A New Framework for Multi-Line Analysis Combined Kernel PCA and Kernel SHAP: A Case of NGC 1068 ALMA Band 3 Data

Fuente: arXiv
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Main Authors: Okubo, Hiroma, Takeuchi, Tsutomu T., Akaho, Shotaro, Saito, Toshiki, Igarashi, Yasuhiko, Kuno, Nario, Harada, Nanase, Taniguchi, Akio, Takano, Shuro, Nakajima, Taku
Format: Preprint
Published: 2026
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author Okubo, Hiroma
Takeuchi, Tsutomu T.
Akaho, Shotaro
Saito, Toshiki
Igarashi, Yasuhiko
Kuno, Nario
Harada, Nanase
Taniguchi, Akio
Takano, Shuro
Nakajima, Taku
author_facet Okubo, Hiroma
Takeuchi, Tsutomu T.
Akaho, Shotaro
Saito, Toshiki
Igarashi, Yasuhiko
Kuno, Nario
Harada, Nanase
Taniguchi, Akio
Takano, Shuro
Nakajima, Taku
contents We present a new framework for multi-line analysis that combines kernel principal component analysis (Kernel PCA), an unsupervised machine-learning method, and Kernel SHapley Additive exPlanations (Kernel SHAP), an explainable artificial intelligence (XAI) technique. To enable a comparison with PCA-based studies, which have been widely used in multi-line analyses, we apply our framework to integrated intensity maps of 13 molecular lines from Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 archival data of the nearby galaxy NGC 1068. Previous PCA-based studies of NGC 1068 reported that physically meaningful structures are mainly captured up to the second component. In contrast, our framework can interpret physically meaningful features up to the fourth component. Furthermore, by comparing the results obtained from our framework with molecular column densities derived from local thermodynamical equilibrium (LTE) analysis, we suggest that the abundance of HCO+ is relatively enhanced in the molecular outflow region extending to a radius of about 400 pc from the galactic center, likely due to the effects of ultraviolet radiation and highly dense gas. These results show that our framework can provide data-driven insights into physical and chemical features that have not been clearly identified in previous studies. It also provides an efficient tool for interpreting the rapidly increasing amount of multi-line observational data.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14650
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A New Framework for Multi-Line Analysis Combined Kernel PCA and Kernel SHAP: A Case of NGC 1068 ALMA Band 3 Data
Okubo, Hiroma
Takeuchi, Tsutomu T.
Akaho, Shotaro
Saito, Toshiki
Igarashi, Yasuhiko
Kuno, Nario
Harada, Nanase
Taniguchi, Akio
Takano, Shuro
Nakajima, Taku
Astrophysics of Galaxies
We present a new framework for multi-line analysis that combines kernel principal component analysis (Kernel PCA), an unsupervised machine-learning method, and Kernel SHapley Additive exPlanations (Kernel SHAP), an explainable artificial intelligence (XAI) technique. To enable a comparison with PCA-based studies, which have been widely used in multi-line analyses, we apply our framework to integrated intensity maps of 13 molecular lines from Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 archival data of the nearby galaxy NGC 1068. Previous PCA-based studies of NGC 1068 reported that physically meaningful structures are mainly captured up to the second component. In contrast, our framework can interpret physically meaningful features up to the fourth component. Furthermore, by comparing the results obtained from our framework with molecular column densities derived from local thermodynamical equilibrium (LTE) analysis, we suggest that the abundance of HCO+ is relatively enhanced in the molecular outflow region extending to a radius of about 400 pc from the galactic center, likely due to the effects of ultraviolet radiation and highly dense gas. These results show that our framework can provide data-driven insights into physical and chemical features that have not been clearly identified in previous studies. It also provides an efficient tool for interpreting the rapidly increasing amount of multi-line observational data.
title A New Framework for Multi-Line Analysis Combined Kernel PCA and Kernel SHAP: A Case of NGC 1068 ALMA Band 3 Data
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2601.14650