Components of star formation in NGC 253: Non-negative matrix factorization analysis with the ALCHEMI integrated intensity images

Abstract It is essential to examine the physical or chemical properties of molecular gas in starburst galaxies to reveal the underlying mechanisms characterizing starbursts. We used non-negative matrix factorization (NMF) to extract individual molecular or physical components involved in the star formation process in NGC 253. We used images of 148 transitions from 44 different species of the ALMA large program ALCHEMI. Additionally, we included the continuum images at ALMA Bands 3 and 7 from the same dataset. For the five NMF components (NF1–NF5), we obtained that their distributions correspond to various basic phenomena related to star formation: (i) low-density gas extended through the galactic central molecular zone (NF2), (ii) shocks (NF3), (iii) starburst regions (NF4), and (iv) young star-forming regions (NF5). The other component (NF1) is related to excitation; three components obtained by NMF (NF3, NF1, and NF5) show a strong dependence upon the upper state energies of transitions, and represent low, intermediate, and high excitation, respectively. We also compared our results using principal component analysis (PCA) previously applied to the same dataset. Molecular components extracted from NMF are similar to the ones obtained from PCA. However, NMF is better at extracting components associated with a single physical component, while a single component in PCA usually contains information on multiple physical components. This is especially true for features with weak intensities like emission from outflows. Our results suggest that NMF can be one of the promising methods for interpreting molecular line survey data, especially in the upcoming era of wide-band receivers.

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Journal
Publications of the Astronomical Society of Japan
Published
2024-10-28
DOI
https://doi.org/10.1093/pasj/psae095
Citations
2
Primary Topic
Stellar, planetary, and galactic studies
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article
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0.66

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article

Components of star formation in NGC 253: Non-negative matrix factorization analysis with the ALCHEMI integrated intensity images

Laura Colzi, Toshiki Saito, V. M. Rivilla, S. Aalto et al.
2 citations
Publications of the Astronomical Society of Japan
Stellar, planetary, and galactic studies
0.66
article

Components of star formation in NGC 253: Non-negative matrix factorization analysis with the ALCHEMI integrated intensity images

Laura Colzi, Toshiki Saito, V. M. Rivilla, S. Aalto, Y. Nishimura, S. Martín, Kazushi Sakamoto, Sebastian Müller, Nanase Harada, J. G. Mangum, S. Viti, C. Henkel, Mark Gorski, P. van der Werf, Ryo Kishikawa
article en
2 citations

Abstract

Abstract It is essential to examine the physical or chemical properties of molecular gas in starburst galaxies to reveal the underlying mechanisms characterizing starbursts. We used non-negative matrix factorization (NMF) to extract individual molecular or physical components involved in the star formation process in NGC 253. We used images of 148 transitions from 44 different species of the ALMA large program ALCHEMI. Additionally, we included the continuum images at ALMA Bands 3 and 7 from the same dataset. For the five NMF components (NF1–NF5), we obtained that their distributions correspond to various basic phenomena related to star formation: (i) low-density gas extended through the galactic central molecular zone (NF2), (ii) shocks (NF3), (iii) starburst regions (NF4), and (iv) young star-forming regions (NF5). The other component (NF1) is related to excitation; three components obtained by NMF (NF3, NF1, and NF5) show a strong dependence upon the upper state energies of transitions, and represent low, intermediate, and high excitation, respectively. We also compared our results using principal component analysis (PCA) previously applied to the same dataset. Molecular components extracted from NMF are similar to the ones obtained from PCA. However, NMF is better at extracting components associated with a single physical component, while a single component in PCA usually contains information on multiple physical components. This is especially true for features with weak intensities like emission from outflows. Our results suggest that NMF can be one of the promising methods for interpreting molecular line survey data, especially in the upcoming era of wide-band receivers.

Publications of the Astronomical Society of JapanVol. 77(1)
Northwestern University (US), Leiden University (NL), Shizuoka University (JP), Institute of Astronomy and Astrophysics, Academia Sinica (TW), The Graduate University for Advanced Studies, SOKENDAI (JP), National Radio Astronomy Observatory (US), Atacama Large Millimeter Submillimeter Array (CL), Xinjiang Astronomical Observatory (CN), EarthTech International (United States) (US), Institute of Astronomy (RU), Centro de Astrobiología (ES), European Southern Observatory (CL), Max Planck Institute for Radio Astronomy (DE), National Astronomical Observatory of Japan (JP), University College London (GB), Chalmers University of Technology (SE), Tokyo Metropolitan University (JP), The University of Tokyo (JP)
National Science Foundation, U.S. Nuclear Regulatory Commission, Ministerio de Ciencia, Innovación y Universidades, National Radio Astronomy Observatory, European Commission, European School of Oncology, Daiichi-Sankyo, Korea Astronomy and Space Science Institute, Ministry of Science and Technology, Taiwan, National Astronomical Observatory of Japan, Japan Society for the Promotion of Science, Consejo Superior de Investigaciones Científicas, National Institutes of Natural Sciences, European Regional Development Fund, Agencia Estatal de Investigación, European Social Fund
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