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On the Formation of Density Filaments in the Turbulent Interstellar Medium

Xu, Siyao and Ji, Suoqing and Lazarian, A. (2019) On the Formation of Density Filaments in the Turbulent Interstellar Medium. Astrophysical Journal, 878 (2). Art. No. 157. ISSN 1538-4357. https://resolver.caltech.edu/CaltechAUTHORS:20190625-125512959

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Abstract

This study is motivated by recent observations of ubiquitous interstellar density filaments and guided by modern theories of compressible magnetohydrodynamic (MHD) turbulence. The interstellar turbulence shapes the observed density structures. As the fundamental dynamics of compressible MHD turbulence, perpendicular turbulent mixing of density fluctuations entails elongated density structures aligned with the local magnetic field, accounting for low-density parallel filaments seen in diffuse atomic and molecular gas. The elongation of low-density parallel filaments depends on the turbulence anisotropy. When taking into account the partial ionization, we find that the minimum width of parallel filaments in the cold neutral medium and molecular clouds is determined by the neutral–ion decoupling scale perpendicular to magnetic field. In highly supersonic MHD turbulence in molecular clouds, both low-density parallel filaments due to anisotropic turbulent mixing and high-density filaments due to shock compression exist.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ab21beDOIArticle
https://arxiv.org/abs/1905.06341arXivDiscussion Paper
ORCID:
AuthorORCID
Xu, Siyao0000-0002-0458-7828
Ji, Suoqing0000-0001-9658-0588
Additional Information:© 2019. The American Astronomical Society. Received 2017 December 30; revised 2019 April 5; accepted 2019 May 13; published 2019 June 25. S.X. acknowledges the support for Program number HST-HF2-51400.001-A provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. S.X. also thanks Chris McKee for useful conversations. S.J. acknowledges the support from the Sherman Fairchild Fellowship at Caltech. A.L. acknowledges the support from grant NSF DMS 1622353. Simulations were performed on Blue Waters supercomputer at NCSA, under the allocation PRAC NSF.1713353 supported by NSF. We have made use of NASA's Astrophysics Data System and the yt astrophysics analysis software suite (Turk et al. 2010).
Group:TAPIR, Walter Burke Institute for Theoretical Physics
Funders:
Funding AgencyGrant Number
NASAHST-HF2-51400.001
NASANAS5-26555
Sherman Fairchild FoundationUNSPECIFIED
NSFDMS-1622353
NSFPRAC-1713353
Subject Keywords:ISM: magnetic fields; ISM: structure; turbulence
Issue or Number:2
Record Number:CaltechAUTHORS:20190625-125512959
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190625-125512959
Official Citation:Siyao Xu et al 2019 ApJ 878 157
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96702
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:26 Jun 2019 14:24
Last Modified:03 Oct 2019 21:24

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