The Photolysis of Aromatic Hydrocarbons Adsorbed on the Surfaces of Cosmic Dust Grains

Murga, M. S.; Varakin, V. N.; Stolyarov, A. V.; Wiebe, D. S.

doi:10.1134/s1063772919080043

Cited by 4 publications

(2 citation statements)

References 34 publications

(51 reference statements)

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“…The dissociation rate of molecular hydrogen by cosmic-rays was taken according to Padovani et al (2018). The photochemistry experiments suggest that the photodissociation of adsorbed molecules is less efficient than the corresponding process in the gas phase (Öberg 2016;Murga et al 2019). Here we use solid/gas photodissociation coefficient ratio equal to 0.1 (Kalvāns 2018).…”

Section: Appendix A: Chemistrymentioning

confidence: 99%

C-type shock modelling – the effect of new H2–H collisional rate coefficients

Nesterenok

Bossion

Scribano

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We consider collisional excitation of H 2 molecules in C-type shocks propagating in dense molecular clouds. New data on collisional rate coefficients for (de-)excitation of H 2 molecule in collisions with H atoms and new H 2 dissociation rates are used. The new H 2 -H collisional data are state of the art and are based on the most accurate H 3 potential energy surface. We re-examine the excitation of rotational levels of H 2 molecule, the para-to-ortho-H 2 conversion, and H 2 dissociation by H 2 -H collisions. At cosmic ray ionization rates ζ 10 −16 s −1 and at moderate shock speeds, the H/H 2 ratio at the shock front is mainly determined by the cosmic ray ionization rate. The H 2 -H collisions play the main role in the para-to-ortho-H 2 conversion and, at ζ 10 −15 s −1 , in the excitation of vibrationally excited states of H 2 molecule in the shock. The H 2 ortho-to-para ratio (OPR) of the shocked gas and column densities of rotational levels of vibrationally excited states of H 2 are found to depend strongly on the cosmic ray ionization rate. We discuss the applicability of the presented results to interpretation of observations of H 2 emission in supernova remnants.

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Section: Appendix A: Chemistrymentioning

confidence: 99%

C-type shock modelling – the effect of new H2–H collisional rate coefficients

Nesterenok

Bossion

Scribano

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…We assume that aromatic grains (i.e., those that we consider to produce the mid-IR PAH features) aliphatize via the accretion of free elements. Using two-phase simulations, Murga et al (2019) and Hirashita & Murga (2020) find a fitting function for the aliphatization rate in terms of the grainsize distribution:…”

Section: Converting Between Aromatics and Aliphatesmentioning

confidence: 99%

A Framework for Modeling Polycyclic Aromatic Hydrocarbon Emission in Galaxy Evolution Simulations

Narayanan,

Smith,

Hensley

et al. 2023

ApJ

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We present a new methodology for simulating mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) in galaxy evolution simulations. To do this, we combine theoretical models of PAH emission features as they respond to varying interstellar radiation fields, grain-size distributions, and ionization states with a new model for dust evolution in galaxy simulations. We apply these models to three idealized arepo galaxy evolution simulations within the smuggle physics framework. We use these simulations to develop numerical experiments investigating the buildup of PAH masses and luminosities in galaxies in idealized analogs of the Milky Way, a dwarf galaxy, and a starburst disk. Our main results are as follows. Galaxies with high specific star formation rates have increased feedback energy per unit mass, and are able to shatter grains efficiently, driving up the fraction of ultrasmall grains. At the same time, in our model large radiation fields per unit gas density convert aliphatic grains into aromatics. The fraction of dust grains in the form of PAHs (q PAH) can be understood as a consequence of these processes, and in our model PAHs form primarily from interstellar processing (shattering) of larger grains rather than from the growth of smaller grains. We find that the hardness of the radiation field plays a larger role than variations in the grain-size distribution in setting the total integrated PAH luminosities, though cosmological simulations are necessary to investigate fully the complex interplay of processes that drive PAH band luminosities in galaxies.

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Experimental and theoretical studies of photoinduced reactions in the solid phase of the interstellar medium

Murga¹,

Wiebe²,

Vasyunin³

et al. 2020

Russ. Chem. Rev.

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The current state of laboratory studies modelling the photoinduced chemical reactions in the solid phase of the interstellar medium is considered. It is shown that multistage processes including physical adsorption of atoms and molecules from the gas phase of the interstellar medium, their drift over the cosmic dust surface, heterogeneous catalysis, photolysis, radiolysis and desorption of the final products and also the photochemical evolution of the dust grains themselves should be adequately included into the astrochemical models of the interstellar medium. The lack of data on the fundamental thermodynamic and kinetic parameters of photoreactions, needed for quantitative description of the physicochemical transformations in the solid phase of the interstellar medium, is noted. The bibliography includes 206 references.

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The Photolysis of Aromatic Hydrocarbons Adsorbed on the Surfaces of Cosmic Dust Grains

Cited by 4 publications

References 34 publications

C-type shock modelling – the effect of new H2–H collisional rate coefficients

C-type shock modelling – the effect of new H2–H collisional rate coefficients

A Framework for Modeling Polycyclic Aromatic Hydrocarbon Emission in Galaxy Evolution Simulations

Experimental and theoretical studies of photoinduced reactions in the solid phase of the interstellar medium

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