Comparing Submillimeter Polarized Emission with Near-infrared Polarization of Background Stars for the Vela C Molecular Cloud

Fabio P. Santos, Peter A.R. Ade, Francesco E. Angilè, Peter Ashton, Steven J. Benton, Mark J. Devlin, Bradley Dober, Laura M. Fissel, Yasuo Fukui, Nicholas Galitzki, Natalie N. Gandilo, Jeffrey Klein, Andrei L. Korotkov, Zhi Yun Li, Peter G. Martin, Tristan G. Matthews, Lorenzo Moncelsi, Fumitaka Nakamura, Calvin B. Netterfield, Giles NovakEnzo Pascale, Frédérick Poidevin, Giorgio Savini, Douglas Scott, Jamil A. Shariff, Juan Diego Soler, Nicholas E. Thomas, Carole E. Tucker, Gregory S. Tucker, Derek Ward-Thompson

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

We present a large-scale combination of near-infrared (near-IR) interstellar polarization data from background starlight with polarized emission data at submillimeter wavelengths for the Vela C molecular cloud. The near-IR data consist of more than 6700 detections probing a range of visual extinctions between 2 and 20 mag in and around the cloud. The submillimeter data were collected in Antarctica by the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry. This is the first direct combination of near-IR and submillimeter polarization data for a molecular cloudaimed at measuring the "polarization efficiency ratio" (Reff), a quantity that is expected to depend only on grainintrinsic physical properties. It is defined as p500 (pI τv ), where p500 and pI are polarization fractions at 500 mm and the I band, respectively, and τv is the optical depth. To ensure that the same column density of material is producing both polarization from emission and from extinction, we conducted a careful selection of near-background stars using 2MASS, Herschel, and Planck data. This selection excludes objects contaminated by the Galactic diffuse background material as well as objects located in the foreground. Accounting for statistical and systematic uncertainties, we estimate an average Reff value of 2.4 ± 0.8, which can be used to test the predictions of dust grain models designed for molecular clouds when such predictions become available. The ratio Reff appears to be relatively flat as a function of the cloud depth for the range of visual extinctions probed.

Original languageEnglish (US)
Article number161
JournalAstrophysical Journal
Volume837
Issue number2
DOIs
StatePublished - Mar 10 2017

Keywords

  • ISM: individual objects (Vela C molecular cloud)
  • ISM: magnetic fields
  • dust, extinction
  • techniques: polarimetric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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