Investigating the role of magnetic fields in star formation using molecular line profiles

TL;DR

This study uses advanced simulations and radiative transfer models to explore how magnetic fields influence molecular line profiles in star-forming regions, identifying potential observational diagnostics of magnetic criticality.

Contribution

It introduces a novel method combining MHD simulations with chemical and radiative transfer modeling to diagnose magnetic field importance in prestellar cores.

Findings

Peak intensity ratios of N₂H⁺ to CS can indicate magnetic criticality.

CS blue-to-red peak intensity ratio distinguishes subcritical from supercritical collapse.

L1498 likely formed from subcritical initial conditions despite current supercritical state.

Abstract

Determining the importance of magnetic fields in star forming environments is hampered by the difficulty of accurately measuring both field strength and gas properties in molecular clouds. We post-process three-dimensional non-ideal magnetohydrodynamic simulations of prestellar cores with a time-dependent chemical network, and use radiative transfer modelling to calculate self-consistent molecular line profiles. Varying the initial mass-to-flux ratio from sub- to super-critical results in significant changes to both the intensity and shape of several observationally important molecular lines. We identify the peak intensity ratio of N$_2$H$^+$ to CS lines, and the CS $J=2-1$ blue-to-red peak intensity ratio, as promising diagnostics of the initial mass-to-flux ratio, with N$_2$H$^+$/CS values of $>0.6$ ($<0.2$) and CS blue/red values of $<3$ ($>5$) indicating subcritical (supercritial) collapse. These criteria suggest that, despite presently being magnetically supercritical, L1498 formed from subcritical initial conditions.