Oral Presentation

Reconstructing Initial Conditions from Pencil-Beam Galaxy Surveys

Author(s): Chenze Dong (Kavli IPMU)

Presenter: Chenze Dong (Kavli IPMU)

Density reconstruction has become a key tool for probing large-scale structure formation and galaxy evolution. When combined with constrained simulations, it enables detailed interpretation of cosmological and astrophysical parameters at the field level. However, conventional methods rely on dense, spatially well-sampled galaxy fields, restricting their application to low-redshift or wide-area surveys with extensive coverage. By contrast, many modern and forthcoming surveys targeting structure formation—such as Subaru/PFS and the Euclid Deep Field—cover narrow fields-of-view (~1 deg²), posing serious challenges for standard reconstruction pipelines. In this talk, I will present a novel framework for reconstructing initial conditions from pencil-beam surveys. It combines a forward model of structure formation (via JaxPM) with a dedicated optimization-based solver tailored to sparse, anisotropic geometries. I will demonstrate its performance on semi-analytic galaxies from the Millennium simulation, and explore its application to FLIMFLAM—an FRB foreground mapping project where accurate large-scale structure inference is essential. This work opens new avenues for applying structure reconstruction to next-generation deep-field surveys and contributes to the broader effort of reconstructing the universe from an increasingly galaxy survey dataset.