Detection of Two Interstellar Polycyclic Aromatic Hydrocarbons via Spectral Matched Filtering

TL;DR

This paper reports the first detection of two cyanated polycyclic aromatic hydrocarbons in space using spectral matched filtering, providing evidence for specific PAH molecules in the interstellar medium.

Contribution

It introduces a novel spectral matched filtering method to identify specific PAHs, leading to the first interstellar detection of cyanonaphthalene molecules.

Findings

Detection of 1- and 2-cyanonaphthalene in TMC-1

Spectral matched filtering effectively identifies PAHs in space

Discussion of possible formation pathways for these molecules

Abstract

Ubiquitous unidentified infrared emission bands are seen in many astronomical sources. Although these bands are widely, if not unanimously, attributed to the collective emission from polycyclic aromatic hydrocarbons, no single species from this class has been detected in space. We present the discovery of two -CN functionalized polycyclic aromatic hydrocarbons, 1- and 2-cyanonaphthalene, in the interstellar medium aided by spectral matched filtering. Using radio observations with the Green Bank Telescope, we observe both bi-cyclic ring molecules in the molecular cloud TMC-1. We discuss potential in situ gas-phase formation pathways from smaller organic precursor molecules.