Widespread Presence of Glycolaldehyde and Ethylene Glycol Around Sagittarius B2

TL;DR

This study detects widespread prebiotic molecules glycolaldehyde and ethylene glycol in Sagittarius B2, revealing their extensive distribution and suggesting formation at low temperatures in icy grain mantles, which has implications for astrochemistry.

Contribution

First spatial mapping of these molecules over a large region in Sagittarius B2, indicating their widespread presence and low-temperature formation pathways.

Findings

Molecules extend over 36 pc in Sagittarius B2.

Abundance decreases towards star-forming regions.

Supports formation in icy grain mantles at low temperatures.

Abstract

We report the detection of widespread CH$_2$OHCHO and HOCH$_2$CH$_2$OH emission in Galactic center giant molecular cloud Sagittarius B2 using the Shanghai Tianma 65m Radio Telescope. Our observations show for the first time that the spatial distribution of these two important prebiotic molecules extends over 15 arc-minutes, corresponding to a linear size of approximately 36 pc. These two molecules are not just distributed in or near the hot cores. The abundance of these two molecules seems to decrease from the cold outer region to the central region associated with star-formation activity. Results present here suggest that these two molecules are likely to form through a low temperature process. Recent theoretical and experimental studies demonstrated that prebiotic molecules can be efficiently formed in icy grain mantles through several pathways. However, these complex ice features cannot be directly observed, and most constraints on the ice compositions come from millimeter observations of desorbed ice chemistry products. These results, combined with laboratory studies, strongly support the existence of abundant prebiotic molecules in ices.