Detection of antifreeze molecule ethylene glycol in the hot molecular core G358.93–0.03 MM1

The identification of complex pre-biotic molecules using millimetre and submillimetre telescopes allows us to understand how the basic building blocks of life are formed in the universe. In the interstellar medium, ethylene glycol (( CH₂ OH)₂) is the simplest sugar alcohol molecule, and it is the reduced alcohol of the simplest sugar-like molecule, glycolaldehyde (CH₂ OHCHO). We present the detection of the rotational emission lines of aGg conformer of ethylene glycol (( CH₂ OH)₂) towards the hot molecular core G358.93–0.03 MM1 using the Atacama Large Millimeter/Submillimeter Array. The estimated column density of aGg-( CH₂ OH)₂ towards the G358.93–0.03 MM1 is (4.5± 0.1)× 10¹⁶ cm⁻² with an excitation temperature of 155±35 K. The abundance of aGg-( CH₂ OH)₂ with respect to H₂ is (1.4± 0.5)× 10⁻⁸. Similarly, the abundances of aGg-( CH₂ OH)₂ with respect to CH₂ OHCHO and CH₃ OH are 3.1±0.5 and (6.1± 0.3)× 10⁻³. We compare the estimated abundance of aGg-( CH₂ OH)₂ with the existing three-phase warm-up chemical model abundance of ( CH₂ OH)₂, and we notice the observed abundance and modelled abundance are nearly similar. We discuss the possible formation pathways of aGg-( CH₂ OH)₂ towards the hot molecular cores, and we find that aGg-( CH₂ OH)₂ is probably created via the recombination of two CH₂ OH radicals on the grain surface of G358.93–0.03 MM1.