The Regulation of Galaxy Growth along the Size-Mass Relation by Star Formation, as Traced by H in KMOS 3D Galaxies at 0.7 z 2.7

David J. Wilman, Matteo Fossati, J. Trevor Mendel, Roberto Saglia, Emily Wisnioski, Stijn Wuyts, Natascha Förster Schreiber, Alessandra Beifiori, Ralf Bender, Sirio Belli, Hannah Übler, Philipp Lang, Jeffrey C. C. Chan, Rebecca L. Davies, Erica J. Nelson, Reinhard Genzel, Linda J. Tacconi, Audrey Galametz, Richard I. Davies, Dieter LutzSedona Price, Andreas Burkert, Ken-ichi Tadaki, Rodrigo Herrera-camus, Gabriel Brammer, Ivelina Momcheva, Pieter Van Dokkum

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We present half-light sizes measured from emission tracing star formation in 281 star-forming galaxies from the survey at . Sizes are derived by fitting 2D exponential disk models, with bootstrap errors averaging 20%. sizes are a median (mean) of 1.19 (1.26) times larger than those of the stellar continuum-which, due to radial dust gradients, places an upper limit on the growth in stellar size via star formation-with just intrinsic scatter. At fixed continuum size the size shows no residual trend with stellar mass, star formation rate, redshift, or morphology. The only significant residual trend is with the excess obscuration of by dust, at fixed continuum obscuration. The scatter in continuum size at fixed stellar mass is likely driven by the scatter in halo spin parameters. The stability of the ratio of size to continuum size demonstrates a high degree of stability in halo spin and in the transfer of angular momentum to the disk over a wide range of physical conditions and cosmic time. This may require local regulation by feedback processes. The implication of our results, as we demonstrate using a toy model, is that our upper limit on star-formation-driven growth is sufficient only to evolve star-forming galaxies approximately along the observed size-mass relation, consistent with the size growth of galaxies at constant cumulative comoving number density. To explain the observed evolution of the size-mass relation of star-forming disk galaxies, other processes, such as the preferential quenching of compact galaxies or galaxy mergers, may be required.

Original languageEnglish
Pages (from-to)1-27
Number of pages27
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 19 Mar 2020

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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