Universität zu Köln

Girichidis, Philipp, Seifried, Daniel ORCID: 0000-0002-0368-9160, Naab, Thorsten ORCID: 0000-0002-7314-2558, Peters, Thomas, Walch, Stefanie, Wunsch, Richard ORCID: 0000-0003-1848-8967, Glover, Simon C. O. and Klessen, Ralf S. (2018). The SILCC project - V. The impact of magnetic fields on the chemistry and the formation of molecular clouds. Mon. Not. Roy. Astron. Soc., 480 (3). S. 3511 - 3541. OXFORD: OXFORD UNIV PRESS. ISSN 1365-2966

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Abstract

Magnetic fields are ubiquitously observed in the interstellar medium (ISM) of present-day star-forming galaxies with dynamically relevant energy densities. Using three-dimensional magnetohydrodynamic (MHD) simulations of the supernova-driven ISM in the flux-freezing approximation (ideal MHD), we investigate the impact of the magnetic field on the chemical and dynamical evolution of the gas, fragmentation, and the formation of molecular clouds. We follow the chemistry with a network of six species (H+, H, H-2, C+, CO, and free electrons) including local shielding effects. We find that magnetic fields thicken the disc by a factor of a few to a scale height of similar to 100 pc, delay the formation of dense (and molecular) gas by similar to 25 Myr, and result in differently shaped gas structures. The magnetized gas fragments into fewer clumps, which are initially at subcritical mass-to-flux ratios, M/Phi approximate to 0.3(M/Phi)(crit), and accrete gas preferentially parallel to the magnetic field lines until supercritial mass-toflux ratios of up to the order of 10 are reached. The accretion rates onto molecular clouds scale with M proportional to M-1.5. The median of the intercloud velocity dispersion is similar to 2 - 5 km s(-1) and lower than the internal velocity dispersion in the clouds (similar to 3 - 7 km s(-1)). However, individual cloud-cloud collisions occur at speeds of a few 10 km s(-1).

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Girichidis, Philipp UNSPECIFIED UNSPECIFIED UNSPECIFIED Seifried, Daniel UNSPECIFIED orcid.org/0000-0002-0368-9160 UNSPECIFIED Naab, Thorsten UNSPECIFIED orcid.org/0000-0002-7314-2558 UNSPECIFIED Peters, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Walch, Stefanie UNSPECIFIED UNSPECIFIED UNSPECIFIED Wunsch, Richard UNSPECIFIED orcid.org/0000-0003-1848-8967 UNSPECIFIED Glover, Simon C. O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Klessen, Ralf S. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-167176
DOI:	10.1093/mnras/sty2016
Journal or Publication Title:	Mon. Not. Roy. Astron. Soc.
Volume:	480
Number:	3
Page Range:	S. 3511 - 3541
Date:	2018
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-2966
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MULTIPHASE INTERSTELLAR-MEDIUM; MASSIVE STAR-FORMATION; SUPERNOVA-DRIVEN ISM; NEUTRAL ATOMIC PHASES; COLLAPSING DENSE CORE; GRAVITATIONAL-INSTABILITY; PROBABILITY-DISTRIBUTION; DIFFERENT ENVIRONMENTS; SUPERSONIC TURBULENCE; DYNAMICAL EVOLUTION Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16717