Letter | Published:

Suppression of star formation in dwarf galaxies by photoelectric grain heating feedback

Nature volume 535, pages 523525 (28 July 2016) | Download Citation


Photoelectric heating—heating of dust grains by far-ultraviolet photons—has long been recognized as the primary source of heating for the neutral interstellar medium1. Simulations of spiral galaxies2 have shown some indication that photoelectric heating could suppress star formation; however, simulations that include photoelectric heating have typically shown that it has little effect on the rate of star formation in either spiral galaxies3,4 or dwarf galaxies5, which suggests that supernovae are responsible for setting the gas depletion time in galaxies6,7,8. This result is in contrast with recent work9,10,11,12,13 indicating that a star formation law that depends on galaxy metallicity—as is expected with photoelectric heating, but not with supernovae—reproduces the present-day galaxy population better than does a metallicity-independent one. Here we report a series of simulations of dwarf galaxies, the class of galaxy in which the effects of both photoelectric heating and supernovae are expected to be strongest. We simultaneously include space- and time-dependent photoelectric heating in our simulations, and we resolve the energy-conserving phase of every supernova blast wave, which allows us to directly measure the relative importance of feedback by supernovae and photoelectric heating in suppressing star formation. We find that supernovae are unable to account for the observed14 large gas depletion times in dwarf galaxies. Instead, photoelectric heating is the dominant means by which dwarf galaxies regulate their star formation rate at any given time, suppressing the rate by more than an order of magnitude relative to simulations with only supernovae.

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J.C.F. and M.R.K. acknowledge support from Hubble Archival Research grant HST-AR-13909. This work was also supported by NSF grants AST-09553300 and AST-1405962, NASA ATP grant NNX13AB84G and NASA TCAN grant NNX14AB52G (J.C.F., M.R.K. and N.J.G.), and by Australian Research Council grant DP160100695. A.D. acknowledges support from the grants ISF 124/12, I-CORE Program of the PBC/ISF 1829/12, BSF 2014-273 and NSF AST-1405962. Simulations were carried out on NASA Pleiades and the UCSC supercomputer Hyades, supported by NSF grant AST-1229745.

Author information


  1. Department of Astronomy and Astrophysics, University of California, Santa Cruz, California 95064, USA

    • John C. Forbes
    •  & Mark R. Krumholz
  2. Research School of Astronomy and Astrophysics, Australian National University, Canberra, Australian Capital Territory 2611, Australia

    • Mark R. Krumholz
  3. National Center for Supercomputing Applications, University of Illinois, 1205 West Clark Street, Urbana-Champaign, Illinois 61820, USA

    • Nathan J. Goldbaum
  4. Center for Astrophysics and Planetary Sciences, Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel

    • Avishai Dekel


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J.C.F. and N.J.G. developed modifications to the publicly available Enzo code used in this work. The code was run and the results were analysed by J.C.F. The manuscript was written by J.C.F. and edited by all authors. The work was supervised and routinely advised by M.R.K. and A.D.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to John C. Forbes.

Reviewer Information Nature thanks R. Makiya and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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