The Latest Constraints on Inflationary B-modes from the BICEP/Keck Telescopes

• Main Authors: Ade, P.A.R., Ahmed, Z., Amiri, M., Barkats, D., Thakur, R. Basu, Beck, D., Bischoff, C., Bock, J.J., Boenish, H., Bullock, E., Buza, V., Cheshire, J.R., Connors, J., Cornelison, J., Crumrine, M., Cukierman, A., Denison, E.V., Dierickx, M., Duband, L., Eiben, M., Fatigoni, S., Filippini, J.P., Fliescher, S., Giannakopoulos, C., Goeckner-Wald, N., Goldfinger, D.C., Grayson, J., Grimes, P., Halal, G., Hall, G., Halpern, M., Hand, E., Harrison, S., Henderson, S., Hildebrandt, S.R., Hilton, G.C., Hubmayr, J., Hui, H., Irwin, K.D., Kang, J., Karkare, K.S., Karpel, E., Kefeli, S., Kernasovskiy, S.A., Kovac, J.M., Kuo, C.L., Lau, K., Leitch, E.M., Lennox, A., Megerian, K.G., Minutolo, L., Moncelsi, L., Nakato, Y., Namikawa, T., Nguyen, H.T., O'Brient, R., Ogburn, R.W., Palladino, S., Petroff, M., Prouve, T., Pryke, C., Racine, B., Reintsema, C.D., Richter, S., Schillaci, A., Schmitt, B.L., Schwarz, R., Sheehy, C.D., Singari, B., Soliman, A., Germaine, T. St, Steinbach, B., Sudiwala, R.V., Teply, G.P., Thompson, K.L., Tolan, J.E., Tucker, C., Turner, A., Umilta, C., Verges, C., Vieregg, A.G., Wandui, A., Weber, A.C., Wiebe, D.V., Willmert, J., Wong, C.L., Wu, W.L.K., Yang, H., Yoon, K.W., Young, E., Yu, C., Zeng, L., Zhang, C., Zhang, S.
• Other Authors: Laboratoire des Cryoréfrigérateurs et Cryogénie Spatiale (LCCS), Département des Systèmes Basses Températures (DSBT ), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), BICEP/Keck
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2022
• Subjects: cosmic background radiation: polarization; gravitational radiation: primordial; cosmological model: dust; beam: polarization; BICEP; synchrotron; noise; satellite: Planck; B-mode; pole; thermal; galaxy; WMAP; inflation; cosmological model: parameter space; statistical analysis: confidence limit; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; Amundsen-Scott; South pole
• Online Access: https://hal.science/hal-03632701

International audience For the past decade, the BICEP/Keck collaboration has been operating a series of telescopes at the Amundsen-Scott South Pole Station measuring degree-scale $B$-mode polarization imprinted in the Cosmic Microwave Background (CMB) by primordial gravitational waves (PGWs). These telescopes are compact refracting polarimeters mapping about 2% of the sky, observing at a broad range of frequencies to account for the polarized foreground from Galactic synchrotron and thermal dust emission. Our latest publication "BK18" utilizes the data collected up to the 2018 observing season, in conjunction with the publicly available WMAP and Planck data, to constrain the tensor-to-scalar ratio $r$. It particularly includes (1) the 3-year BICEP3 data which is the current deepest CMB polarization map at the foreground-minimum 95 GHz; and (2) the Keck 220 GHz map with a higher signal-to-noise ratio on the dust foreground than the Planck 353 GHz map. We fit the auto- and cross-spectra of these maps to a multicomponent likelihood model ($\Lambda$CDM+dust+synchrotron+noise+$r$) and find it to be an adequate description of the data at the current noise level. The likelihood analysis yields $\sigma(r)=0.009$. The inference of $r$ from our baseline model is tightened to $r_{0.05}=0.014^{+0.010}_{-0.011}$ and $r_{0.05}<0.036$ at 95% confidence, meaning that the BICEP/Keck $B$-mode data is the most powerful existing dataset for the constraint of PGWs. The up-coming BICEP Array telescope is projected to reach $\sigma(r) \lesssim 0.003$ using data up to 2027.