Positron annihilation on polycyclic aromatic hydrocarbon molecules in the interstellar medium

2009/11/03 by Nidhal Guessoum, N. Guessoum, P. Jean +1
Chemistry · Engineering · Physics and Astronomy · #Abundance (ecology) #Annihilation #Astrobiology #Astrochemistry #Astrophysics #Astrophysics and Star Formation Studies #Chemistry #Dark Matter and Cosmic Phenomena #Electron #Galaxy #Hydrocarbon #Interstellar medium #Muon and positron interactions and applications #Nuclear physics #Organic chemistry #Physics #Polycyclic aromatic hydrocarbon #Positron #Positron annihilation #astro-ph.GA #astro-ph.HE

paper · pdf · doi:10.1111/j.1365-2966.2009.15954.x

Accepted in MNRAS, 10 pages, 5 figures

arxiv created 2009/11/03 · openalex publication_date 2009/12/15 · arxiv updated 2015/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We examine the annihilation of positrons on polycyclic aromatic hydrocarbon (PAH) molecules in interstellar medium (ISM) conditions. We estimate the annihilation rates of positrons on PAHs by a semi-empirical approach. We show that PAHs can play a significant role in the overall Galactic positron annihilation picture and use the annihilation rates and International Gamma-Ray Astrophysics Laboratory Galactic emission measurements to constrain the number of PAHs present in the ISM. We find an upper limit of 4.6 × 10−7 for the PAH abundance (by number, relative to hydrogen).

Citations

• Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating
• The mid-infrared colours of Galactic bulge, disc and Magellanic planetary nebulae
• An asymmetric distribution of positrons in the Galactic disk revealed by γ-rays
• Positron annihilation spectrum from the Galactic Centre region observed by SPI/INTEGRAL
• Electron‐Ion Recombination on Grains and Polycyclic Aromatic Hydrocarbons
• The mixed chemistry phenomenon in Galactic Bulge PNe
• The all-sky distribution of 511 keV electron-positron annihilation emission