Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session C10: Large-Scale Structure and Cosmic Microwave Background |
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Sponsoring Units: DAP Room: Sheraton Governor's Square 12 |
Saturday, April 13, 2019 1:30PM - 1:42PM |
C10.00001: Structure formation beyond ΛCDM Marilena Loverde The large-scale structure of our universe (the distribution of galaxies on very large-scales for instance) contains a wealth of information about the origin, evolution, and matter content of the universe. Extracting this information relies crucially on understanding how galaxies and other biased objects trace the large-scale matter distribution. In a universe such as our own, with both cold dark matter and massive neutrinos, or in alternative cosmologies with clustered quintessence, this problem is much more complicated. I will discuss new tools to study gravitational evolution in cosmologies with multiple fluids, novel signatures that have been identified, including a new probe of neutrino mass, and the broader implications for models of large-scale structure. |
Saturday, April 13, 2019 1:42PM - 1:54PM |
C10.00002: A More Direct Method for Studying the Cosmic Velocity Correlation Function Yuyu Wang, Sarah A Peery, Hume A Feldman, Richard Watkins We derive the estimators of the radial and transverse large-scale cosmic velocity field correlation functions, which allow direct comparisons with linear theory predictions and the full three-dimensional velocity correlation functions. We generate realistic simulated mock catalogues with both random and Local Group observers using the Outer Rim simulation suites. The comparison between simulations and CosmicFlows-3 reveals the effect of Local Group Motion on the cosmic velocity correlation functions and the bias of different observers. |
Saturday, April 13, 2019 1:54PM - 2:06PM |
C10.00003: Super-Sample Covariance in Future Weak Lensing Surveys Matthew C Digman, Christopher M Hirata, Joseph Mcewen Finite volume weak lensing surveys are contaminated by long wavelength density perturbations. Accurately forecasting parameter constraints for such surveys requires accurately taking into account the super-sample effects. If super-sample covariance is in fact a major component of the survey error budget, it may be necessary to investigate mitigation strategies. We present a Fisher Matrix based formalism and code for approximating the magnitude of super-sample covariance and effectiveness of mitigation strategies for realistic survey geometries. |
Saturday, April 13, 2019 2:06PM - 2:18PM |
C10.00004: Imprints of Primordial Non-Gaussianity on Gravitational Wave Spectrum Caner Unal Although Cosmic Microwave Background and Large Scale Structure probe the largest scales of our universe with ever increasing precision, our knowledge about the smaller scales is still very limited other than the bounds on Primordial Black Holes. We show that the statistical properties of the small scale quantum fluctuations can be probed via the stochastic gravitational wave background, which is induced as the scalar modes re-enter the horizon. We found that even if scalar curvature fluctuations have a subdominant non-Gaussian component, these non-Gaussian perturbations can source a dominant portion of the induced GWs. Moreover, the GWs sourced by non-Gaussian scalar fluctuations peaks at a higher frequency and this can result in distinctive observational signatures. If the induced GW background is detected, but not the signatures arising from the non-Gaussian component, this translates into stringent bounds on non-Gaussianity depending on the amplitude of the GW signal. |
Saturday, April 13, 2019 2:18PM - 2:30PM |
C10.00005: Primordial Black Hole Abundances from Peaks Theory Jolyon K Bloomfield Given the black hole masses observed by LIGO as well as the continued possibility of explaining all of dark matter, there has been a recent renewed interest in primordial black holes (PBHs). In order to understand such phenomena, we need an accurate calculation of the expected abundance of PBHs from inflationary theory. Present computations of the mass spectrum and number density rely on two dubious "rules of thumb" to determine whether or not a primordial perturbation will undergo gravitational collapse. These approximations contribute significant uncertainty to current results, to the extent that most authors do not even estimate their errors. In this presentation, we describe a new method for computing PBH abundances using a combination of peaks theory, numerical relativity simulations and stochastic integration. We present proof of principle results for a simple hybrid inflation model. While computationally intensive, a rigorous error analysis of our method yields 5-10% error bars, improving on previous calculations by orders of magnitude. |
Saturday, April 13, 2019 2:30PM - 2:42PM |
C10.00006: Status of the POLARBEAR-2a CMB Telescope John Groh The Simons Array consists of 3 telescopes (POLARBEAR-2a, -2b, and -2c) designed to observe the Cosmic Microwave Background at frequencies between 75 and 300 GHz from an altitude of 5190 m atop the Chajnantor Plateau in the Chilean Atacama desert. Each telescope is an off-axis Gregorian designed to be sensitive to a large dynamic range of angular scales on the sky, enabling the study of both the lensing and the potential primordial B-mode polarization signals. Three cryogenic lenses and an aperture stop image a 4.5 degree field of view onto each focal plane, and continuously rotating half-wave plates modulate the polarization signal to mitigate sensitivity degradation at large angular scales. The Simons Array will contain 5691 dichroic polarization-sensitive lenslet-coupled planar antennas, each connected to four transition-edge sensor bolometers, cooled to operating temperatures below 300 mK. The detectors are read out with frequency-division multiplexing electronics operating in the 1.5 to 4.5 MHz band with a multiplexing factor of 40. POLARBEAR-2a, which has observation bands centered at 90 and 150 GHz, was deployed and achieved first light in December 2018. In this talk, I will present the current status of POLARBEAR-2a and summarize its initial on-sky performance.
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Saturday, April 13, 2019 2:42PM - 2:54PM |
C10.00007: Study of the Cross Correlation between Cosmic Microwave Background Polarization Lensing from POLARBEAR and Cosmic Shear from Subaru Hyper Suprime-Cam Yuji Chinone POLARBEAR is a cosmic microwave background (CMB) polarization experiment in the Atacama desert in Chile. The science goals are to characterize the B-mode signal from gravitational lensing, as well as do a deep search for B-mode signal created by primordial gravitational waves. POLARBEAR started observations in 2012, and has published a series of results from its first and second seasons, including the first measurement of a non-zero lensing B-mode auto-power spectrum. HSC is the wide-field optical/near infrared imager mounted at the prime focus of the Subaru Telescope at the summit of Maunakea. HSC offers the wide field-of-view, superb image quality, and fast and deep imaging capability thanks to the large primary mirror, which makes it one of the best instruments to conduct a weak lensing survey. HSC started a wide, deep galaxy imaging survey from 2014. The cross correlation provides additional tomographic information on the large scale structure and is less sensitive to systematics. We present the status of the cross correlation measurement between CMB polarization lensing and cosmic shear from POLARBEAR and Subaru HSC data. These data are among the deepest maps of the lensing field to date, enabling the measurement of the cross power without the CMB temperature fluctuation.
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Saturday, April 13, 2019 2:54PM - 3:06PM |
C10.00008: Modulations of the CMB Daniel Grin Cosmic microwave background (CMB) anisotropies are Gaussian and isotropic at linear order. The presence of long wavelength modulating fields, however, can introduce non-Gaussianity and statistical anisotropy in the CMB. There are discrepancies between the observed CMB lensing signal and theoretical expectations. We explore the possibility that compensated isocurvature perturbations or spatial fluctuations in the fine-structure constant could solve this problem. The imprint of both these possibilities on CMB statistics is computed. Current data are used to probe these models, forecasts are made for the sensitivity of upcoming efforts like CMB Stage IV , and a variety of other theoretical considerations are explored. |
Saturday, April 13, 2019 3:06PM - 3:18PM |
C10.00009: CCAT-prime: Cosmology with A Six-meter Submillimeter Telescope at Cerro Chajnantor Steve Choi, the CCAT-prime Collaboration CCAT-prime is a new 6 m crossed Dragone telescope designed to measure the Sunyaev-Zel’dovich effects of galaxy clusters, the CMB polarization and foregrounds, and the [CII] emission from the Epoch of Reionization. CCAT-prime will observe from a 5600 m altitude site on Cerro Chajnantor in the Atacama Desert. The novel optical design of the telescope combined with a high surface accuracy, and the exceptional atmospheric conditions of the site will enable sensitive broadband, polarimetric, and spectroscopic surveys at sub-mm to mm wavelengths. Prime-Cam, the first light instrument for CCAT-prime, consists of a large cryostat that can house seven individual instrument modules that use multichroic transition edge sensors, kinetic inductance detectors, and Fabry-Perot interferometers. Prime-Cam is currently being developed, and the telescope is under construction to achieve first light in 2021. CCAT-prime is also a potential telescope platform for the CMB Stage-IV observations. |
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