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Cosmological tests with strong gravitational lenses using gaussian processes

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arXiv 2018年

作者： Yennapureddy, Manoj K. Melia, Fulvio Department of Physics University of Arizona AZ85721 United States Department of Physics Applied Math Program Department of Astronomy University of Arizona TucsonAZ85721 United States

Strong gravitational lenses provide source/lens distance ratios Dobsuseful in cosmological tests. Previously, a catalog of 69 such systems was used in a one-on-one comparison between the standard model, λCDM, and the Rh = ct universe, which has thus far been favored by the application of model selection tools to many other kinds of data. But in that work, the use of model parametric fits to the observations could not easily distinguish between these two cosmologies, in part due to the limited measurement precision. Here, we instead use recently developed methods based on Gaussian Processes (GP), in which Dobs may be reconstructed directly from the data without assuming any parametric form. This approach not only smooths out the reconstructed function representing the data, but also reduces the size of the 1s confidence regions, thereby providing greater power to discern between different models. With the current sample size, we show that analyzing strong lenses with a GP approach can definitely improve the model comparisons, producing probability differences in the range ∼ 10 - 30%. These results are still marginal, however, given the relatively small sample. Nonetheless, we conclude that the probability of Rh = ct being the correct cosmology is somewhat higher than that of λCDM, with a degree of significance that grows with the number of sources in the subsamples we consider. Future surveys will significantly grow the catalog of strong lenses and will therefore benefit considerably from the GP method we describe here. In addition, we point out that if the Rh= ctuniverse is eventually shown to be the correct cosmology, the lack of free parameters in the study of strong lenses should provide a remarkably powerful tool for uncovering the mass structure in lensing galaxies. Copyright © 2018, The Authors. All rights reserved.

关键词： Cosmology

Luminescence study and Judd-Ofelt analysis of CaO-BaO-P₂O₅ glasses doped with Nd³⁺ ions

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Luminescence study and Judd-Ofelt analysis of CaO-BaO-P<sub>...

International Conference on Science and Technology of Emerging Materials (STEAMa)

作者： Chanthima, N. Kaewkhao, J. Tariwong, Y. Sangwaranatee, N. Sangwaranatee, N. W. Nakhon Pathom Rajabhat Univ Fac Sci & Technol Phys Program Muang 73000 Nakhon Pathom Thailand Nakhon Pathom Rajabhat Univ Ctr Excellence Glass Technol & Mat Sci CEGM Muang 73000 Nakhon Pathom Thailand Suan Sunandha Rajabhat Univ Fac Sci & Technol Applied Phys Bangkok 10300 Thailand Suan Sunandha Rajabhat Univ Fac Sci & Technol Informat Math Bangkok 10300 Thailand

Neodymium (Nd3+) doped calcium barium phosphate glasses have been studied in different concentration of Nd3+ ions. The absorption and luminescence spectra, the Judd-Ofelt (JO) intensity parameters Omega 2,4,6 and other radiative properties, which is radiative transition probabilities (AR), stimulated emission cross-sections (sigma(lambda(p)) and branching ratios (beta(R)) were calculated. These glass samples have shown strong absorption bands in the visible (VIS) and near-infrared (NIR) region. The emission spectra of glass samples have exhibited three emission transitions, which are assigned to F-4(3/2)-> I-4(9/2), (F3/2 -> I11/2)-F-4-I-4 and (F3/2 -> I13/2)-F-4-I-4 transitions, respectively. Also, the results obtained were compared with reports on similar glasses. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Judd-Ofelt analysis Luminescence Neodymium Phosphate glasses

A stochastic MPEC approach for grid tariff design with demand-side flexibility

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ENERGY SYSTEMS-OPTIMIZATION MODELING SIMULATION AND ECONOMIC ASPECTS 2023年第3期14卷 707-729页

作者： Askeland, Magnus Burandt, Thorsten Gabriel, Steven A. Energy Systems SINTEF Energy Research Trondheim Norway Department of Electric Power Engineering Norwegian University of Science and Technology Trondheim Norway Workgroup for Infrastructure Policy Technical University of Berlin Berlin Germany The Energy Transportation Environment Department German Institute for Economic Research (DIW Berlin) Berlin Germany Department of Industrial Economics and Technology Management Norwegian University of Science and Technology Trondheim Norway Department of Mechanical Engineering Applied Math and Statistics Scientific Computation Program University of Maryland College Park MD USA

As the end-users increasingly can provide flexibility to the power system, it is important to consider how this flexibility can be activated as a resource for the grid. Electricity network tariffs is one option that can be used to activate this flexibility. Therefore, by designing efficient grid tariffs, it might be possible to reduce the total costs in the power system by incentivizing a change in consumption patterns. This paper provides a methodology for optimal grid tariff design under decentralized decision-making and uncertainty in demand, power prices, and renewable generation. A bilevel model is formulated to adequately describe the interaction between the end-users and a distribution system operator. In addition, a centralized decision-making model is provided for benchmarking purposes. The bilevel model is reformulated as a mixed-integer linear problem solvable by branch-and-cut techniques. Results based on both deterministic and stochastic settings are presented and discussed. The findings suggest how electricity grid tariffs should be designed to provide an efficient price signal for reducing aggregate network peaks.

关键词： Bilevel problem Grid tariffs mathematical program with equilibrium constraints (MPEC) Uncertainty

Model selection with strong-lensing systems

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arXiv 2018年

作者： Leaf, Kyle Melia, Fulvio Department of Physics University of Arizona ArizonaAZ85721 United States Department of Physics Applied Math Program Department of Astronomy University of Arizona ArizonaAZ85721 United States

In this paper, we use an unprecedentedly large sample (158) of confirmed strong lens systems for model selection, comparing five well studied Friedmann-Robertson- Walker cosmologies: ACDM, wCDM (the standard model with a variable darkenergy equation of state), the Rh= ct universe, the (empty)Milne cosmology, and the classical Einstein-de Sitter (matter dominated) *** first use these sources to optimize the parameters in the standard model and show that they are consistent with Planck, though the quality of the best fit is not *** demonstrate that this is likely due to under-reported errors, or to errors yet to be included in this kind of analysis. We suggest that the missing dispersion may be due to scatter about a pure single isothermal sphere (SIS) model that is often assumed for the mass distribution in these lenses. We then use the Bayes information criterion, with the inclusion of a suggested SIS dispersion, to calculate the relative likelihoods and ranking of these models, showing that Milne and Einstein-de Sitter are completely ruled out, while Rh= ct is preferred over ACDM/wCDM with a relative probability of ∼ 73% versus ∼ 24%. The recently reported sample of new strong lens candidates by the Dark Energy Survey, if confirmed, may be able to demonstrate which of these two models is favoured over the other at a level exceeding 3s. Copyright © 2018, The Authors. All rights reserved.

关键词： Equations of state

Reconstruction of the HII Galaxy Hubble Diagram using Gaussian Processes

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arXiv 2017年

作者： Yennapureddy, Manoj K. Melia, Fulvio Department of Physics University of Arizona TucsonAZ85721 United States The Applied Math Program and Steward Observatory Department of Physics University of Arizona TucsonAZ85721 United States

The Hubble diagram constructed using HII galaxies (HIIGx) and Giant extragalactic HII regions (GEHR) as standard candles already extends beyond the current reach of Type Ia SNe. A sample of 156 HIIGx and GEHR sources has been used previously to compare the predictions of CDM and Rh = ct, the results of which suggested that the HIIGx and GEHR sources strongly favour the latter over the former. But this analysis was based on the application of parametric fits to the data and the use of information criteria, which disfavour the less parsimonious models. In this paper, we advance the use of HII sources as standard candles by utilizing Gaussian processes (GP) to reconstruct the distance modulus representing these data without the need to pre-assume any particular model, none of which may in the end actually be the correct cosmology. In addition, this approach tightly constrains the 1confidence region of the reconstructed function, thus providing a better tool with which to differentiate between competing cosmologies. With this approach, we show that the Planck concordance model is in tension with the HII data at more than 2.5, while Rh = ct agrees with the GP reconstruction very well, particularly at redshifts & 10-3. Copyright © 2017, The Authors. All rights reserved.

关键词： Galaxies

On Complex Analytic tools, and the Holomorphic Rotation methods

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arXiv 2022年

作者： Coifman, Ronald R. Peyrière, Jacques Weiss, Guido Department of Mathematics Program in Applied Mathematics Yale University New HavenCT06510 United States Institut de Mathématiques d'Orsay CNRS Université Paris-Saclay Orsay91405 France

We describe recent nonlinear analytic approximation tools in the classical setting of Hardy spaces in the upper half plane and show how to transfer them to the higher dimensional real setting of harmonic functions in upper half spaces. It is known [6] that all harmonic functions in higher dimensions are combinations of holomorphic functions on 2 dimensional planes, extended as, constant in normal directions. We derive representation theorems, with corresponding isometries, opening the door for applications in higher dimensions, to the processing of highly oscillatory multidimensional signals. © 2022, CC BY.

关键词： Harmonic functions

Multiscale decompositions of Hardy spaces

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arXiv 2021年

作者： Coifman, Ronald R. Peyrière, Jacques Department of Mathematics Program in Applied Mathematics Yale University New HavenCT06510 United States Institut de Mathématiques d’Orsay CNRS Université Paris-Saclay Orsay91405 France

Preconditioners for regularized image superresolution

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Preconditioners for regularized image superresolution

International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： N. Nguyan G. Golub P. Milanfar Sci. Comput. & Comput. Math. Program Stanford Univ. CA USA Scientific Computing and Computational Mathematics Program University of Stanford Stanford CA USA Applied Electromagnetics Lab SRI International Inc. Menlo Park CA USA

Superresolution reconstruction produces a high resolution image from a set of low resolution images. Previous work on superresolution had not adequately addressed the computational issues for this problem. In this paper, we propose efficient block circulant preconditioners for solving the regularized superresolution problem by conjugate gradients. The effectiveness of the preconditioners is demonstrated with superresolution results for a simulated image sequence and a FLIR image sequence.

关键词： Image resolution Layout Spatial resolution Pixel Image reconstruction Image sequences Motion estimation Solids Equations Scientific computing

Model selection using cosmic chronometers with gaussian processes

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arXiv 2018年

作者： Melia, Fulvio Yennapureddy, Manoj K. Department of Physics Applied Math Program and Steward Observatory University of Arizona TucsonAZ85721 United States Department of Physics University of Arizona TucsonAZ85721 United States John Woodruff Simpson Fellow

The use of Gaussian Processes with a measurement of the cosmic expansion rate based solely on the observation of cosmic chronometers provides a completely cosmology-independent reconstruction of the Hubble constant H(z) suitable for testing different models. The corresponding dispersion σH is smaller than ∼ 9% over the entire redshift range (0 . z . 2) of the observations, rivaling many kinds of cosmological measurements available today. We use the reconstructed H(z) function to test six different cosmologies, and show that it favours the Rh = ct universe, which has only one free parameter (i.e., H0) over other models, including Planck ΛCDM. The parameters of the standard model may be re-optimized to improve the fits to the reconstructed H(z) function, but the results have smaller p-values than one finds with Rh = ct. Copyright © 2018, The Authors. All rights reserved.

关键词： Chronometers