Diffhalos: A Generative Model of Cosmological Lightcones of Dark Matter Halos
Georgios Zacharegkas, Andrew P. Hearin, Alan Pearl, Matthew R. Becker, Florian Kéruzoré, Sara Ortega-Martinez
astro-ph.GA, astro-ph.CO
Submitted: 2026-07-11
Comments: 10 pages, 9 figures, source code publicly available at https://github.com/ArgonneCPAC/diffhalos
Code: https://github.com/ArgonneCPAC/diffhalos
License: http://creativecommons.org/licenses/by/4.0/
The gist: We present a generative model of cosmological lightcones of dark matter halos, Diffhalos.
Terminology
Abstract
We present a generative model of cosmological lightcones of dark matter halos, Diffhalos. In our model, we draw Monte Carlo samples of the halo mass function in a lightcone with a JAX-based implementation of the halo model, Halox, and we generate samples of subhalos by drawing from a model for the conditional subhalo mass function. We generate mass assembly histories (MAHs) using a normalizing flow trained on merger trees in cosmological N-body simulations. We show that Diffhalos can generate samples of halos, subhalos, and their MAHs with a statistical distribution that accurately approximates populations in simulated lightcones. As an example application, we use Diffhalos to calculate gradients of the halo and subhalo mass functions with respect to cosmological parameters. We conclude with a discussion of ongoing work using Diffhalos together with models of the galaxy--halo connection to make theoretical predictions for cosmological populations of galaxies, and to generate mock galaxy catalogs.
Sources
- DiffstarPop: A generative physical model of galaxy star formation history
- Connecting Galaxies with Halos Across Cosmic Time: Stellar mass assembly distribution modeling of galaxy statistics
- A Unified Halo Mass Function Across Dark Matter Models from High-Resolution Multi-Scale Simulations
- A universal model for the accretion rates and formation times of dark matter halos
- Web-Halo Model (WHM): Accurate non-linear matter power spectrum predictions without free parameters
- Population synthesis and astrophysical inference for high-$z$ JWST galaxies
- Synthetic light cone catalogues of modern redshift and weak lensing surveys with AbacusSummit
- Lightcone Construction for HACC Cosmological Simulations with LANTERN
- halox: Dark matter halo properties and large-scale structure calculations using JAX
- pmwd: A Differentiable Cosmological Particle-Mesh $N$-body Library
- DISCO-DJ II: a differentiable particle-mesh code for cosmology
- Efficiently emulating distribution functions in gigaparsec volumes for varying cosmological parameters
- FASTAR -- I. Continuous and differentiable evolutionary stellar population models
- FLORAH-Tree: Emulating Dark Matter Halo Merger Trees with Graph Generative Models
- Introducing sapphire: Towards Hybrid Physics-Informed, Data-Driven Modeling of Galaxy Formation
- Halo Lightcones with Optimised Orientation and Interpolation in Cosmological Simulations -- an application to mock H$\alpha$ selected galaxies
- The NumPy array: a structure for efficient numerical computation
- The dark matter halo mass function in the CDM cosmology at all times and over all scales -- from planetary to galaxy cluster masses
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