The Galaxy Luminosity Functions in ASTRID: Predictions for LSST

TL;DR

This paper models galaxy luminosity functions using the ASTRID simulation, calibrates dust attenuation with SDSS data, and produces LSST-ready galaxy catalogs with detailed photometric predictions.

Contribution

It introduces a validated framework for predicting galaxy luminosity functions and photometry for LSST using hydrodynamical simulations and dust modeling.

Findings

Attenuated luminosity functions match observed galaxy statistics across wavelengths and redshifts.

Constructed mock catalogs with ~378 million galaxies for 0 <= z <= 2.

Provided Schechter parameters and galaxy counts for LSST survey planning.

Abstract

We present validated and forward-modelled galaxy luminosity functions and photometric predictions for the Vera C. Rubin Observatory Legacy Survey of Space and Time using the ASTRID cosmological hydrodynamical simulation. Galaxy magnitudes are computed by combining stellar population synthesis modeling with a physically motivated dust attenuation prescription in which the optical depth scales with metal surface density. The dust model is calibrated at z = 0 using SDSS luminosity functions and tested at intermediate redshifts (z = 0.5, 1.0, and 1.5) in rest-frame B, V , R, and I bands. We find that the attenuated luminosity functions reproduce observed galaxy statistics across multiple wavelengths and redshifts. Using this calibrated framework, we construct LSST-ready mock photometric catalogs over 0 <= z <= 2 in steps of Delta z = 0.1, containing ~378 million galaxies. We provide predicted apparent-magnitude luminosity functions in the LSST ugrizy bands, derive best-fit Schechter parameters as a compact analytic representation, and compute differential and cumulative galaxy number counts as a function of survey depth from Year 1 to Year 10.