OBSERVATIONAL RESULTS OF A MULTI-TELESCOPE CAMPAIGN IN SEARCH OF INTERSTELLAR UREA [(NH₂)₂CO]

Abstract

In this paper, we present the results of an observational search for gas phase urea [(NH 2 ) 2 CO] observed towards the Sgr B2(N-LMH) region. We show data covering urea transitions from ∼100 GHz to 250 GHz from five different observational facilities: BIMA, CARMA, the NRAO 12 m telescope, the IRAM 30 m telescope, and SEST. The results show that the features ascribed to urea can be reproduced across the entire observed bandwidth and all facilities by best fit column density, temperature, and source size parameters which vary by less than a factor of 2 between observations merely by adjusting for telescope-specific parameters. Interferometric observations show that the emission arising from these transitions is cospatial and compact, consistent with the derived source sizes and emission from a single species. Despite this evidence, the spectral complexity, both of (NH 2 ) 2 CO and of Sgr B2(N), makes the definitive identification of this molecule challenging. We present observational spectra, laboratory data, and models, and discuss our results in the context of a possible molecular detection of urea.

About the detection of urea in the interstellar medium: the energetic aspect

“…From this exhaustive study of the relative energies of the compounds that can be formed from the CH 4 N 2 O set of atoms, we found that there is no theoretical reason not to believe that the molecule observed towards the Sgr B2-LMH region during the multi-telescope campaign by Remijan et al (2014) is not urea. Following the same reasoning, thiourea is the sulphur analogue molecule to search for.…”

“…The important result that we suppose can be generalized to all environments is that the lower energy paths go through a tautomeric form of urea. At all events, the observations of urea in gas phase reported by Remijan et al (2014) are of utmost importance. In an earlier article, we suggested guidelines for "optimizing" the hunt of new species in the interstellar medium (ISM) by identifying the potentially more abundant isomers of a given chemical formula, i.e.…”

“…It has been recently proposed that urea, the well known molecular corner stone in the search for the origin of life, is the source of some weak mm-wave emission lines in the spectrum of the Sgr B2-LMH region (Remijan et al 2014). However, citing the authors of this study, ".…”

On the Formation of Amide Polymers via Carbonyl–amino Group Linkages in Energetically Processed Ices of Astrophysical Relevance

“…The methyl-substituted analog-acetamide (CH 3 CONH 2 )-was observed toward Sgr B2(N) with fractional abundances of 2×10 −11 to 2×10 −10 (Hollis et al 2006;Halfen et al 2011); a tentative detection of urea (CO(NH 2 ) 2 ) was reported by Remijan et al (2014) toward Sgr B2(N-LMH). Also, the very first mass spectra measured on a comet (67P/Churyumov Gerasimenko) revealed four new complex organic molecules (COM)-two of them (formamide and acetamide) carrying the peptide bond (Goesmann et al 2015).…”

Synthesis of Formamide and Related Organic Species in the Interstellar Medium via Chemical Dynamics Simulations

“…If one is interested in molecules in the interstellar medium (ISM), the list of organic and biological molecules detected is continually becoming larger. In addition to the well-known disputed case of the simplest amino acid, glycine (Kuan et al 2003;Snyder et al 2005;Cunningham et al 2007;Jones et al 2007), there have also been detections of molecules with (NH-C = O) peptide bond, like formamide (Rubin et al 1971), acetamide , and of other biologically relevant organic molecules like glycolaldehyde (the first sugar; Hollis et al 2000), urea (Remijan et al 2014), methyl acetate (Tercero et al 2013), acetaldehyde Fourikis et al 1974;Gilmore et al 1976), and amino acetonitrile (Belloche et al 2008).…”