CSO and CARMA Observations of L1157. I. A Deep Search for Hydroxylamine (NH$_2$OH)

TL;DR

This study conducted a deep observational search for hydroxylamine, a potential precursor to glycine, in the L1157 outflow but found no detections, setting upper limits on its abundance in shocked regions.

Contribution

It provides the first sensitive upper limits on hydroxylamine abundance in L1157's shocked regions using CSO and CARMA observations.

Findings

No hydroxylamine detected in B1 and B2 shocks.

Derived upper limits on hydroxylamine column densities.

Estimated upper limits on hydroxylamine relative abundances.

Abstract

A deep search for the potential glycine precursor hydroxylamine (NH$_2$OH) using the Caltech Submillimeter Observatory (CSO) at $\lambda = 1.3$ mm and the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at $\lambda = 3$ mm is presented toward the molecular outflow L1157, targeting the B1 and B2 shocked regions. We report non-detections of NH$_2$OH in both sources. We a perform non-LTE analysis of CH$_3$OH observed in our CSO spectra to derive kinetic temperatures and densities in the shocked regions. Using these parameters, we derive upper limit column densities of NH$_2$OH of $\leq1.4 \times 10^{13}$~cm$^{-2}$ and $\leq1.5 \times 10^{13}$~cm$^{-2}$ toward the B1 and B2 shocks, respectively, and upper limit relative abundances of $N_{NH_2OH}/N_{H_2} \leq1.4 \times 10^{-8}$ and $\leq1.5 \times 10^{-8}$, respectively.