Liu, ChuanwuMutch, Simon J.Poole, Gregory B.Angel, P. W.Duffy, Alan R.Geil, Paul M.Mesinger, AndreiWyithe, J. Stuart B.2025-12-232025-12-230035-8711ORCID:/0000-0001-7956-9758/work/195266046https://hdl.handle.net/1885/733796988We investigate high-redshift galaxy sizes using a semi-analytic model constructed for the Darkages Reionization And Galaxy-formation Observables from Numerical Simulation project. Our fiducial model, including strong feedback from supernovae and photoionization background, accurately reproduces the evolution of the stellarmass function and ultraviolet (UV) luminosity function. Using this model, we study the size-luminosity relation of galaxies and find that the effective radius scales with UV luminosity as Re ∝ L0.25 at z ~ 5-9. We show that recently discovered very luminous galaxies at z ~ 7 and 11 lie on our predicted size-luminosity relations. We find that a significant fraction of galaxies at z > 8 will not be resolved by James Webb Space Telescope, but Giant Magellan Telescope will have the ability to resolve all galaxies in haloes above the atomic cooling limit.We show that our fiducial model successfully reproduces the redshift evolution of average galaxy sizes at z > 5. We also explore galaxy sizes in models without supernova feedback. The no-supernova feedback models produce galaxy sizes that are smaller than observations.We therefore confirm that supernova feedback plays an important role in determining the size-luminosity relation of galaxies and its redshift evolution during reionization.This research was supported by the Victorian Life Sciences Computation Initiative (VLSCI), grant ref. UOM0005, on its Peak Computing Facility hosted at the University of Melbourne, an initiative of the Victorian Government, Australia. Part of this work was performed on the gSTAR national facility at Swinburne University of Technology. gSTAR is funded by Swinburne and the AustralianGovernments Education Investment Fund. This research programme is funded by the Australian Research Council through the ARC Laureate Fellowship FL110100072 awarded to JSBW. AM acknowledges support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 638809 AIDA).9enPublisher Copyright: © 2016 The Authors.Galaxies: evolutionGalaxies: formationGalaxies: fundamental parametersGalaxies: high-redshiftGalaxies: structure2016-11-1010.1093/mnras/stw291285014673142