Suppression of star formation in low-mass galaxies caused by the reionization of their local neighbourhood

Journal Article · 20 July 2018 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/sty1945 · OSTI ID:1565768

Dawoodbhoy, Taha  ^[1]; Shapiro, Paul R. ^[1]; Ocvirk, Pierre ^[2]; Aubert, Dominique ^[2]; Gillet, Nicolas  ^[3]; Choi, Jun-Hwan ^[1]; Iliev, Ilian T.  ^[4]; Teyssier, Romain ^[5]; Yepes, Gustavo ^[6]; Gottlöber, Stefan ^[7]; D’Aloisio, Anson ^[8]; Park, Hyunbae ^[9]; Hoffman, Yehuda ^[10]

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1. Univ. of Texas, Austin, TX (United States)
2. Univ. de Strasbourg (France)
3. Univ. de Strasbourg (France); Scuola Normale Superiore, Pisa (Italy)
4. Univ. of Sussex, Brighton (United Kingdom)
5. Univ. of Zurich (Switzerland)
6. Univ. Autonoma de Madrid (Spain)
7. Leibniz-Inst. für Astrophysik Potsdam (AIP) (Germany)
8. Univ. of Texas, Austin, TX (United States); Univ. of California, Riverside, CA (United States). Dept. of Physics and Astronomy
9. Univ. of Texas, Austin, TX (United States); Korea Astronomy and Space Science Inst. Daejeon (Korea)
10. Hebrew Univ. of Jerusalem (Israel). Racah Inst. of Physics

Photoheating associated with reionization suppressed star formation in low-mass galaxies. Reionization was inhomogeneous, however, affecting different regions at different times. To establish the causal connection between reionization and suppression, we must take this local variation into account. We analyze the results of CoDa (‘Cosmic Dawn’) I, the first fully coupled radiation-hydrodynamical simulation of reionization and galaxy formation in the Local Universe, in a volume large enough to model reionization globally but with enough resolving power to follow all atomic-cooling galactic halos in that volume. For every halo identified at a given time, we find the redshift at which the surrounding IGM reionized, along with its instantaneous star formation rate (‘SFR’) and baryonic gas-to-dark matter ratio (M_gas/M_DM). The average SFR per halo with M < 10⁹M_⊙ was steady in regions not yet reionized, but declined sharply following local reionization. For M > 10¹⁰M_⊙, this SFR continued through local reionization, increasing with time, instead. For 10⁹M_⊙ < M < 10¹⁰M_⊙, the SFR generally increased modestly through reionization, followed by a modest decline. In general, halo SFRs were higher for regions that reionized earlier. A similar pattern was found for M_gas/M_DM, which declined sharply following local reionization for M < 10⁹M_⊙. Local reionization time correlates with local matter overdensity, which determines the local rates of structure formation and ionizing photon consumption. The earliest patches to develop structure and reionize ultimately produced more stars than they needed to finish and maintain their own reionization, exporting their ‘surplus’ starlight to help reionize regions that developed structure later.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Univ. of Texas, Austin, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21); National Science Foundation (NSF); National Aeronautic and Space Administration (NASA); French National Research Agency (ANR); Science and Technology Facilities Council (STFC) (United Kingdom); Deutsche Forschungsgemeinschaft (DFG) (Germany); Israel Science Foundation (ISF) European Commission (EC)
• OSTI ID: 1565768
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 2 Vol. 480; ISSN 0035-8711
• Publisher: Royal Astronomical SocietyCopyright Statement
• Country of Publication: United States
• Language: English