The Arecibo Arp 220 Spectral Census I: Discovery of the Pre-Biotic Molecule Methanimine and New Cm-wavelength Transitions of Other Molecules

An on-going Arecibo line search between 1.1 and 10 GHz of the prototypical starburst/megamaser galaxy, Arp 220, has revealed a spectrum rich in molecular transitions. These include the ``pre-biotic'' molecules: methanimine (CH\(_{2}\)NH) in emission, three \(v_{2}=1\) direct l-type absorpt...

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Bibliographic Details
Published in:arXiv.org 2008-05
Main Authors: Salter, C J, Ghosh, T, Catinella, B, Lebron, M, Lerner, M S, Minchin, R, Momjian, E
Format: Article
Language:English
Subjects:
Absorption
Formic acid
Galaxies
Methanol
Molecular gases
Star formation
Starburst galaxies
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Summary:An on-going Arecibo line search between 1.1 and 10 GHz of the prototypical starburst/megamaser galaxy, Arp 220, has revealed a spectrum rich in molecular transitions. These include the ``pre-biotic'' molecules: methanimine (CH\(_{2}\)NH) in emission, three \(v_{2}=1\) direct l-type absorption lines of HCN, and an absorption feature likely to be from either \(^{18}\)OH or formic acid (HCOOH). In addition, we report the detection of two, possibly three, transitions of \(\lambda\)4-cm excited OH not previously detected in Arp~220 which are seen in absorption, and a possible absorption feature from the 6.668-GHz line of methanol. This marks the first distant extragalactic detection of methanimine, a pre-biotic molecule. Also, if confirmed, the possible methanol absorption line presented here would represent the first extragalactic detection of methanol at a distance further than 10 Mpc. In addition, the strong, previously undetected, cm-wave HCN \(v_{2}=1\) direct l-type lines will aid the study of dense molecular gas and active star-forming regions in this starburst galaxy.
ISSN:2331-8422
DOI:10.48550/arxiv.0805.1205