Universität zu Köln

Gaches, Brandt A. L., Offner, Stella S. R. and Bisbas, Thomas G. (2019). The Astrochemical Impact of Cosmic Rays in Protoclusters. I. Molecular Cloud Chemistry. Astrophys. J., 878 (2). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

We present astrochemical photodissociation region models in which cosmic-ray (CR) attenuation has been fully coupled to the chemical evolution of the gas. We model the astrochemical impact of CRs, including those accelerated by protostellar accretion shocks, on molecular clouds hosting protoclusters. Our models with embedded protostars reproduce observed ionization rates. We study the imprint of CR attenuation on ions for models with different surface CR spectra and different star formation efficiencies. We find that abundances, particularly ions, are sensitive to the treatment of CRs. We show the column densities of ions are underpredicted by the classic treatment of CRs by an order of magnitude. We also test two common chemistry approximations used to infer ionization rates. We conclude that the approximation based on the H-3(+) abundance underpredicts the ionization rate, except in regions where the CRs dominate the chemistry. Our models suggest the chemistry in dense gas will be significantly impacted by the increased ionization rates, leading to a reduction in molecules such as NH3 and causing H-2-rich gas to become [C II] bright.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Gaches, Brandt A. L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Offner, Stella S. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bisbas, Thomas G. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-137588
DOI:	10.3847/1538-4357/ab20c7
Journal or Publication Title:	Astrophys. J.
Volume:	878
Number:	2
Date:	2019
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ENERGETIC PARTICLE IRRADIATION; IONIZATION RATE; STAR-FORMATION; DENSE CORES; INTERSTELLAR CLOUDS; GALACTIC DISK; SILCC-ZOOM; C I; ACCRETION; AMMONIA Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/13758