Contribution Invited Talk
Gas-phase formation routes of complex organic molecules in the interstellar medium
Relatively complex organic molecules (COMs), such as formamide or cyanomethanimine, have been detected in the gas-phase of various regions of the interstellar medium. Some difficulties in assessing their formation routes under the harsh conditions of interstellar objects have progressively brought the current astrochemical models to privilege grain-surface over gas-phase chemistry to explain their formation. In this scenario, grain-surface chemistry is not only responsible for the hydrogenated molecules of the pre-collapse phase, but also for the whole set of the observed COMs (see, for instance, Garrod & Herbst 2006).
Nevertheless, as recently pointed out by a theoretical investigation of two gas-phase reactions leading to formamide and cyanomethanimine (Vazart et al. 2015, Barone et al. 2015), many gas-phase routes have actually been overlooked and not considered in the astrochemical models, while their inclusion with the parameters determined in laboratory experiments or via accurate theoretical calculations could be decisive in reproducing the observed abundances. In this contribution, we report on recent effort in searching for new formation routes of COMs in the gas-phase by: 1) extensive literature search of previously overlooked bimolecular reactions; 2) testing the new formation routes in astrochemical models. The approach is the same recently used to address the formation of methylformate starting from the parent molecule dimethylether via a set of bimolecular reactions which were studied in laboratory experiments in the 80’s but completely ignored in previous astrochemical models (Balucani et al. 2015).
R.T. Garrod and E. Herbst, 2006, A&A, 457, 927 F. Vazart, C. Latouche, D. Skouteris, N. Balucani, V. Barone, 2015, ApJ, in press. V. Barone, C. Latouche, D. Skouteris, F. Vazart, N. Balucani, B. Lefloch, C. Ceccarelli, MNRAS, submitted. N. Balucani, C. Ceccarelli and V. Taquet, 2015, MNRAS, 449, L16–L20