The influence of magnetic field on the CNM mass fraction and its alignment with density structures

Abstract

To contribute to the understanding of the magnetic field's influence on the segregation of CNM in the solar neighbourhood we analyse MHD simulations which include the main physical characteristics of the local neutral atomic ISM. The simulations have a continuous solenoidal Fourier forcing in a periodic box of 100 pc per side and an initial uniform magnetic field ($\overrightarrow{B_0}$) with intensities ranging between $\sim 0.4$ $\mu$G and $\sim 8$ $\mu$G. Our main results are: i) the CNM mass fraction diminishes with the increase in magnetic field intensity. ii) There is a preferred alignment between CNM structures and $\vec{B}$ in all our $B_0$ range but the preference weakens as $B_0$ increases. It is worth noticing that this preference is also present in two-dimensional projections making an extreme angle ($0$ or $\pi /2$) with respect to $\overrightarrow{B_0}$ and it is only lost for the strongest magnetic field when the angle of projection is perpendicular to $\overrightarrow{B_0}$. iii) The aforementioned results are prevalent despite the inclusion of self-gravity in our continuously forced simulations with a mean density similar to the average value of the solar neighbourhood. iv) Given a fixed $B_0$ and slightly higher mean densities, up to double, the effects of self-gravity are still not qualitatively significant.

20 pages, 17 figures

References in corpus (13)

• From the warm magnetized atomic medium to molecular clouds
• Vertical structure of a supernova-driven turbulent magnetized ISM
• The effect of magnetic fields on star cluster formation
• Rapid Molecular Cloud and Star Formation: Mechanisms and Movies
• Simulations of magnetized multiphase galactic disk regulated by supernovae explosions
• The supernova-regulated ISM. II. The mean magnetic field
• The 21-SPONGE HI Absorption Survey I: Techniques and Initial Results
• Formation of HI Clouds in Shock-compressed Interstellar Medium: Physical Origin of Angular Correlation Between Filamentary Structure and Magnetic Field
• Thermal Pressure in the Cold Neutral Medium of Nearby Galaxies
• The distribution of mean and fluctuating magnetic fields in the multi-phase ISM
• Molecular cloud formation in high-shear, magnetized colliding flows
• The impact of magnetic fields on the chemical evolution of the supernova-driven ISM
• C II radiative cooling of the Galactic diffuse interstellar medium: Insight about the star formation in Damped Lyman-alpha systems

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