2022/01/31 by Sayantan Auddy, Shantanu Basu, Takahiro Kudoh · 6 citations
Earth and Planetary Sciences · Mathematics · Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Computer science #Field (mathematics) #Magnetic field #Mathematics #Molecular cloud #Physics #Quantum mechanics #Relation (database) #Star (game theory) #Stars #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/2041-8213/ac5a5a
published in The Astrophysical Journal Letters 928(1), L2 (IOP Publishing) · 6 pages, 3 Figures, 1 online animation, accepted in ApJL
openalex publication_date 2022/03/01 · arxiv created 2022/03/15 · arxiv updated 2022/03/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Abstract We study the magnetic field to density ( B – ρ ) relation in turbulent molecular clouds with dynamically important magnetic fields using nonideal three-dimensional magnetohydrodynamic simulations. Our simulations show that there is a distinguishable break density ρ T between the relatively flat low-density regime and a power-law regime at higher densities. We present an analytic theory for ρ T based on the interplay of the magnetic field, turbulence, and gravity. The break density ρ T scales with the strength of the initial Alfvén Mach number <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> </mml:math> for sub-Alfvénic ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo><</mml:mo> <mml:mn>1</mml:mn> </mml:math> ) and trans-Alfvénic ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>1</mml:mn> </mml:math> ) clouds. We fit the variation of ρ T for model clouds as a function of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">A</mml:mi> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> </mml:math> , set by different values of initial sonic Mach number <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic"></mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> </mml:math> and the initial ratio of gas pressure to magnetic pressure β 0 . This implies that ρ T , which denotes the transition in mass-to-flux ratio from the subcritical to the supercritical regime, is set by the initial turbulent compression of the molecular cloud.