Methanol masers in NGC 253 with ALCHEMI
Por:
Humire P.K., Henkel C., Hernández-Gómez A., Martín S., Mangum J., Harada N., Muller S., Sakamoto K., Tanaka K., Yoshimura Y., Nakanishi K., Mühle S., Herrero-Illana R., Meier D.S., Caux E., Aladro R., Mauersberger R., Viti S., Colzi L., Rivilla V.M., Gorski M., Menten K.M., Huang K.-Y., Aalto S., Van Der Werf P.P., Emig K.L.
Publicada:
1 ene 2022
Resumen:
Context. Methanol masers of Class I (collisionally pumped) and Class II (radiatively pumped) have been studied in great detail in our Galaxy in a variety of astrophysical environments such as shocks and star-forming regions and are they are helpful to analyze the properties of the dense interstellar medium. However, the study of methanol masers in external galaxies is still in its infancy. Aims. Our main goal is to search for methanol masers in the central molecular zone (CMZ; inner 500 pc) of the nearby starburst galaxy NGC253. Methods. Covering a frequency range between 84 and 373 GHz (? = 3.6-0.8 mm) at high angular (1."6 ~ 27 pc) and spectral (~8-9 km s-1) resolution with ALCHEMI (ALMA Comprehensive High-resolution Extragalactic Molecular Inventory), we have probed dierent regions across the CMZ of NGC253. In order to look for methanol maser candidates, we employed the rotation diagram method and a set of radiative transfer models. Results.We detect for the first time masers above 84 GHz in NGC253, covering an ample portion of the J-1 (J-1)0-E line series (at 84, 132, 229, and 278 GHz) and the J0 (J-1)1 A series (at 95, 146, and 198 GHz). This confirms the presence of the Class I maser line at 84 GHz, which was already reported, but now being detected in more than one location. For the J-1 (J-1)0-E line series, we observe a lack of Class I maser candidates in the central star-forming disk. Conclusions. The physical conditions for maser excitation in the J-1 (J-1)0-E line series can be weak shocks and cloud-cloud collisions as suggested by shock tracers (SiO and HNCO) in bi-symmetric shock regions located in the outskirts of the CMZ. On the other hand, the presence of photodissociation regions due to a high star-formation rate would be needed to explain the lack of Class I masers in the very central regions. © 2022 P. K. Humire et al.
Filiaciones:
Max-Planck-Institut für Radioastronomie, Auf-dem-Hügel 69, Bonn, 53121, Germany
Astron. Dept., Faculty of Science, King Abdulaziz University, PO Box 80203, Jeddah, 21589, Saudi Arabia
Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, 830011, China
European Southern Observatory, Alonso de Córdova, 3107, Vitacura, Santiago, 763-0355, Chile
Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago, 763-0355, Chile
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, United States
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
Institute of Astronomy and Astrophysics, Academia Sinica, 11F of AS/NTU Astronomy-Mathematics Building, No.1, Sec. 4, Roosevelt Rd, Taipei, 10617, Taiwan
Department of Astronomy, School of Science, Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo, 181-1855, Japan
Department of Space Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, Onsala, 43992, Sweden
Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa, 223-8522, Japan
Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo, 181-0015, Japan
Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, Bonn, 53121, Germany
Institute of Space Sciences (ICE, CSIC, Campus UAB, Carrer de Magrans, Barcelona, 08193, Spain
New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, United States
National Radio Astronomy Observatory, PO Box O 1003 Lopezville Road, Socorro, NM 87801, United States
IRAP, Université de Toulouse, CNRS, UPS, CNES, Toulouse, France
Leiden Observatory, Leiden University, PO Box 9513, Leiden, 2300 RA, Netherlands
Department of Physics and Astronomy, University College London, Gower Street, London, WC1E6BT, United Kingdom
Centro de Astrobiologiá (CSIC-INTA), Ctra. de Torrejón a Ajalvir km 4, Torrejón de Ardoz, Madrid, 28850, Spain
All Open Access, Hybrid Gold
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