CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

CMB-S4---the next-generation ground-based cosmic microwave background (CMB) experiment---is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semi-analytic projection tool, targeted explicitly towards optimizing constraints on the tensor-to-scalar ratio, $r$, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2--3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments given a desired scientific goal. To form a closed-loop process, we couple this semi-analytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for $r > 0.003$ at greater than $5\sigma$, or, in the absence of a detection, of reaching an upper limit of $r < 0.001$ at $95\%$ CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note: text overlap with arXiv:1907.0447

CMB-S4

We describe the stage 4 cosmic microwave background ground-based experiment CMB-S4

CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

Abstract: CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL

Interactions of galactic cosmic rays with the lunar surface

Ph.D. University of Hawaii at Manoa 2014.Includes bibliographical references.This dissertation is focused on improving understanding of the composition and structure of the Moon's crust and the processes that have affected it over its history. This is accomplished through integrating remote sensing datasets with models of modifying processes such as basin-forming impacts and galactic cosmic ray radiation. I focus on two areas of active study for the Moon: the nature of the mafic component of the highlands crust, and the unique nature of the Moon's polar regions. The first part of this dissertation integrates three remote sensing data sets: 1) mineral maps derived from ultraviolet-visible spectroscopy from the Clementine mission, 2) neutron counts from the lunar surface from the Lunar Prospector neutron spectrometer, and 3) elemental abundances from the Lunar Prospector gamma ray spectrometer. Systematic discrepancies between the three datasets are identified and resolved, resulting in new abundance maps of the major lunar minerals (olivine, clinopyroxene, orthopyroxene, plagioclase, and ilmenite) and an associated map of magnesium number for the mafic minerals. The second part of this dissertation employs the new mineral maps as constraints on mixing models. The mixing models assess contributions to the current lunar highlands crust of primary magma ocean anorthosites, later igneous products, and ultramafic mantle material excavated by large basins. We conclude that the magma ocean likely did not predominately produce anorthosites containing 15 vol% mafic minerals, and that the combined contribution to the highlands crust of ultramafic mantle material excavated by large basins and post-magma ocean igneous activity is between 15 and 45 vol%. The mixing models also support the conclusion of Weiczorek and Phillips (1999) that the excavation cavities of the largest lunar basins had depth-to-diameter ratios shallower than 1/10 (ratios between 0.03 and 0.07 are consistent with our mixing models). The final part of this dissertation uses the radiation transport code MCNPX 2.6.0 to model the radiation dose from galactic cosmic rays absorbed at different depths in the lunar regolith. We conclude that if simple ices are present in polar cold traps, they could have accumulated radiation doses equivalent to those used in experiments to stimulate synthesis of complex organic species

Detection of Intact Lava Tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder

Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon\u27s composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.00°N, 301.85–304.01°E around the MHH, and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille

Detection of Intact Lava Tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder

Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon\u27s composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.00°N, 301.85–304.01°E around the MHH, and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille

CCAT-prime Collaboration: Science Goals and Forecasts with Prime-Cam on the Fred Young Submillimeter Telescope

We present a detailed overview of the science goals and predictions for the Prime-Cam direct-detection camera-spectrometer being constructed by the CCAT-prime collaboration for dedicated use on the Fred Young Submillimeter Telescope (FYST). The FYST is a wide-field, 6 m aperture submillimeter telescope being built (first light in late 2023) by an international consortium of institutions led by Cornell University and sited at more than 5600 m on Cerro Chajnantor in northern Chile. Prime-Cam is one of two instruments planned for FYST and will provide unprecedented spectroscopic and broadband measurement capabilities to address important astrophysical questions ranging from Big Bang cosmology through reionization and the formation of the first galaxies to star formation within our own Milky Way. Prime-Cam on the FYST will have a mapping speed that is over 10 times greater than existing and near-term facilities for high-redshift science and broadband polarimetric imaging at frequencies above 300 GHz. We describe details of the science program enabled by this system and our preliminary survey strategies