Astrochemical Modeling of Propargyl Radical Chemistry in TMC-1
arXiv:2309.07341 · doi:10.3847/1538-4357/acf863
Abstract
Recent detections of aromatic species in dark molecular clouds suggest formation pathways may be efficient at very low temperatures and pressures, yet current astrochemical models are unable to account for their derived abundances, which can often deviate from model predictions by several orders of magnitude. The propargyl radical, a highly abundant species in the dark molecular cloud TMC- 1, is an important aromatic precursor in combustion flames and possibly interstellar environments. We performed astrochemical modeling of TMC-1 using the three-phase gas-grain code NAUTILUS and an updated chemical network, focused on refining the chemistry of the propargyl radical and related species. The abundance of the propargyl radical has been increased by half an order of magnitude compared to the previous GOTHAM network. This brings it closer in line with observations, but it remains underestimated by two orders of magnitude compared to its observed value. Predicted abundances for the chemically related C4H3N isomers within an order of magnitude of observed values corroborate the high efficiency of CN addition to closed-shell hydrocarbons under dark molecular cloud conditions. The results of our modeling provide insight into the chemical processes of the propargyl radical in dark molecular clouds and highlight the importance of resonance-stabilized radicals in PAH formation.
31 pages and 17 figures (including the appendix), accepted for publication in The Astrophysical Journal
References in corpus (27)
- A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
- Detection of Two Interstellar Polycyclic Aromatic Hydrocarbons via Spectral Matched Filtering
- Non-thermal desorption from interstellar dust grains via exothermic surface reactions
- The 2014 KIDA network for interstellar chemistry
- Polycylcic Aromatic Hydrocarbons (PAH's) in dense cloud chemistry
- Binding energies: new values and impact on the efficiency of chemical desorption
- Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene (-CH) with GOTHAM Observations of TMC-1
- The effect of uncertainties on chemical models of dark clouds
- Discovery of Interstellar 2-Cyanoindene (2-CHCN) in GOTHAM Observations of TMC-1
- A New Reference Chemical Composition for TMC-1
- Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCHCN) in TMC-1
- Benzonitrile as a proxy for benzene in the cold ISM: low temperature rate coefficients for CN + CH
- The interstellar chemistry of C3H and C3H2 isomers
- Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
- Discovery of the propargyl radical (CH2CCH) in TMC-1: one of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds
- Gas phase Elemental abundances in Molecular cloudS (GEMS) VII. Sulfur elemental abundance
- Free Radicals in Superfluid Liquid Helium Nanodroplets: A Pyrolysis Source for the Production of Propargyl Radical
- Gas phase Elemental abundances in Molecular cloudS (GEMS). IV. Observational results and statistical trends
- Detection of Interstellar HCNC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 Conditions
- A study of C4H3N isomers in TMC-1: line by line detection of HCCCH2CN
- Detection of the propargyl radical at lambda 3 mm
- Desorption Kinetics and Binding Energies of Small Hydrocarbons
- CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N
- Predicting binding energies of astrochemically relevant molecules via machine learning
- Discovery of Interstellar trans-cyanovinylacetylene (HCCCH=CHCN) and vinylcyanoacetylene (HC=CHCN) in GOTHAM Observations of TMC-1
- Discovery of interstellar 3-cyano propargyl radical, CH2CCCN
- Laboratory observation and astronomical search of 1-cyano propargyl radical, HCCCHCN