Over the past few decades, support for the importance of magnetic fields on the dynamics of evolving interstellar clouds has grown. Recently, various independent studies suggested the significance of magnetic fields on simple gas-phase chemistry, and vice versa. In this work, we test the interplay between magnetic fields and chemistry by utilizing a detailed gas-grain chemical network. Our focus lies on the chemical imprints that magnetic fields leave behind, especially on interstellar ices. We investigate the role of magnetic fields by simulating magnetized clouds with various field strengths, B=0,5,10 μG, during the evolution of an interstellar cloud from the diffuse atomic to the dense molecular phase. We find that with ideal magnetic fields, the cloud contraction is delayed around the trans-critical phase where C+ converts to C and CO, and where the freeze-out process commences. Due to the time-dependent nature of chemical reactions, especially for surface chemistry, this delay leaves an imprint on the chemical abundances. While the gaseous species are not strongly affected, aside from an enhancement of atomic carbon during the early phases of cloud evolution, ices show a stronger signature of magnetic fields. As the O2 ice abundance drops, CO2, formaldehyde, and methanol ices increase. The effect grows stronger with increasing magnetic field strength.

Chemical signatures in magnetized cloud cores

254th National Meeting (2017)

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