Oral Presentation

Is there a relationship between the Cosmic-Ray Ionization Rate / Ionization Fraction and Protostellar Disk Radius?

Author(s): Travis J. Thieme (ASIAA), Hsi-Wei Yen (ASIAA), Nagayoshi Ohashi (ASIAA), and the eDisk collaboration.

Presenter: Travis Thieme (ASIAA)

Observations of protostellar cores indicate high levels of magnetization that are enough to suppress the formation of protostellar disks. However, observations continue to detect large, rotationally supported disks around a growing number of young protostars. Non-ideal MHD effects are proposed as one way to allow these protostellar disks to form in magnetized environments. However, these effects are difficult to detect and quantify observationally. Cosmic-ray ionization is shown to impact the efficiency of non-ideal MHD effects through the ionization fraction within the protostellar envelope. This means, we can potentially use these quantities to indirectly understand the importance of non-ideal MHD effects. We have observed H13CO+ and DCO+ in 16 protostellar cores containing protostars with well-constrained protostellar disk radii from the eDisk ALMA large program to estimate the cosmic-ray ionization rate and ionization fraction, in order to compare and statistically assess the importance of non-ideal MHD during the formation of protostellar disks.