A Measurement of the Cosmic Microwave Background B -mode Polarization Power Spectrum at Subdegree Scales from Two Years of polarbear Data

The POLARBEAR Collaboration, P. A. R. Ade, M. Aguilar, Y. Akiba, K. Arnold, C. Baccigalupi, D. Barron, D. Beck, F. Bianchini, D. Boettger, J. Borrill, S. Chapman, Y. Chinone, K. Crowley, A. Cukierman, R. Dünner, M. Dobbs, A. Ducout, T. Elleflot, J. Errard, G. Fabbian, S. M. Feeney, C. Feng, T. Fujino, N. Galitzki, A. Gilbert, N. Goeckner-Wald, J. C. Groh, G. Hall, N. Halverson, T. Hamada, M. Hasegawa, M. Hazumi, C. A. Hill, L. Howe, Y. Inoue, G. Jaehnig, A. H. Jaffe, O. Jeong, D. Kaneko, N. Katayama, B. Keating, R. Keskitalo, T. Kisner, N. Krachmalnicoff, A. Kusaka, M. Le Jeune, A. T. Lee, E. M. Leitch, D. Leon, E. Linder, L. Lowry, F. Matsuda, T. Matsumura, Y. Minami, J. Montgomery, M. Navaroli, H. Nishino, H. Paar, J. Peloton, A. T. P. Pham, D. Poletti, G. Puglisi, C. L. Reichardt, P. L. Richards, C. Ross, Y. Segawa, B. D. Sherwin, M. Silva-Feaver, P. Siritanasak, N. Stebor, R. Stompor, A. Suzuki, O. Tajima, S. Takakura, S. Takatori, D. Tanabe, G. P. Teply, T. Tomaru, C. Tucker, N. Whitehorn, A. Zahn

2017/01/01

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Abstract

We report an improved measurement of the cosmic microwave background B -mode polarization power spectrum with the Polarbear experiment at 150 GHz. By adding new data collected during the second season of observations (2013–2014) to re-analyzed data from the first season (2012–2013), we have reduced twofold the band-power uncertainties. The band powers are reported over angular multipoles ##IMG## [http://ej.iop.org/images/0004-637X/848/2/121/apjaa8e9fieqn1.gif] $500łeqslant ell łeqslant 2100$ , where the dominant B -mode signal is expected to be due to the gravitational lensing of E -modes. We reject the null hypothesis of no B -mode polarization at a confidence of 3.1 σ including both statistical and systematic uncertainties. We test the consistency of the measured B -modes with the Λ Cold Dark Matter (ΛCDM) framework by fitting for a single lensing amplitude parameter A L relative to the Planck 2015 best-fit model prediction. We obtain ##IMG## [http://ej.iop.org/images/0004-637X/848/2/121/apjaa8e9fieqn2.gif] $A_L=0.60_-0.24^+0.26(mathrmstat)_-0.04^+0.00(mathrminst)$ ± 0.14(foreground) ± 0.04(multi), where ##IMG## [http://ej.iop.org/images/0004-637X/848/2/121/apjaa8e9fieqn3.gif] $A_L=1$ is the fiducial ΛCDM value.

Type

Journal article

Publication

The Astrophysical Journal