Digging into the Interior of Hot Cores with the ALMA (DIHCA). III. The Chemical Link between NH2CHO, HNCO, and H2CO

Abstract

Abstract We have analyzed the NH2CHO, HNCO, H2CO, and CH3CN (13CH3CN) molecular lines at an angular resolution of ∼0.″3 obtained by the Atacama Large Millimeter/submillimeter Array Band 6 toward 30 high-mass star-forming regions. The NH2CHO emission has been detected in 23 regions, while the other species have been detected toward 29 regions. A total of 44 hot molecular cores (HMCs) have been identified using the moment 0 maps of the CH3CN line. The fractional abundances of the four species have been derived at each HMC. In order to investigate pure chemical relationships, we have conducted a partial correlation test to exclude the effect of temperature. Strong positive correlations between NH2CHO and HNCO (ρ = 0.89) and between NH2CHO and H2CO (0.84) have been found. These strong correlations indicate their direct chemical links; dual-cyclic hydrogen addition and abstraction reactions between HNCO and NH2CHO and gas-phase formation of NH2CHO from H2CO. Chemical models including these reactions can reproduce the observed abundances in our target sources.