Structure analysis of simulated molecular clouds with the Δ-variance
Abstract
Here, we employ the Δ-variance analysis and study the turbulent gas dynamics of simulated molecular clouds (MCs). Our models account for a simplified treatment of time-dependent chemistry and the non-isothermal nature of the gas. We investigate simulations using three different initial mean number densities of n0 = 30, 100 and 300 cm-3 that span the range of values typical for MCs in the solar neighbourhood. Furthermore, we model the CO line emission in a post-processing step using a radiative transfer code. We evaluate Δ-variance spectra for centroid velocity (CV) maps as well as for integrated intensity and column density maps for various chemical components: the total, H2 and 12CO number density and the integrated intensity of both the 12CO and 13CO (J = 1 → 0) lines. The spectral slopes of the Δ-variance computed on the CV maps for the total and H2 number density are significantly steeper compared to the different CO tracers. We find slopes for the linewidth–size relation ranging from 0.4 to 0.7 for the total and H2 density models, while the slopes for the various CO tracers range from 0.2 to 0.4 and underestimate the values for the total and H2 density by a factor ofmore »
- Authors:
-
- Univ. Heidelberg, Heidelberg (Germany)
- Univ. Heidelberg, Heidelberg (Germany); Univ. of California, Santa Cruz, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Publication Date:
- Research Org.:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1329377
- Report Number(s):
- SLAC-PUB-16732
Journal ID: ISSN 0035-8711
- Grant/Contract Number:
- AC02-76SF00515
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Additional Journal Information:
- Journal Volume: 451; Journal Issue: 1; Journal ID: ISSN 0035-8711
- Publisher:
- Royal Astronomical Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 79 ASTRONOMY AND ASTROPHYSICS; ISM: clouds; ISM: molecules; galaxies: ISM
Citation Formats
Bertram, Erik, Klessen, Ralf S., and Glover, Simon C. O. Structure analysis of simulated molecular clouds with the Δ-variance. United States: N. p., 2015.
Web. doi:10.1093/mnras/stv948.
Bertram, Erik, Klessen, Ralf S., & Glover, Simon C. O. Structure analysis of simulated molecular clouds with the Δ-variance. United States. https://doi.org/10.1093/mnras/stv948
Bertram, Erik, Klessen, Ralf S., and Glover, Simon C. O. Wed .
"Structure analysis of simulated molecular clouds with the Δ-variance". United States. https://doi.org/10.1093/mnras/stv948. https://www.osti.gov/servlets/purl/1329377.
@article{osti_1329377,
title = {Structure analysis of simulated molecular clouds with the Δ-variance},
author = {Bertram, Erik and Klessen, Ralf S. and Glover, Simon C. O.},
abstractNote = {Here, we employ the Δ-variance analysis and study the turbulent gas dynamics of simulated molecular clouds (MCs). Our models account for a simplified treatment of time-dependent chemistry and the non-isothermal nature of the gas. We investigate simulations using three different initial mean number densities of n0 = 30, 100 and 300 cm-3 that span the range of values typical for MCs in the solar neighbourhood. Furthermore, we model the CO line emission in a post-processing step using a radiative transfer code. We evaluate Δ-variance spectra for centroid velocity (CV) maps as well as for integrated intensity and column density maps for various chemical components: the total, H2 and 12CO number density and the integrated intensity of both the 12CO and 13CO (J = 1 → 0) lines. The spectral slopes of the Δ-variance computed on the CV maps for the total and H2 number density are significantly steeper compared to the different CO tracers. We find slopes for the linewidth–size relation ranging from 0.4 to 0.7 for the total and H2 density models, while the slopes for the various CO tracers range from 0.2 to 0.4 and underestimate the values for the total and H2 density by a factor of 1.5–3.0. We demonstrate that optical depth effects can significantly alter the Δ-variance spectra. Furthermore, we report a critical density threshold of 100 cm-3 at which the Δ-variance slopes of the various CO tracers change sign. We thus conclude that carbon monoxide traces the total cloud structure well only if the average cloud density lies above this limit.},
doi = {10.1093/mnras/stv948},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 1,
volume = 451,
place = {United States},
year = {Wed May 27 00:00:00 EDT 2015},
month = {Wed May 27 00:00:00 EDT 2015}
}
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