Bistability in Interstellar Gas-Phase Chemistry

Abstract

We present an analysis of "bistability" in gas-phase chemical models of dark interstellar clouds. We identify the chemical mechanisms that allow high- and low-ionization solutions to the chemical rate-equations to coexist. We derive simple analytic scaling relations for the gas densities and ionization rates for which the chemistry becomes bistable. We explain why bistability is sensitive to the H3+ dissociative recombination rate coefficient, and why it is damped by gas-grain neutralization.

Accepted for publication in the Astrophysical Journal

Cited by in corpus (23)

• Chemistry of Dark Clouds: Databases, Networks, and Models
• 3D-PDR: A new three-dimensional astrochemistry code for treating Photodissociation Regions
• Overluminous HNC Line Emission in Arp220, NGC4418 and Mrk231 - Global IR Pumping or XDRs?
• Chemistry in Protoplanetary Disks: A Sensitivity Analysis
• Submillimeter ALMA Observations of the Dense Gas in the Low-Luminosity Type-1 Active Nucleus of NGC 1097
• A Unified Monte Carlo Treatment of Gas-Grain Chemistry for Large Reaction Networks. I. Testing Validity of Rate Equations in Molecular Clouds
• Chemistry in Cosmic-Ray Dominated Regions (CRDRs)
• Supernova enhanced cosmic ray ionization and induced chemistry in a molecular cloud of W51C
• CO/H2, C/CO, OH/CO, and OH/O2 in Dense Interstellar Gas: From High Ionization to Low Metallicity
• Cosmic ray induced ionisation of a molecular cloud shocked by the W28 supernova remnant
• Sensitivity of PDR Calculations to Microphysical Details
• TORUS-3DPDR: A self-consistent code treating three-dimensional photoionization and photodissociation regions
• Dense Molecular Gas around AGN: HCN/CO in NGC3227
• Chemical sensitivity to the ratio of the cosmic-ray ionization rates of He and H2 in dense clouds
• CO+ in M 82: A Consequence of Irradiation by X-rays
• Carbon isotope fractionation and depletion in TMC1
• The KOSMA-$\tau$ PDR Model -- I. Recent updates to the numerical model of photo-dissociated regions
• ALMA Observations of the Physical and Chemical Conditions in Centaurus A
• Sustained oscillations in Interstellar chemistry models
• Astrochemical Bistability: Autocatalysis in Oxygen Chemistry
• CO emission and CO hotspots in diffuse molecular gas
• Modelling the chemical evolution of molecular clouds as a function of metallicity
• New Bistable Solutions in Molecular Cloud Chemistry: Nitrogen and Carbon Autocatalysis