A New Limit on CMB Circular Polarization from SPIDER

• Published in: The Astrophysical Journal
• Main Authors: Nagy, JM, Ade, PAR, Amiri, M, Benton, SJ, Bergman, AS, Bihary, R, Bock, JJ, Bond, JR, Bryan, SA, Chiang, HC, Contaldi, CR, Dore, O, Duivenvoorden, AJ, Eriksen, HK, Farhang, M, Filippini, JP, Fissel, LM, Fraisse, AA, Freese, K, Galloway, M, Gambrel, AE, Gandilo, NN, Ganga, K, Gudmundsson, JE, Halpern, M, Hartley, J, Hasselfield, M, Hilton, G, Holmes, W, Hristov, VV, Huang, Z, Irwin, KD, Jones, WC, Kuo, CL, Kermish, ZD, Li, S, Mason, PV, Megerian, K, Moncelsi, L, Morford, TA, Netterfield, CB, Nolta, M, Padilla, IL, Racine, B, Rahlin, AS, Reintsema, C, Ruhl, JE, Runyan, MC, Ruud, TM, Shariff, JA, Soler, JD, Song, X, Trangsrud, A, Tucker, C, Tucker, RS, Turner, AD, Van Der List, JF, Weber, AC, Wehus, IK, Wiebe, DV, Young, EY
• Other Authors: Science and Technology Facilities Council (STFC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Astronomical Society 2017
• Subjects: Science & Technology; Physical Sciences; Astronomy & Astrophysics; cosmic background radiation; HALF-WAVE PLATE; MICROWAVE BACKGROUND ASTRONOMY; SUBMILLIMETER INSTRUMENTS; astro-ph.CO; astro-ph.IM; 0201 Astronomical And Space Sciences; 0305 Organic Chemistry; 0306 Physical Chemistry (Incl. Structural); Antarctic; Antarc*
• Online Access: http://hdl.handle.net/10044/1/52031; https://doi.org/10.3847/1538-4357/aa7cfd

We present a new upper limit on cosmic microwave background (CMB) circular polarization from the 2015 flight of Spider, a balloon-borne telescope designed to search for B-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the nonzero circular-to-linear polarization coupling of the half-wave plate polarization modulators, data from Spider's 2015 Antarctic flight provide a constraint on Stokes V at 95 and 150 GHz in the range $33\lt {\ell }\lt 307$. No other limits exist over this full range of angular scales, and Spider improves on the previous limit by several orders of magnitude, providing 95% C.L. constraints on ${\ell }({\ell }+1){C}_{{\ell }}^{{VV}}/(2\pi )$ ranging from 141 to 255 μK2 at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain even stronger constraints on circular polarization.