Search for HOOH in Orion

TL;DR

This study investigates the presence of hydrogen peroxide (HOOH) in the Orion Molecular Cloud OMC A, aiming to understand its correlation with molecular oxygen and its role in star-forming regions, but the detection remains inconclusive due to spectral complexity.

Contribution

First search for HOOH in Orion OMC A, providing observational data and analysis of its potential correlation with O2 in star-forming clouds.

Findings

Detected HOOH emission at some transitions with >4 sigma significance.

High spectral line density complicates HOOH identification in Orion.

Detection status remains undecided due to possible contamination.

Abstract

Context: The abundance of key molecules determines the level of cooling that is necessary for the formation of stars and planetary systems. In this context, one needs to understand the details of the time dependent oxygen chemistry, leading to the formation of molecular oxygen and water. Aims: We aim to determine the degree of correlation between the occurrence of O2 and HOOH (hydrogen peroxide) in star-forming molecular clouds. We first detected O2 and HOOH in the rho Ophiuchi cloud (core A), we now search for HOOH in Orion Molecular Cloud OMC A, where O2 has also been detected. Methods: We mapped a 3 arcmin times 3 arcmin region around Orion H2-Peak 1 with the Atacama Pathfinder Experiment (APEX). In addition to several maps in two transitions of HOOH, viz. 219.17 GHz and 251.91 GHz, we obtained single-point spectra for another three transitions towards the position of maximum emission. Results: Line emission at the appropriate LSR-velocity (Local Standard of Rest) and at the level of greater or equal to 4 sigma was found for two transitions, with lower S/N (2.8 - 3.5 sigma) for another two transitions, whereas for the remaining transition, only an upper limit was obtained. The emitting region, offset 18 arcsec south of H2-Peak 1, appeared point-like in our observations with APEX. Conclusions: The extremely high spectral line density in Orion makes the identification of HOOH much more difficult than in rho Oph A. As a result of having to consider the possible contamination by other molecules, we left the current detection status undecided.