Recovery of the z>3 Galaxy Size-Mass Relationship from JWST Simulations

The launch of JWST will bring about a dramatic improvement in angular resolution in the infrared. One of many advances will be in our ability to develop a size-mass relationship for galaxies at higher redshifts than has been studied with previous observatories. We expect quiescent galaxies, or galaxies with little to no star formation, will be more compact at the same mass as their star forming counterparts, but this has not yet been investigated at z > 3 due to the wavelength limitations of Hubble. Prior to launch, we want to understand how well we can recover observed physical parameters of galaxies with varied masses with JWST NIRCam imaging data. To do this, we make use of simulated galaxies from the the SIMBA SPH simulations. Using snapshots covering z = 3-9, we find the distribution of masses in all the galaxies in that snapshot, and create a sample of the most massive galaxies for further study. We use the Python Line Of Sight Extinction by Ray-tracing (PYLOSER) software to create image stamps of these massive galaxies in the NIRCam filters, choosing the largest and brightest galaxies to measure their size and investigate a size-mass relationship for each redshift. We then include these galaxies in a set of simulated NIRCam imaging data being prepared for the Cosmic Evolution Early Release Science (CEERS) Survey. The CEERS team is using the Mirage software to produce raw and reduced NIRCam datasets. We will compare the input morphology and luminosity from SIMBA to the values we recover from our fully simulated JWST images, and explore how well the CEERS observations will constrain the size-mass relationship at z > 3.