Detection and chemical modelling of complex prebiotic molecule cyanamide in the hot molecular core G31.41+0.31

Abstract: In the interstellar medium (ISM), the complex prebiotic molecule cyanamide (NH${2}$CN) plays a key role in producing adenine (C${5}$H${5}$N${5}$), purines (C${5}$H${4}$N${4}$), pyrimidines (C${4}$H${4}$N${2}$), and other biomolecules via a series of reactions. Therefore, studying the emission lines of NH${2}$CN is important for understanding the hypothesis of the pre-solar origin of life in the universe. We present the detection of the rotational emission lines of NH${2}$CN with vibrational states $v$ = 0 and 1 towards the hot molecular core G31.41+0.31 using the high-resolution twelve-meter array of Atacama Large Millimeter/Submillimeter Array (ALMA) band 3. The estimated column density of NH${2}$CN towards G31.41+0.31 using the local thermodynamic equilibrium (LTE) model is (7.21$\pm$0.25)$\times$10$^{15}$ cm$^{-2}$ with an excitation temperature of 250$\pm$25 K. The abundance of NH${2}$CN with respect to H${2}$ towards G31.41+0.31 is (7.21$\pm$1.46)$\times$10$^{-10}$. The NH${2}$CN and NH${2}$CHO column density ratio towards G31.41+0.31 is 0.13$\pm$0.02. We compare the estimated abundance of NH${2}$CN with that of other hot cores and corinos and observed that the abundance of NH${2}$CN towards G31.41+0.31 is nearly similar to that of the hot molecular core G358.93$-$0.03 MM1, the hot corinos IRAS 16293-2422 B, and NGC 1333 IRAS4A2. We compute the two-phase warm-up chemical model of NH${2}$CN using the gas-grain chemical code UCLCHEM, and after chemical modelling, we notice that the observed and modelled abundances are nearly similar. After chemical modelling, we conclude that the neutral-neutral reaction between NH${2}$ and CN is responsible for the production of NH${2}$CN on the grain surface of G31.41+0.31.