Prebiotic precursors of the primordial RNA world in space: Detection of NH$_{2}$OH

TL;DR

This study reports the first detection of hydroxylamine (NH₂OH) in space, specifically in a molecular cloud near the Galactic Center, supporting theories of prebiotic molecule formation relevant to the origin of life.

Contribution

The paper presents the first observational detection of NH₂OH in the interstellar medium, providing insights into its formation pathways relevant to prebiotic chemistry.

Findings

Detected NH₂OH in the interstellar medium with abundance (2.1±0.9)×10⁻¹⁰

Detected five unblended or slightly blended rotational transitions of NH₂OH

Supports formation of NH₂OH via hydrogenation of NO on dust grains

Abstract

One of the proposed scenarios for the origin of life is the primordial RNA world, which considers that RNA molecules were likely responsible for the storage of genetic information and the catalysis of biochemical reactions in primitive cells, before the advent of proteins and DNA. In the last decade, experiments in the field of prebiotic chemistry have shown that RNA nucleotides can be synthesized from relatively simple molecular precursors, most of which have been found in space. An important exception is hydroxylamine, NH$_2$OH, which, despite several observational attempts, it has not been detected in space yet. Here we present the first detection of NH$_2$OH in the interstellar medium towards the quiescent molecular cloud G+0.693-0.027 located in the Galactic Center. We have targeted the three groups of transitions from the $J$=2$-$1, 3$-$2, and 4$-$3 rotational lines, detecting 5 transitions that are unblended or only slightly blended. The derived molecular abundance of NH$_2$OH is (2.1$\pm$0.9)$\times$10$^{-10}$. From the comparison of the derived abundance of NH$_2$OH and chemically related species, with those predicted by chemical models and measured in laboratory experiments, we favor the formation of NH$_2$OH in the interstellar medium via hydrogenation of NO on dust grain surfaces, with possibly a contribution of ice mantle NH$_3$ oxidation processes. Further laboratory studies and quantum chemical calculations are needed to completely rule out the formation of NH$_2$OH in the gas phase.