36 GHz methanol lines from nearby galaxies: maser or quasi-thermal emission?
Humire, P.1; Henkel, C.1,2,3; Gong, Y.1; Leurini, S.1,4; Mauersberger, R.1; Levshakov, S. A.5,6,7; Winkel, B.1; Tarchi, A.4; Castangia, P.4; Malawi, A.2; Asiri, H.2; Ellingsen, S. P.8; McCarthy, T. P.8,9; Chen, X.10,11; Tang, X.3,12
Corresponding AuthorHenkel, C.(
AbstractMethanol (CH3OH) is one of the most abundant interstellar molecules, offering a vast number of transitions to be studied, including many maser lines. However, while the strongest Galactic CH3OH lines, the so-called class II masers, show no indications for the presence of superluminous counterparts in external galaxies, the less luminous Galactic class I sources appear to be different. Here we report class I 36 GHz (lambda approximate to 0.8 cm) CH3OH 4(-1) -> 3(0) E line emission from the nearby galaxies Maffei 2 (D approximate to 6 Mpc) and IC 342 (D approximate to 3.5 Mpc), measured with the 100 m telescope at Effelsberg at three different epochs within a time span of about five weeks. The 36 GHz methanol line of Maffei 2 is the second most luminous among the sources detected with certainty outside the Local Group of galaxies. This is not matched by the moderate infrared luminosity of Maffei 2. Higher-resolution data are required to check whether this is related to its prominent bar and associated shocks. Upper limits for M 82, NGC 4388, NGC 5728 and Arp 220 are also presented. The previously reported detection of 36 GHz maser emission in Arp 220 is not confirmed. Nondetections are reported from the related class I 44 GHz (lambda approximate to 0.7 cm) methanol transition towards Maffei 2 and IC 342, indicating that this line is not stronger than its 36 GHz counterpart. In contrast to the previously detected 36 GHz CH3OH emission in NGC 253 and NGC 4945, our 36 GHz profiles towards Maffei 2 and IC 342 are similar to those of previously detected nonmasing lines from other molecular species. However, by analogy to our Galactic center region, it may well be possible that the 36 GHz methanol lines in Maffei 2 and IC 342 are composed of a large number of faint and narrow maser features that remain spatially unresolved. In view of this, a search for a weak broad 36 GHz line component would also be desirable in NGC 253 and NGC 4945.
Keywordmasers galaxies: spiral galaxies: individual: IC 342 galaxies: individual: Maffei 2 galaxies: ISM radio lines: galaxies
Indexed BySCI
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000508200600002
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Document Type期刊论文
Corresponding AuthorHenkel, C.
Affiliation1.Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany
2.King Abdulaziz Univ, Fac Sci, Astron Dept, POB 80203, Jeddah 21589, Saudi Arabia
3.Chinese Acad Sci, Xinjiang Astron Observ, Urumqi 830011, Saudi Arabia
4.INAF Osserv Astron Cagliari, Via Sci 5, I-09047 Selargius, CA, Italy
5.Ioffe Phys Tech Inst, St Petersburg 194021, Russia
6.Electrotech Univ LETI, St Petersburg 197376, Russia
7.Petersburg Nucl Phys Inst, Gatchina 188300, Russia
8.Univ Tasmania, Sch Nat Sci, Hobart, Tas 7001, Australia
9.CSIRO, Australia Telescope Natl Facil, POB 76, Epping, NSW 1710, Australia
10.GuangZhou Univ, Ctr Astrophys, Guangzhou 510006, Peoples R China
11.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China
12.Chinese Acad Sci, Key Lab Radio Astron, Urumqi 830011, Peoples R China
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GB/T 7714
Humire, P.,Henkel, C.,Gong, Y.,et al. 36 GHz methanol lines from nearby galaxies: maser or quasi-thermal emission?[J]. ASTRONOMY & ASTROPHYSICS,2020,633:7.
APA Humire, P..,Henkel, C..,Gong, Y..,Leurini, S..,Mauersberger, R..,...&Tang, X..(2020).36 GHz methanol lines from nearby galaxies: maser or quasi-thermal emission?.ASTRONOMY & ASTROPHYSICS,633,7.
MLA Humire, P.,et al."36 GHz methanol lines from nearby galaxies: maser or quasi-thermal emission?".ASTRONOMY & ASTROPHYSICS 633(2020):7.
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