Abstract
Abstract
The atomic-to-molecular (H i-to-H2) transition in photodissociation regions (PDRs) has been investigated over the past several decades through analytic and numerical modeling. However, classical PDR models typically assume a uniform-density gas, ignoring the turbulent nature of the interstellar medium. Recently, Bialy et al. have presented a theoretical framework for studying the H i-to-H2 transition in a realistic turbulent medium with a nonhomogeneous density structure. Here we extend these turbulent-chemical models to explore the possibility of tracing the magnetic field direction in turbulent PDRs using the gradient technique. We utilize both subsonic and supersonic magnetohydrodynamic numerical simulations for chemical H i/H2 balance calculations. We confirm that the density fluctuations induced by turbulence can disperse the distribution of the H2 and H i fractions. We find that the energy spectrum of moment maps gets shallower when the sonic Mach number M
S increases. We explore the ability in magnetic field tracing of gradients of higher-order velocity centroids and compare their performance with that of traditional velocity centroid gradients (VCGs) and with intensity gradients (IGs). We find that the velocity gradients of the second-order centroids (VC2Gs) are more accurate than VCGs and IGs in probing the magnetic field orientation.
Publisher
American Astronomical Society
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
19 articles.
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