Purpose of the Program

Use HAWC+ to measure magnetic fields in nearby star-forming filaments.

Principal Investigator

Thushara Pillai (Boston University)

Proposal Abstract

Our understanding of star formation has been revolutionized by the insight that star-forming cores and hubs are embedded in complex filamentary networks that penetrate molecular clouds. Filaments differ greatly in their mass-to-length ratio -- which indicates the likelihood of star-forming fragmentation -- and the levels of associated star formation. Still, the exact role of filaments in star formation remains unclear. In particular, magnetic fields might play an important role, as indicated by well-ordered polarized dust emission that imply strong magnetic fields.

Here we propose SIMPLIFI, a SOFIA HAWC+ Legacy program that will carry out the first large-scale study of the magnetic polarization of filaments. The sample covers a wide range of mass-to-length ratios and star formation activities, in order to probe representative conditions for star formation. SIMPLIFI includes local filaments which are starless or are forming low-mass stars. SOFIA will resolve the column density and magnetic structure of filament ridges and cores much more clearly than previous work with Planck. SIMPLIFI also targets distant filaments that form clusters and massive stars, to reveal differences between regions of high-mass and and low-mass star formation. Our project brings together an international team of observers, instrumentalists, and theorists to exploit these data to the fullest. This enables us to go beyond the standard Davis–Chandrasekhar–Fermi analysis, e.g. by using sophisticated flux-freezing models and complex numerical MHD simulations. A further unique feature of SIMPLIFI is our access to comprehensive imaging of gas density distributions and dynamics from dust and line observations. This enables SIMPLIFI to constrain the relative role of self-gravity, turbulence, and magnetic fields in star formation. SIMPLIFI will clarify the role of magnetic fields in star-forming filaments, and will provide a framework to “simplify” the diversity of filament properties.