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