A millimeter-wave Galactic plane survey with the bicep polarimeter

Bierman, E. M., Matsumura, T., Dowell, C. D., Keating, B. G., Ade, Peter A. R. ORCID: https://orcid.org/0000-0002-5127-0401, Barkats, D., Barron, D., Battle, J. O., Bock, J. J., Chiang, H. C., Culverhouse, T. L., Duband, L., Hivon, E. F., Holzapfel, W. L., Hristov, V. V., Kaufman, J. P., Kovac, J. M., Kuo, C. L., Lange, A. E., Leitch, E. M., Mason, P. V., Miller, N. J., Nguyen, H. T., Pryke, C., Richter, S., Rocha, G. M., Sheehy, C., Takahashi, Y. D. and Yoon, K. W. 2011. A millimeter-wave Galactic plane survey with the bicep polarimeter. The Astrophysical Journal 741 (2) , 81. 10.1088/0004-637X/741/2/81

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Abstract

In order to study inflationary cosmology and the Milky Way Galaxy's composition and magnetic field structure, Stokes I, Q, and U maps of the Galactic plane covering the Galactic longitude range 260° < ℓ < 340° in three atmospheric transmission windows centered on 100, 150, and 220 GHz are presented. The maps sample an optical depth 1 AV 30, and are consistent with previous characterizations of the Galactic millimeter-wave frequency spectrum and the large-scale magnetic field structure permeating the interstellar medium. The polarization angles in all three bands are generally perpendicular to those measured by starlight polarimetry as expected and show changes in the structure of the Galactic magnetic field on the scale of 60°. The frequency spectrum of degree-scale Galactic emission is plotted between 23 and 220 GHz (including WMAP data) and is fit to a two-component (synchrotron and dust) model showing that the higher frequency BICEP data are necessary to tightly constrain the amplitude and spectral index of Galactic dust. Polarized emission is detected over the entire region within two degrees of the Galactic plane, indicating the large-scale magnetic field is oriented parallel to the plane of the Galaxy. A trend of decreasing polarization fraction with increasing total intensity is observed, ruling out the simplest model of a constant Galactic magnetic field orientation along the line of sight in the Galactic plane. A generally increasing trend of polarization fraction with electromagnetic frequency is found, varying from 0.5%-1.5% at frequencies below 50 GHz to 2.5%-3.5% above 90 GHz. The effort to extend the capabilities of BICEP by installing 220 GHz band hardware is described along with analysis of the new band.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	cosmology: observations; Galaxy: structure; instrumentation: polarimeters; radio continuum: ISM; submillimeter: diffuse background; submillimeter: ISM
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0004-637X/ (accessed 21/02/2014).
Publisher:	Institute of Physics
ISSN:	0004-637X
Date of First Compliant Deposit:	30 March 2016
Last Modified:	07 May 2023 05:32
URI:	https://orca.cardiff.ac.uk/id/eprint/34585

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