Interstellar Carbodiimide (HNCNH) - A New Astronomical Detection from the GBT PRIMOS Survey via Maser Emission Features

TL;DR

This paper reports the first astronomical detection of interstellar carbodiimide (HNCNH) through maser emission features in the GBT PRIMOS survey, revealing its presence in hot, dense regions of Sgr B2(N).

Contribution

It is the first identification of HNCNH in space, detected via maser emission, expanding knowledge of interstellar isomers and their excitation mechanisms.

Findings

HNCNH detected in emission in Sgr B2(N)

Detected through maser amplification of specific transitions

HNCNH abundance estimated at ~10% of cyanamide

Abstract

In this work, we identify carbodiimide (HNCNH), which is an isomer of the well-known interstellar species cyanamide (NH2CN), in weak maser emission, using data from the GBT PRIMOS survey toward Sgr B2(N). All spectral lines observed are in emission and have energy levels in excess of 170 K, indicating that the molecule likely resides in relatively hot gas that characterizes the denser regions of this star forming region. The anticipated abundance of this molecule from ice mantle experiments is ~10% of the abundance of NH2CN, which in Sgr B2(N) corresponds to ~2 x 10^13 cm-2. Such an abundance results in transition intensities well below the detection limit of any current astronomical facility and, as such, HNCNH could only be detected by those transitions which are amplified by masing.