Detecting Model Misspecification in Cosmology with Scale-Dependent Normalizing Flows

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Main Authors: Akhmetzhanova, Aizhan, Cuesta-Lazaro, Carolina, Mishra-Sharma, Siddharth
Format: Preprint
Published: 2025
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author Akhmetzhanova, Aizhan
Cuesta-Lazaro, Carolina
Mishra-Sharma, Siddharth
author_facet Akhmetzhanova, Aizhan
Cuesta-Lazaro, Carolina
Mishra-Sharma, Siddharth
contents Current and upcoming cosmological surveys will produce unprecedented amounts of high-dimensional data, which require complex high-fidelity forward simulations to accurately model both physical processes and systematic effects which describe the data generation process. However, validating whether our theoretical models accurately describe the observed datasets remains a fundamental challenge. An additional complexity to this task comes from choosing appropriate representations of the data which retain all the relevant cosmological information, while reducing the dimensionality of the original dataset. In this work we present a novel framework combining scale-dependent neural summary statistics with normalizing flows to detect model misspecification in cosmological simulations through Bayesian evidence estimation. By conditioning our neural network models for data compression and evidence estimation on the smoothing scale, we systematically identify where theoretical models break down in a data-driven manner. We demonstrate a first application to our approach using matter and gas density fields from three CAMELS simulation suites with different subgrid physics implementations.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05744
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Detecting Model Misspecification in Cosmology with Scale-Dependent Normalizing Flows
Akhmetzhanova, Aizhan
Cuesta-Lazaro, Carolina
Mishra-Sharma, Siddharth
Cosmology and Nongalactic Astrophysics
Instrumentation and Methods for Astrophysics
Machine Learning
Current and upcoming cosmological surveys will produce unprecedented amounts of high-dimensional data, which require complex high-fidelity forward simulations to accurately model both physical processes and systematic effects which describe the data generation process. However, validating whether our theoretical models accurately describe the observed datasets remains a fundamental challenge. An additional complexity to this task comes from choosing appropriate representations of the data which retain all the relevant cosmological information, while reducing the dimensionality of the original dataset. In this work we present a novel framework combining scale-dependent neural summary statistics with normalizing flows to detect model misspecification in cosmological simulations through Bayesian evidence estimation. By conditioning our neural network models for data compression and evidence estimation on the smoothing scale, we systematically identify where theoretical models break down in a data-driven manner. We demonstrate a first application to our approach using matter and gas density fields from three CAMELS simulation suites with different subgrid physics implementations.
title Detecting Model Misspecification in Cosmology with Scale-Dependent Normalizing Flows
topic Cosmology and Nongalactic Astrophysics
Instrumentation and Methods for Astrophysics
Machine Learning
url https://arxiv.org/abs/2508.05744