Universität zu Köln

Seifried, D., Sanchez-Monge, A., Suri, S. and Walch, S. (2017). Modelling the chemistry of star-forming filaments - II. Testing filament characteristics with synthetic observations. Mon. Not. Roy. Astron. Soc., 467 (4). S. 4467 - 4484. OXFORD: OXFORD UNIV PRESS. ISSN 1365-2966

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Abstract

We present synthetic continuum and (CO)-C-13 and (CO)-O-18 line emission observations of dense and cold filaments. The filaments are dynamically evolved using 3D-magnetohydrodynamic simulations that include one of the largest on-the-fly chemical networks used to date, which models the detailed evolution of H-2 and CO. We investigate the reliability of observable properties, in particular filament mass and width, under different simulation conditions like magnetic field orientation and cosmic ray ionization rate. We find that filament widths of similar to 0.1 pc can be probed with both line and continuum emission observations with a high accuracy (deviations <= 20 per cent). However, the width of more narrow filaments can be significantly overestimated by up to a factor of a few. Masses obtained via the dust emission are accurate within a few per cent whereas the masses inferred from molecular line emission observations deviate from the actual mass by up to a factor of 10 and show large differences for different J transitions. The inaccurate estimate of filament masses and widths of narrow filaments using molecular line observations can be attributed to (i) the non-isothermal state of the filaments, (ii) optical depth effects and (iii) the subthermally excited state of CO, while inclination effects and opacity correction only influence the obtained masses and widths by less than 50 per cent. Both, mass and width estimates, can be improved by using two isotopes to correct for the optical depth. Since gas and dust temperatures generally differ ( by up to 25 K), the filaments appear more gravitationally unstable if the (too low) dust temperature is used for the stability analysis.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Seifried, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sanchez-Monge, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Suri, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Walch, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-230583
DOI:	10.1093/mnras/stx399
Journal or Publication Title:	Mon. Not. Roy. Astron. Soc.
Volume:	467
Number:	4
Page Range:	S. 4467 - 4484
Date:	2017
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-2966
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TURBULENT MOLECULAR CLOUDS; INFRARED DARK CLOUDS; INTERSTELLAR-MEDIUM; HIGH-MASS; COLUMN DENSITIES; PRESTELLAR CORES; MAGNETIC-FIELDS; SERPENS SOUTH; CO CHEMISTRY; DENSE CORES Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23058