Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session C8: CMB I |
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Sponsoring Units: DAP Chair: Nils Halverson, University of Colorado at Boulder Room: Governor's Square 10 |
Saturday, April 13, 2013 1:30PM - 1:42PM |
C8.00001: Precision Measurements of the Cosmic Microwave Background Polarization from the POLARBEAR experiment Bryan Steinbach We present status and results from the first season of observations of the POLARBEAR experiment. POLARBEAR is measuring the Cosmic Microwave Background (CMB) polarization anisotropies to constrain neutrino mass, inflation, dark energy, and cosmic birefringence. Since early 2012 POLARBEAR has been performing a deep search in 30 square degrees of sky to find odd parity B modes in the CMB polarization anisotropies induced by gravitational lensing. POLARBEAR observes with 1000 single mode 150GHz detectors with 3.5' FWHM beams from an off axis Gregorian Dragone 3m telescope in the Atacama Desert in Chile. [Preview Abstract] |
Saturday, April 13, 2013 1:42PM - 1:54PM |
C8.00002: ABSTRACT HAS BEEN MOVED TO R8.00009 |
Saturday, April 13, 2013 1:54PM - 2:06PM |
C8.00003: The Keck Array CMB polarimeter overview and status Zachary Staniszewski The Keck Array is a CMB polarimeter observing at the geographic South Pole for its third season. The instrument is optimized to measure the inflationary polarization signal in the cosmic microwave background. We use the minimum necessary aperture to resolve degree-scale polarization features. This allows us to simultaneously deploy five compact receivers to maximize the number of detectors and sensitivity. We have upgraded the instrument with new detector arrays for improved instrumental sensitivity for our third year of observation. I will discuss recent upgrades and instrument characterization, and show progress toward new cosmological constraints. [Preview Abstract] |
Saturday, April 13, 2013 2:06PM - 2:18PM |
C8.00004: The Atacama B-mode Search: Status and Prospect Akito Kusaka The Atacama B-mode Search (ABS) experiment is a 145 GHz polarimeter designed to measure the B-mode polarization of the Cosmic Microwave Background (CMB) at degre angular scales. In January 2012, ABS has deployed 240 polarimeters employing transition-edge sensor (TES) bolometers. ABS has unique advantages for the measurement of B modes. This includes a continuously rotating half-wave plate that provides fast and clean modulation, as well as systematically clean optics that consist of a cryogenic side-fed Dragone telescope and feedhorn coupled TES polarimeters. In this talk, we will present the status and prospect of ABS. [Preview Abstract] |
Saturday, April 13, 2013 2:18PM - 2:30PM |
C8.00005: The physical origin of constraints on cosmological parameters from cosmic microwave background measurements Zhen Hou The angular power spectrum of the cosmic microwave background (CMB) has been precisely measured on different scales recently by WMAP, SPT and ACT, and will be greatly improved by the Planck satellite by the time of the meeting. The CMB power spectrum is crucial to the constraints on cosmological parameters, but in a very indirect and model-dependent way. It is important to understand the physics of how the cosmological parameters are constrained given these new CMB datasets instead of treating the modern Boltzmann codes as a black box. I will present how the LCDM parameters are constrained, as well as various parameters in extensions to the LCDM model, including curvature ($\Omega_k$), the primordial helium abundance ($Y_p$), the effective number of relativistic neutrino species ($N_{\rm eff}$) and the mass of the neutrinos ($\sum m_\nu$). I will show that the constraints on these extensions are from different physical processes at different epochs of the evolution of the Universe. [Preview Abstract] |
Saturday, April 13, 2013 2:30PM - 2:42PM |
C8.00006: ABSTRACT WITHDRAWN |
Saturday, April 13, 2013 2:42PM - 2:54PM |
C8.00007: Constraints from Planck and Other Experiments on Big Bang Nucleosynthesis Marius Millea The Cosmic Microwave Background (CMB) is our most powerful tool for probing cosmological parameters. By the time of the meeting, results from Planck will be released which will provide the tightest constraints obtained from temperature anisotropies to-date on the physics of Big Bang Nucleosynthesis (BBN). We will present these constraints from Planck on BBN parameters like the baryon-to-photon ratio, the number of neutrino species, and the primordial helium fraction, and compare these to constraints from other sources, for example more direct measurements of primordial helium and deuterium. These comparisons provide a powerful tool to test the validity of the standard BBN model. Finally, we forecast the improvement in constraints expected from future measurements of CMB polarization. [Preview Abstract] |
Saturday, April 13, 2013 2:54PM - 3:06PM |
C8.00008: Constraints on Tensor-to-scalar Ratio for Planck Mission King Lau, Jiayu Tang, Ming Chung Chu One of the main goals of modern CMB missions is to measure the tensor-to-scalar ratio $r$ accurately to constrain inflation models. Due to the ignorance of the reionization history $X_{e}(z)$, this analysis is usually done by assuming an instantaneous reionization $X_{e}(z)$ occurring at $z\sim10$. Moreover, due to strong mixing of B-mode and E-mode polarizations in cut-sky measurements, applying the simple $f_{sky}$ modification on full-sky forecast would not give satisfactory results. In this work, we make a forecast of the constraints on $r$ for the Planck mission taking into account the general reionization scenario and cut-sky. We also study the degeneracy caused by $r$ and $X_{e}(z)$ on B-mode polarization. Our results show that by applying N-point interpolation analysis on reionization history, it can correct the bias induced by instantaneous reionization assumption and the best fit of $r$ is constrained within $5\%$ error level by including both temperature and polarization correlation in likelihood, if the true value of $r$ is 0.1. [Preview Abstract] |
Saturday, April 13, 2013 3:06PM - 3:18PM |
C8.00009: Planck component separation with Commander Ingunn Kathrine Wehus I will give a brief overview of the Bayesian component separation technique used by Planck to derive astrophysical foreground components. Starting from an explicit parametric model of the data and corresponding priors, we use a statistical technique called Gibbs sampling to map out the full joint posterior distribution given full-sky multi-frequency observations. This process leads to a set of well-defined component maps with associated uncertainties and goodness-of-fit statistics. For Planck alone, we derive maps of the CMB, CO, thermal dust and a joint low-frequency component (synchrotron, free-free and spinning dust), while when including external data (WMAP, Haslam etc.) even more detailed models can be considered. I will comment on how these new products compare with previously published results. [Preview Abstract] |
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