Radiative stellar feedback in galaxy formation: Methods and physics

Philip F. Hopkins*, Michael Y. Grudić, Andrew Wetzel, Dušan Kereš, Claude André Faucher-Giguère, Xiangcheng Ma, Norman Murray, Nathan Butcher

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Radiative feedback (RFB) from stars plays a key role in galaxies, but remains poorly understood. We explore this using high-resolution, multifrequency radiation-hydrodynamics (RHD) simulations from the Feedback In Realistic Environments (FIRE) project. We study ultrafaint dwarf through Milky Way mass scales, including H+He photoionization; photoelectric, Lyman Werner, Compton, and dust heating; and single+multiple scattering radiation pressure (RP). We compare distinct numerical algorithms: ray-based LEBRON (exact when optically thin) and moments-based M1 (exact when optically thick). The most important RFB channels on galaxy scales are photoionization heating and single-scattering RP: in all galaxies, most ionizing/far-UV luminosity (∼1/2 of lifetime-integrated bolometric) is absorbed. In dwarfs, the most important effect is photoionization heating from the UV background suppressing accretion. In MW-mass galaxies, metagalactic backgrounds have negligible effects; but local photoionization and single-scattering RP contribute to regulating the galactic star formation efficiency and lowering central densities. Without some RFB (or other 'rapid' FB), resolved GMCs convert too-efficiently into stars, making galaxies dominated by hyperdense, bound star clusters. This makes star formation more violent and 'bursty' when SNe explode in these hyperclustered objects: thus, including RFB 'smoothes' SFHs. These conclusions are robust to RHD methods, but M1 produces somewhat stronger effects. Like in previous FIRE simulations, IR multiple-scattering is rare (negligible in dwarfs, ∼ 10 per cent of RP in massive galaxies): absorption occurs primarily in 'normal' GMCs with AV ∼ 1.

Original languageEnglish (US)
Pages (from-to)3702-3729
Number of pages28
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - 2020


  • Cosmology: theory
  • Galaxies: active
  • Galaxies: evolution
  • Galaxies: formation
  • Stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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