Relative Alignment between the Magnetic Field and Molecular Gas Structure in the Vela C Giant Molecular Cloud Using Low- and High-density Tracers

• Published in: The Astrophysical Journal
• Main Authors: Fissel, Laura M., Ade, Peter A. R., Angilè, Francesco E., Ashton, Peter, Benton, Steven J., Chen, Che-Yu, Cunningham, Maria, Devlin, Mark J., Dober, Bradley, Friesen, Rachel, Fukui, Yasuo, Galitzki, Nicholas, Gandilo, Natalie N., Goodman, Alyssa, Green, Claire-Elise, Jones, Paul, Klein, Jeffrey, King, Patrick, Korotkov, Andrei L., Li, Zhi-Yun, Lowe, Vicki, Martin, Peter G., Matthews, Tristan G., Moncelsi, Lorenzo, Nakamura, Fumitaka, Netterfield, Calvin B., Newmark, Amanda, Novak, Giles, Pascale, Enzo, Poidevin, Frédérick, Santos, Fabio P., Savini, Giorgio, Scott, Douglas, Shariff, Jamil A., Soler, Juan D., Thomas, Nicholas E., Tucker, Carole E., Tucker, Gregory S., Ward-Thompson, Derek, Zucker, Catherine
• Other Authors: Univ Arizona, Arizona Radio Observ
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP PUBLISHING LTD 2019
• Subjects: dust; extinction; ISM: individual objects (Vela C); ISM: magnetic fields; ISM: molecules; molecular data; Canada; National Science Foundation Office of Polar Programs
• Online Access: http://hdl.handle.net/10150/633535; https://doi.org/10.3847/1538-4357/ab1eb0

We compare the magnetic field orientation for the young giant molecular cloud Vela C inferred from 500 mu m polarization maps made with the BLASTPol balloon-borne polarimeter to the orientation of structures in the integrated line emission maps from Mopra observations. Averaging over the entire cloud we find that elongated structures in integrated line-intensity or zeroth-moment maps, for low-density tracers such as (CO)-C-12 and (CO)-C-13 J -> 1 - 0, are statistically more likely to align parallel to the magnetic field, while intermediate- or high-density tracers show (on average) a tendency for alignment perpendicular to the magnetic field. This observation agrees with previous studies of the change in relative orientation with column density in Vela C, and supports a model where the magnetic field is strong enough to have influenced the formation of dense gas structures within Vela C. The transition from parallel to no preferred/perpendicular orientation appears to occur between the densities traced by (CO)-C-13 and by (CO)-O-18 J -> 1 - 0. Using RADEX radiative transfer models to estimate the characteristic number density traced by each molecular line, we find that the transition occurs at a molecular hydrogen number density of approximately 10(3) cm(-3). We also see that the Centre Ridge (the highest column density and most active star-forming region within Vela C) appears to have a transition at a lower number density, suggesting that this may depend on the evolutionary state of the cloud. NASA [NNX13AE50G, 80NSSC18K0481, NAG5-12785, NAG5-13301, NNGO-6GI11G, NNX0-9AB98G]; Illinois Space Grant Consortium; Canadian Space Agency; Leverhulme Trust [F/00 407/BN]; Natural Sciences and Engineering Research Council of Canada; Canada Foundation for Innovation; Ontario Innovation Trust; US National Science Foundation Office of Polar Programs; Australian Government; European Research Council (ERC) under the Horizon 2020 Framework Program [CSF-648505]; European Commission under the Marie Sklodowska-Curie Actions within the H2020 program [658499 PolAME H2020-MSCA-IF-2014] This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [e-mail].