期刊
ASTROPHYSICAL JOURNAL
卷 808, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/808/1/48
关键词
dust, extinction; ISM: kinematics and dynamics; magnetic fields; magnetohydrodynamics (MHD); molecular data; stars: formation; turbulence
资金
- NASA Einstein Fellowship
- NSF grant [AST 1212096]
- Center for Magnetic Self-organization in Laboratory and Astrophysical Plasmas (CMSO)
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1212096] Funding Source: National Science Foundation
We study the observable signatures of self-gravitating magnetohydrodynamics (MHD) turbulence by applying the probability density functions (PDFs) and the spatial density power spectrum to synthetic column density maps. We find that there exists three characterizable stages of the evolution of the collapsing cloud which we term early, intermediate, and advanced. At early times, i.e., t < 0.15t(ff), the column density has a power spectral slope similar to nongravitating supersonic turbulence and a lognormal distribution. At an intermediate stage, i.e., 0.15t(ff) < t <= 0.35t(ff), there exist signatures of the first cores in the shallower PDF and power spectrum power-law slopes. The column density PDF power-law tails at these times have line of sight averaged slopes ranging from -2.5 to -1.5 with shallower values belonging to simulations with lower magnetic field strength. The density power spectrum slope becomes shallow and can be characterized by P(k) = A(1)k(beta 2)e(-k/kc), where A(1) describes the amplitude, k(beta 2) describes the classical power-law behavior, and the scale k(c) characterizes the turn over from turbulence dominated to self-gravity dominated. At advanced stages of collapse, i.e., approximate to t > 0.35t(ff), the power spectral slope is positive valued, and a dramatic increase is observed in the PDF moments and the Tsallis incremental PDF parameters, which gives rise to deviations between PDF-sonic Mach number relations. Finally, we show that the imprint of gravity on the density power spectrum can be replicated in non-gravitating turbulence by introducing a delta-function with amplitude equivalent to the maximum valued point in a given self-gravitating map. We find that the turbulence power spectrum restored through spatial filtering of the high density material.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据