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Direct evidence for maser emission from the 36.2GHz class I transition of methanol in NGC253

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journal contribution
posted on 2023-05-19, 21:45 authored by Chen, X, Simon EllingsenSimon Ellingsen, Shen, Z-Q, McCarthy, TP, Zhong, W-Y, Deng, H
Observations made with the Jansky Very large Array (JVLA) at an angular resolution of ∼0."1 have detected class I methanol maser emission from the 36.2 GHz transition toward the starburst galaxy NGC 253. The methanol emission is detected toward four sites which lie within the regions of extended methanol emission detected in previous lower angular resolution (a few arcseconds) observations. The peak flux densities of the detected compact components are in the range 3-9 mJy beam-1. Combining the JVLA data with single-dish observations from the Shanghai Tianma Radio Telescope (TMRT) and previous interferometric observations with the Australia Telescope Compact Array (ATCA), we show that the 36.2 GHz class I methanol emission consists of both extended and compact structures, with typical scales of ∼6'' (0.1 kpc) and ∼0."05 (1 pc), respectively. The strongest components have a brightness temperature of >103 K, much higher than the maximum kinetic temperature (∼100 K) of the thermal methanol emission from NGC 253. Therefore, these observations conclusively demonstrate for the first time the presence of maser emission from a class I methanol transition in an external galaxy.

History

Publication title

Astrophysical Journal Letters

Volume

856

Article number

L35

Number

L35

Pagination

1-6

ISSN

2041-8205

Department/School

School of Natural Sciences

Publisher

Institute of Physics Publishing Ltd.

Place of publication

United Kingdom

Rights statement

Copyright 2018 The American Astronomical Society. Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0) https://creativecommons.org/licenses/by/3.0/

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  • Open

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Expanding knowledge in the physical sciences

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