Abstract
We present the intrinsic and observed sizes of galaxies at z ≥ 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 Å), 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.
Original language | English |
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Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 514 |
Issue number | 2 |
Pages (from-to) | 1921–1939 |
ISSN | 0035-8711 |
DOIs | |
Publication status | Published - 2022 |
Keywords
- Galaxies: Evolution
- Galaxies: high-redshift
- Galaxies: photometry