First Light And Reionisation Epoch Simulations (FLARES) IV: The size evolution of galaxies at $z\ge 5$

Abstract

We present the intrinsic and observed sizes of galaxies at $z\ge 5$ in the First Light And Reionisation Epoch Simulations (FLARES). We employ the large effective volume of FLARES to produce a sizeable sample of high redshift galaxies with intrinsic and observed luminosities and half light radii in a range of rest frame UV and visual photometric bands. This sample contains a significant number of intrinsically ultra-compact galaxies in the far-UV (1500 angstrom), leading to a negative intrinsic far-UV size-luminosity relation. However, after the inclusion of the effects of dust these same compact galaxies exhibit observed sizes that are as much as 50 times larger than those measured from the intrinsic emission, and broadly agree with a range of observational samples. This increase in size is driven by the concentration of dust in the core of galaxies, heavily attenuating the intrinsically brightest regions. At fixed luminosity we find a galaxy size redshift evolution with a slope of $m=1.21-1.87$ depending on the luminosity sample in question, and we demonstrate the wavelength dependence of the size-luminosity relation which will soon be probed by the Webb Space Telescope.

References in corpus (25)

• Array Programming with NumPy
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• The effect of photo-ionization on the cooling rates of enriched, astrophysical plasmas
• Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations
• The Evolution of Galaxy Structure over Cosmic Time
• Modelling discontinuities and Kelvin-Helmholtz instabilities in SPH
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• Inviscid SPH
• Half-mass radii for ~7,000 galaxies at 1.0 < z < 2.5: most of the evolution in the mass-size relation is due to color gradients
• Synthetic Galaxy Images and Spectra from the Illustris Simulation
• The redshift evolution of massive galaxy clusters in the MACSIS simulations
• Galaxy And Mass Assembly (GAMA): the wavelength-dependent sizes and profiles of galaxies revealed by MegaMorph
• The sizes of $z\sim 6-8$ lensed galaxies from the Hubble Frontier Fields Abell 2744 data
• Detailed dust modelling in the L-Galaxies semi-analytic model of galaxy formation
• The SINS/zC-SINF Survey of z~2 Galaxy Kinematics: Rest-frame Morphology, Structure, and Colors from Near-infrared Hubble Space Telescope Imaging
• Characterising and Identifying Galaxy Protoclusters
• Sizes of Lensed Lower-luminosity z=4-8 Galaxies from the Hubble Frontier Field Program
• Galaxy Sizes Since $z=2$ from the Perspective of Stellar Mass Distribution within Galaxies
• Dust Obscured Star Forming Galaxies in the Early Universe
• Dark-ages reionization and galaxy formation simulation--VII. The sizes of high-redshift galaxies
• Dark-ages Reionization and Galaxy Formation Simulation -- XVII. Sizes, angular momenta and morphologies of high redshift galaxies

Cited by in corpus (4)

• Two Remarkably Luminous Galaxy Candidates at $z\approx 10-12$ Revealed by JWST
• Early results from GLASS-JWST. V: the first rest-frame optical size-luminosity relation of galaxies at $z>7$
• First Light And Reionisation Epoch Simulations (FLARES) VII: The Star Formation and Metal Enrichment Histories of Galaxies in the early Universe
• First Light And Reionisation Epoch Simulations (FLARES) VI: The colour evolution of galaxies $z=5-15$