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

C. J. Salter; T. Ghosh; B. Catinella; M. Lebron; M. S. Lerner; R. Minchin; E. Momjian

doi:10.1088/0004-6256/136/1/389

paper

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

arXiv:0805.1205 · doi:10.1088/0004-6256/136/1/389

Abstract

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 $λ$ 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.

arXiv comment25 pages, 10 figures. Accepted for publication in AJ

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

Abstract

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