An Investigation of Spectral Line Stacking Techniques and Application to the Detection of HC$_{11}$N

TL;DR

This paper introduces a spectral line stacking method to detect complex molecules in space, successfully applying it to discover HC$_{11}$N, the largest cyanopolyyne in the interstellar medium, advancing molecular astrophysics.

Contribution

The paper presents a novel spectral line stacking technique for detecting new molecules in sparse spectral data, demonstrated by discovering HC$_{11}$N in space.

Findings

Discovered HC$_{11}$N in the interstellar medium.

Developed a method for detecting molecules with sparse spectral lines.

Enhanced understanding of interstellar molecular complexity.

Abstract

As the inventory of interstellar molecules continues to grow, the gulf between small species, whose individual rotational lines can be observed with radio telescopes, and large ones, such as polycyclic aromatic hydrocarbons (PAHs) best studied in bulk via infrared and optical observations, is slowly being bridged. Understanding the connection between these two molecular reservoirs is critical to understanding the interstellar carbon cycle, but will require pushing the boundaries of how far we can probe molecular complexity while still retaining observational specificity. Toward this end, we present a method for detecting and characterizing new molecular species in single-dish observations toward sources with sparse line spectra. We have applied this method to data from the ongoing GOTHAM (GBT Observations of TMC-1: Hunting Aromatic Molecules) Green Bank Telescope (GBT) large program, discovering six new interstellar species. In this paper we highlight the detection of HC$_{11}$N, the largest cyanopolyyne in the interstellar medium.