The TNG50-SKIRT Atlas: Post-processing methodology and first data release

Abstract

Galaxy morphology is a powerful diagnostic to assess the realism of cosmological hydrodynamical simulations. Determining the morphology of simulated galaxies requires the generation of synthetic images through 3D radiative transfer post-processing that properly accounts for different stellar populations and interstellar dust attenuation. We use the SKIRT code to generate the TNG50-SKIRT Atlas, a synthetic UV to near-infrared broadband image atlas for a complete stellar-mass selected sample of 1154 galaxies extracted from the TNG50 cosmological simulation at $z=0$. The images have a high spatial resolution (100 pc) and a wide field of view (160 kpc). In addition to the dust-obscured images, we also release dust-free images and physical parameter property maps with matching characteristics. As a sanity check and preview application we discuss the UVJ diagram of the galaxy sample. We investigate the effect of dust attenuation on the UVJ diagram and find that it affects both the star-forming and the quiescent galaxy populations. The quiescent galaxy region is polluted by younger and star-forming highly inclined galaxies, while dust attenuation induces a separation in inclination of the star-forming galaxy population, with low-inclination galaxies remaining at the blue side of the diagram and high-inclination galaxies systematically moving towards the red side. This image atlas can be used for a variety of other applications, including galaxy morphology studies and the investigation of local scaling relations. We publicly release the images and parameter maps, and we invite the community to use them.

The TNG50-SKIRT Atlas: Wavelength dependence of the effective radius

“…We interpret this as the result of the complex dependence of both population gradients and attenuation on galaxy morphology, stellar mass and environment. As discussed in Baes et al (2024), the TSA allows for a suite of applications, in particular concerning the link between intrinsic galaxy properties and galaxy morphology. In future papers we plan to use this image atlas to systematically investigate the wavelength dependence and the effects of dust attenuation on other morphological characteristics, derived from single or multiple-component Sérsic fitting or from a non-parametric morphological analysis.…”

“…The TSA (Baes et al 2024) is a synthetic image atlas for a complete stellar-mass selected sample of 1154 galaxies extracted from the TNG50 simulation (Pillepich et al 2019;Nelson et al 2019b). TNG50 is the highest-resolution version of the Illus-trisTNG suite of cosmological hydrodynamical simulations (Marinacci et al 2018;Naiman et al 2018;Nelson et al 2018;Pillepich et al 2018a;Springel et al 2018).…”

“…The dust masses are calculated by integrating the dust mass surface density maps. We note that the TNG50 hydrodynamical simulations do not explicitly contain a prescription for interstellar dust, so dust was added to the galaxies in post-processing using the assumption that the dust density is proportional to the gas metallicity in cold, dense gas (for details, see Trčka et al 2022;Baes et al 2024).…”

“…They can be disentangled, however, for simulated galaxies. In this work we use the TNG50-SKIRT Atlas (TSA, Baes et al 2024), a large multi-wavelength synthetic image atlas based on simulated galaxies extracted from the TNG50 cosmological hydrodynamics simulation (Pillepich et al 2019;Nelson et al 2019b), to investigate the origin of the wavelength dependence of the effective radius in the optical-NIR wavelength domain. Since dust attenuation can artificially be turned on and off, the relative contribution of the two contributors can be determined.…”

Calibrating Nonparametric Morphological Indicators from JWST Images for Galaxies over 0.5 < z < 3

“…This indicates a lack of some inhomogeneous substructures in the galaxies, determined by the methodology used by the Mock survey to generate the galaxy images, as shown in Snyder et al (2023). Some work uses the SKIRT code to consider radiative transfer to generate galaxies that are more consistent with observations (Baes et al 2024), but these data are only available for massive galaxies in the local Universe. If dust attenuation is considered in the galaxy images, then dust lanes or other substructures will appear in the shorter wavelength band, and these structures will make A O and M 20 more significant, bringing the morphology closer to observations.…”