University of Tasmania
Browse
published_paper.pdf (606.04 kB)

Detection of a methanol megamaser in a major-merger galaxy

Download (606.04 kB)
journal contribution
posted on 2023-05-18, 07:04 authored by Chen, X, Simon EllingsenSimon Ellingsen, Baan, WA, Qiao, H-H, Li, J, An, T, Breen, SL
We have detected emission from both the 4_1 → 30 E (36.2 GHz) class I and 7_2 → 8_1 E (37.7 GHz) class II methanol transitions toward the center of the closest ultra-luminous infrared galaxy Arp 220. The emission in both methanol transitions shows narrow spectral features and has luminosities approximately 8 orders of magnitude stronger than those observed from typical class I methanol masers observed in Galactic star formation regions. The emission is also orders of magnitude stronger than the expected intensity of thermal emission from these transitions and based on these findings we suggest that the emission from the two transitions are masers. These observations provide the first detection of a methanol megamaser in the 36.2 and 37.7 GHz transitions and represent only the second detection of a methanol megamaser, following the recent report of an 84 GHz methanol megamaser in NGC 1068. We find that the methanol megamasers are significantly offset from the nuclear region and arise toward regions where there is Hα emission, suggesting that they are associated with starburst activity. The high degree of correlation between the spatial distribution of the 36.2 GHz methanol and X-ray plume emission suggests that the production of strong extragalactic class I methanol masers is related to galactic-outflow-driven shocks and perhaps cosmic rays. In contrast to OH and H2O megamasers which originate close to the nucleus, methanol megamasers provide a new probe of feedback (e.g., outflows) processes on larger scales and of star formation beyond the circumnuclear starburst regions of active galaxies.

History

Publication title

Astrophysical Journal Letters

Volume

800

Article number

L2

Number

L2

Pagination

1-5

ISSN

2041-8205

Department/School

School of Natural Sciences

Publisher

Institute of Physics Publishing

Place of publication

United Kingdom

Rights statement

Copyright 2015 The American Astronomical Society.

Repository Status

  • Open

Socio-economic Objectives

Expanding knowledge in the physical sciences

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC