7 October 2026: Steven Ramnichal

Speaker: Steven Ramnichal (University of Bath)

Date: Wednesday 7 October 2026

Time: 14:00

Location: Physics 3.34

Panchromatic modelling of resolved high-z galaxy observations using 3D models of stars and dust

Galaxy growth has traditionally been explored through two complementary perspectives: the build-up of stellar mass inferred from galaxy integrated SED modelling, and the growth in size captured by high-resolution imaging. Together, these methods have driven substantial progress in our understanding of galaxy evolution. However, SED fitting typically relies on simplified assumptions, such as a foreground dust screen and a non-varying stellar population, limiting the physical realism of inferred properties. In parallel, increasingly rich datasets on high-redshift galaxies (from UV to mm) gathered from deep multi-wavelength observations suffer from differing spatial resolutions, resulting in a mixture of highly resolved, marginally resolved and unresolved data. To address both limitations, we developed a novel modelling technique aimed at maximally exploiting all of this rich yet varied information without sacrificing unresolved or poorly resolved bands, and without sacrificing resolution where available. The modelling approach is fundamentally 3D in nature, and extracts information on stellar populations and their radial variations as well as star-dust geometries, without imposing an attenuation law a priori. We jointly model observational constraints on wavelength dependent fluxes, sizes, Sérsic profile shapes, and axial ratios using a computationally efficient machine learning emulator trained on an extensive toy model library of dust radiative transfer calculations. Applications to TNG50 star forming galaxies and observations (ULTIMATE/PRIMER-UDS & JADES/GOODS-SOUTH) will be discussed in detail.