. An extended model that assumes that a fraction of baryons is prevented from collapsing into low-mass halos in the first place can be accurately constrained to simultaneously reproduce those observations. Here, the inference suggests that two different physical mechanisms are needed to explain the two different data sets. In particular, moderate outflows with weak halo mass dependence are needed to explain the mass–metallicity relation, and prevention of baryons falling into shallow gravitational potentials of low-mass halos (e.g., "pre-heating") is needed to explain the low stellar mass fraction for a given subhalo mass.
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [1] ; ORCiD logo [4] ; ORCiD logo [5] ; ORCiD logo [6]
  1. The Carnegie Institution for Science, Pasadena, CA (United States)
  2. The Carnegie Institution for Science, Pasadena, CA (United States); California Institute of Technology, Pasadena, CA (United States); Univ. of California, Davis, CA (United States)
  3. Univ. of Pittsburgh, Pittsburgh, PA (United States)
  4. The Ohio State Univ., Columbus, OH (United States)
  5. Univ. of Texas at Austin, Austin, TX (United States)
  6. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 846; Journal Issue: 1; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; galaxies: abundances; galaxies: dwarf; galaxies: evolution; galaxies: formation; Galaxy: evolution; Galaxy: formation
OSTI Identifier: