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

Publications of the Astronomical Society of Japan, vol. 77, pp. 1–20

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.

Authors 15

1. Ryo Kishikawa corresponding

   Tokyo Metropolitan University

   Affiliation as printed

   Department of Physics, Tokyo Metropolitan University , 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 ,

   Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan

2. Nanase Harada

   The Graduate University for Advanced Studies, SOKENDAI · National Astronomical Observatory of Japan

   Affiliation as printed

   Astronomical Science Program, Graduate Institute for Advanced Studies , SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-1855 ,

   National Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588 ,

   Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo 181-1855, Japan

   National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

3. Toshiki Saito

   Shizuoka University · University of Shizuoka

   Affiliation as printed

   Faculty of Global Interdisciplinary Science and Innovation, Shizuoka University , 836 Ohya, Suruga-ku, Shizuoka 422-8529 ,

   Faculty of Global Interdisciplinary Science and Innovation, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan

4. S. Aalto

   Chalmers University of Technology

   Affiliation as printed

   Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory , SE-439 92 Onsala ,

   Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden

5. Laura Colzi

   Centro de Astrobiología

   Affiliation as printed

   Centro de Astrobiología (CAB), CSIC-INTA , Ctra. de Ajalvir Km. 4, 28850, Torrejón de Ardoz, Madrid ,

6. Mark Gorski

   Northwestern University

   Affiliation as printed

   Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University , Evanston, IL 60208 ,

   Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA

7. Christian Henkel

   Chinese Academy of Sciences · Xinjiang Astronomical Observatory · Max Planck Institute for Radio Astronomy

   Affiliation as printed

   Max-Planck-Institut für Radioastronomie , Auf dem Hügel 69, 53121 Bonn ,

   Xinjiang Astronomical Observatory, Chinese Academy of Sciences , 150 Science 1-Street, Urumqi, Xinjiang 830011 ,

   Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, Urumqi, Xinjiang 830011, China

8. J. G. Mangum

   National Radio Astronomy Observatory

   Affiliation as printed

   National Radio Astronomy Observatory , 520 Edgemont Road, Charlottesville, VA 22903-2475 ,

   National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA

9. S. Martín

   European Southern Observatory · Atacama Large Millimeter Submillimeter Array · European Southern Observatory

   Affiliation as printed

   European Southern Observatory , Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 ,

   Joint ALMA Observatory, Alonso de Córdova , 3107, Vitacura, Santiago 763-0355 ,

10. Sebastian Müller

    Chalmers University of Technology

    Affiliation as printed

    Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory , SE-439 92 Onsala ,

    Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden

11. Y. Nishimura

    The University of Tokyo

    Affiliation as printed

    Institute of Astronomy, Graduate School of Science, The University of Tokyo , 2-21-1 Osawa, Mitaka, Tokyo 181-0015 ,

    Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan

12. V. M. Rivilla

    Centro de Astrobiología

    Affiliation as printed

    Centro de Astrobiología (CAB), CSIC-INTA , Ctra. de Ajalvir Km. 4, 28850, Torrejón de Ardoz, Madrid ,

13. Kazushi Sakamoto

    Institute of Astronomy and Astrophysics, Academia Sinica · Academia Sinica

    Affiliation as printed

    Institute of Astronomy and Astrophysics, Academia Sinica , 11F of AS/NTU Astronomy-Mathematics Building, No.1, Sec. 4, Roosevelt Rd, Taipei 106216 ,

14. P. P. van der Werf Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University , P.O. Box 9513, 2300 RA Leiden,

    Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, the Netherlands

15. S. Viti Aachen Leiden Observatory

    Leiden University · Leiden Observatory · University College London

    Affiliation as printed

    Leiden Observatory, Leiden University , P.O. Box 9513, 2300 RA Leiden,

    Physics and Astronomy Department, University College London , Gower St, London, WC1E 6BT ,

    Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, the Netherlands

    Physics and Astronomy Department, University College London, Gower St, London, WC1E 6BT, UK