Max E. Tegmark - US grants

Tegmark
AST-0071213

Progress in detector, space and computer technology has triggered an avalanche of high-quality
cosmological data from ongoing and upcoming experiments. However, the accuracy of present and upcoming measurements of cosmological parameters is limited by real-world headaches such as parameter degeneracies, microwave foregrounds, galaxy bias, and a long list of possible systematic errors. To take full advantage of the avalanche of great new data, the new higher level of ambition for precision cosmology must therefore be matched by a corresponding improvement in our understanding of these murky and often unpleasant issues. This is the purpose of the present proposal: to apply a number of recently developed techniques to currently available data sets to address a range of such real-world issues.

The proposed work has the following main objectives: using the results of measurements of the Cosmic Microwave Background radiation field, Large Scale Structure surveys, and the recent SNIa surveys,:
1. To compute joint constraints of all relevant cosmological constraints on the following ten cosmological parameters : Baryon density, Cold dark matter density , Massive neutrino density , Contribution from vacuum energy , Reionization optical depth, Spatial curvature k , Spectral index of scalar fluctuations, Spectral index of gravity waves, Primordial fluctuation amplitude, and the Relative amplitude of gravity waves, and to study the robustness of these results with respect to problems with the various input data sets.
2. To compare overlapping CMB experiments to assess the levels of systematic problems, relative calibration errors and frequency-dependent foreground contamination, to combine consistent data sets into a single larger foreground-cleaned map and to compute its power spectrum with uncorrelated error bars.
3. To reanalyze a number of key galaxy redshift surveys in a uniform way using the new Schlegel,
Davis & Finkbeiner extinction maps and a matrix-based analysis technique that allows an
exact calculation of window functions, including the so-called integral constraint, as well as
the production of a power spectrum with uncorrelated error bars. This analysis will also
include the complications of scale-dependent stochastic bias, using redshift-space distortions.
Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).
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AST- 0134999
Max Tegmark

Dr. Tegmark is awarded funds at the University of Pennsylvania to refine current cosmological models. These models will make use of existing and new data that include observations of the cosmic microwave background, galaxy surveys, supernova surveys, and others. With global analysis of these data, he expects to be able to address the natures of dark matter and dark energy beyond just their current density, the behavior of gravity on large scales, the nature of the early universe, and the history of structure formation in the universe.

The PI will also initiate a high-school outreach program in the Philadelphia school district. The PI and graduate students will present lectures and demonstrations on cosmology to high-school science classes, hoping to recruit students into existing programs that typically reach only the affluent suburbs. In addition to his regular course development, the PI will also enhance his existing website on cosmology to contain a comprehensible introduction to state-of-the-art cosmology research in lay terms, intended for the general public.

AST-0607597
de Oliveira-Costa

Two of the most promising probes of cosmology are polarization maps of the cosmic microwave background (CMB), and three-dimensional tomographic maps reconstructing the 21-cm emission from neutral hydrogen at high redshifts in the early Universe. These measurements have the potential to constrain the nature of dark matter, dark energy, the early Universe, and the end of the cosmic dark ages. However, these constraints will only be as good as our understanding of Galactic foreground contamination. This project is a comprehensive study of polarized and unpolarized Galactic emission from 50 MHz to 500 GHz, combining available data with simulations. This will be useful both for foreground-cleaning current measurements and for optimizing the design of future experiments. Publicly available products will include improved foreground-cleaned unpolarized and polarized CMB maps, with well-quantified residuals, realistic 21cm foreground data cubes, cleaning algorithms and software.

As well as strengthening the foundation for a vast array of theoretical and phenomenological work, this research will not only train students, but also afford ample opportunities for public talks and other educational outreach. The origin, evolution and fate of the Universe continue to captivate the imagination of the general public.

AST-0708534
Tegmark

Recent years have seen spectacular progress in cosmology. This project will continue research in cosmic phenomenology, developing improved analysis methods and using them to sharpen cosmological constraints and theoretical understanding. Better data from current and upcoming experiments will be used to improve knowledge about neutrinos, dark matter, dark energy and the early Universe. The key components of this research are: 1) cosmology with galaxy clustering, including using smaller scale information than before, for degeneracy breaking and consistency testing; 2) illuminating the "dark ages" by developing information theory based techniques for 21 cm tomography data analysis, for fast yet nearly lossless extraction of cosmological information, concerning both the epoch of reionization and fundamental physics; 3) theoretical and phenomenological calculations to strengthen the link between observations and the underlying theories and their free parameters. A common theme is the use of information theory based techniques to tackle the mathematical and statistical challenges posed by massive data sets, particularly for managing and modeling uncertainty.

Along with strengthening the foundation for the emerging standard model of cosmology, this research will develop broadly useful data and tools, which will promptly be made publicly available. The project trains students, and offers ample opportunities for public talks and other educational outreach. The origin, evolution and fate of the universe have long captivated the imagination of the general public, allowing for active work in both formal and informal public outreach.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

This project involves experimental and theoretical studies geared toward detection and interpretation of 21-cm neutral hydrogen signatures of the Epoch of Reionization (EOR). The theoretical part of the proposal will quantify how accurately future 21 cm tomography data can constrain the cosmic expansion history and dark energy, the cosmic clustering history and dark matter/neutrino masses, primordial non-Gaussianity, and inflation. The experimental part will study a new concept in this field, a radio telescope with elements on a regular grid that can cut computing requirements significantly by using fast Fourier transforms. This is a highly cost-effective design relative to traditional radio arrays, and the award will fund continued development of a prototype telescope array.

Broader impacts of this proposal include training of underrepresented graduate students, undergraduate student projects, and public outreach featuring high school lectures, popular talks, and articles on cosmology.

Mapping neutral hydrogen throughout our Universe via its redshifted 21 cm line offers a unique opportunity to probe the cosmic "dark ages" and the formation of the first luminous objects. Moreover, because it can map a much larger volume of our Universe, it has the potential to overtake the cosmic microwave background as the most sensitive cosmological probe of the epoch of reionization, inflation, dark matter, dark energy, and neutrino masses. This potential has stimulated growing community interest, reflected by the Hydrogen Epoch of Reionization Arrays (HERA) effort and the Astro2010 Decadal Review, with initial focus of technology development and demonstration.

The goal of this research is to develop a digital radio interferometer back-end with a novel architecture, test it with a 64 dual-polarization antenna array, and generate calibrated foreground maps covering much of the sky at 110-190 MHz, all of which will help further HERA development. By exploiting a hierarchical antenna grid and 4-dimensional Fast Fourier Transforms (FFT), the proposed correlator cost scales as N log N with the number of independent elements rather than as N^2 like other HERA pathfinder experiments, allowing significant cost savings/collecting area increases down the road. Also, N independent sky beams are imaged simultaneously, improving mapping sensitivity. By exploiting the massive baseline redundancy in this antenna grid, gain and phase calibration for all antennas can be made significantly more accurate and fully automated. This can in turn produce more accurate modeling of the synthesized and primary beams, which has been shown to improve the quality of the foreground modeling and removal which is so crucial to 21 cm cosmology.

The proposed MIT Epoch of Reionization (MITEoR) instrument will be built on the NSF-funded open-source CASPER FPGA hardware platform, ensuring that the technology and instrumentation that we develop can be used by the worldwide community and incorporated into future HERA instruments, regardless of their antenna design and frequency range. In particular, most current visions for massive future radio arrays (like HERA-II and SKA) involve large compact cores, for which the technology that we will develop arguably offers both the lowest correlator cost and the most accurate calibration.

Along with strengthening the foundation for the emerging standard model of cosmology, this research should develop broadly useful technology, algorithms and tools. The hierarchical FFT imaging idea is also relevant to other areas, e.g., the search for radio transients and perhaps microwave background polarization.

As in the past, such products of our work useful to the broader community (data, algorithms, software, etc.) will promptly be made publicly available. The proposed research will also provide valuable student training. Furthermore, since the origin, evolution and fate of the universe have captivated the imagination of the general public, our group will continue to be very engaged in both formal and informal public outreach activities on this topic.

How does the brain compute? Understanding this process could lead to many advances in science and technology. The Boyden, Flavell, Barabasi, and Tegmark groups propose to examine how the cells within the brain of a simple animal work together to generate the computations that underlie behavior. The teams will study C. elegans, a small worm with just a few hundred neurons, yet capable of learning and adaptive behavior in complex real-world environments.  The teams will apply new technologies to measure and control the neural circuits of C. elegans, in order to investigate how they works. The project will also generate new mathematical tools to analyze the data that is collected - tools that could help analyze how the brain goes wrong in disorders such as Parkinson's or Alzheimer's. Using the data acquired, the project will reveal how brain circuits compute, which could inspire new algorithms for machine learning and computer information processing. These in turn could have broad impact on economic prosperity as well as in advancing human quality of life.

The Boyden, Flavell, Barabasi, and Tegmark groups will launch a novel integrative endeavor to reveal how entire nervous systems - from sensory input neurons, to motor output neurons, and including the networks that underlie learning, decision making, and other processes - work together as emergent wholes to generate the computations that underlie behavior. They will utilize C. elegans, with just 302 neurons, yet capable of learning and adaptive behavior in complex real-world environments.  They will optimize and deploy novel technologies, including a new fluorescent voltage indicator for C. elegans, and a method for 3-D visualization of entire nervous systems with molecular information via physical expansion by up to 10,000 fold in volume. They will record neural and behavioral dynamics, imaging the activity of neurons throughout entire brains and even entire nervous systems of freely moving as well as fictively behaving C. elegans engaged in complex decision-making tasks, or forming new memories. They will then use expansion microscopy to map the structure and molecular profiles of entire individual nervous systems. They will analyze the resultant network structures to determine how individual variation in these features connect to details of an individual's behavior, and make mathematical models of the relevant neural circuits capable of predicting how the nervous system would respond in complex contexts. The outcome of their work will yield radical new theories of how nervous systems operate, as well as a diversity of tools for the neuroscience and computational communities.

This project is funded by Integrative Strategies for Understanding Neural and Cognitive Systems (NSF-NCS), a multidisciplinary program jointly supported by the Directorates for Computer and Information Science and Engineering (CISE), Education and Human Resources (EHR), Engineering (ENG), and Social, Behavioral, and Economic Sciences (SBE).