Exploring the formation pathways of formamide near young O-type stars

Abstract: Context. As a building block for amino acids, formamide (NH$_2$CHO) is an important molecule in astrobiology and astrochemistry, but its formation path in the interstellar medium is not understood well. Aims. We aim to find empirical evidence to support the chemical relationships of formamide to HNCO and H$_2$CO. Methods. We examine high angular resolution (~0.2") Atacama Large Millimeter/submillimeter Array (ALMA) maps of six sources in three high-mass star-forming regions and compare the spatial extent, integrated emission peak position, and velocity structure of HNCO and H$_2$CO line emission with that of NH$_2$CHO by using moment maps. Through spectral modeling, we compare the abundances of these three species. Results. In these sources, the emission peak separation and velocity dispersion of formamide emission is most often similar to HNCO emission, while the velocity structure is generally just as similar to H$_2$CO and HNCO (within errors). From the spectral modeling, we see that the abundances between all three of our focus species are correlated, and the relationship between NH$_2$CHO and HNCO reproduces the previously demonstrated abundance relationship. Conclusions. In this first interferometric study, which compares two potential parent species to NH$_2$CHO, we find that all moment maps for HNCO are more similar to NH$_2$CHO than H$_2$CO in one of our six sources (G24 A1). For the other five sources, the relationship between NH$_2$CHO, HNCO, and H$_2$CO is unclear as the different moment maps for each source are not consistently more similar to one species as opposed to the other.