How the Galaxy-Halo Connection Depends on Large-Scale Environment

Fuente: arXiv
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Autores principales: Wu, John F., Jespersen, Christian Kragh, Wechsler, Risa H.
Formato: Preprint
Publicado: 2024
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author Wu, John F.
Jespersen, Christian Kragh
Wechsler, Risa H.
author_facet Wu, John F.
Jespersen, Christian Kragh
Wechsler, Risa H.
contents We investigate the connection between galaxies, dark matter halos, and their large-scale environments at $z=0$ with Illustris TNG300 hydrodynamic simulation data. We predict stellar masses from subhalo properties to test two types of machine learning (ML) models: Explainable Boosting Machines (EBMs) with simple galaxy environment features and $\mathbb{E}(3)$-invariant graph neural networks (GNNs). The best-performing EBM models leverage spherically averaged overdensity features on $3$ Mpc scales. Interpretations via SHapley Additive exPlanations (SHAP) also suggest that, in the context of the TNG300 galaxy-halo connection, simple spherical overdensity on $\sim 3$ Mpc scales is more important than cosmic web distance features measured using the DisPerSE algorithm. Meanwhile, a GNN with connectivity defined by a fixed linking length, $L$, outperforms the EBM models by a significant margin. As we increase the linking length scale, GNNs learn important environmental contributions up to the largest scales we probe ($L=10$ Mpc). We conclude that $3$ Mpc distance scales are most critical for describing the TNG galaxy-halo connection using the spherical overdensity parameterization but that information on larger scales, which is not captured by simple environmental parameters or cosmic web features, can further augment these models. Our study highlights the benefits of using interpretable ML algorithms to explain models of astrophysical phenomena, and the power of using GNNs to flexibly learn complex relationships directly from data while imposing constraints from physical symmetries.
format Preprint
id arxiv_https___arxiv_org_abs_2402_07995
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle How the Galaxy-Halo Connection Depends on Large-Scale Environment
Wu, John F.
Jespersen, Christian Kragh
Wechsler, Risa H.
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
Instrumentation and Methods for Astrophysics
We investigate the connection between galaxies, dark matter halos, and their large-scale environments at $z=0$ with Illustris TNG300 hydrodynamic simulation data. We predict stellar masses from subhalo properties to test two types of machine learning (ML) models: Explainable Boosting Machines (EBMs) with simple galaxy environment features and $\mathbb{E}(3)$-invariant graph neural networks (GNNs). The best-performing EBM models leverage spherically averaged overdensity features on $3$ Mpc scales. Interpretations via SHapley Additive exPlanations (SHAP) also suggest that, in the context of the TNG300 galaxy-halo connection, simple spherical overdensity on $\sim 3$ Mpc scales is more important than cosmic web distance features measured using the DisPerSE algorithm. Meanwhile, a GNN with connectivity defined by a fixed linking length, $L$, outperforms the EBM models by a significant margin. As we increase the linking length scale, GNNs learn important environmental contributions up to the largest scales we probe ($L=10$ Mpc). We conclude that $3$ Mpc distance scales are most critical for describing the TNG galaxy-halo connection using the spherical overdensity parameterization but that information on larger scales, which is not captured by simple environmental parameters or cosmic web features, can further augment these models. Our study highlights the benefits of using interpretable ML algorithms to explain models of astrophysical phenomena, and the power of using GNNs to flexibly learn complex relationships directly from data while imposing constraints from physical symmetries.
title How the Galaxy-Halo Connection Depends on Large-Scale Environment
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2402.07995