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We investigate the impact and mitigation of extragalactic foregrounds for the cosmic microwave background (CMB) lensing power spectrum analysis of Atacama Cosmology Telescope (ACT) data release 6 (DR6) data. Two independent microwave sky simulations are used to test a range of mitigation strategies. We demonstrate that finding and then subtracting point sources, finding and then subtracting models of clusters, and using a profile bias-hardened lensing estimator together reduce the fractional biases to well below statistical uncertainties, with the inferred lensing amplitude, A lens, biased by less than 0.2σ. We also show that another method where a model for the cosmic infrared background (CIB) contribution is deprojected and high-frequency data from Planck is included has similar performance. Other frequency-cleaned options do not perform as well, either incurring a large noise cost or resulting in biased recovery of the lensing spectrum. In addition to these simulation-based tests, we also present null tests on the ACT DR6 data for sensitivity of our lensing spectrum estimation to differences in foreground levels between the two ACT frequencies used, while nulling the CMB lensing signal. These tests pass whether the nulling is performed at the map or bandpower level. The CIB-deprojected measurement performed on the DR6 data is consistent with our baseline measurement, implying that contamination from the CIB is unlikely to significantly bias the DR6 lensing spectrum. This collection of tests gives confidence that the ACT DR6 lensing measurements and cosmological constraints presented in companion papers to this work are robust to extragalactic foregrounds.

Over the past two decades, measurements of the Cosmic Microwave Background (CMB) have provided a wealth of information about our Universe. The current and future wide-field CMB surveys, such as ACT, SO, CMB-S4, and CMB-HD, will continue this advancement by measuring the microwave sky with unprecedented sensitivity. In order to extract the maximum amount of information from these new measurements, we will need to improve our analyses, generate realistic simulations, and control for potential systemic effects. The work described in this thesis advances several new methods for making the CMB a better window into the inner workings of the cosmos.In the first part of this work, we undo the lensing distortion effect from the CMB power spectra using internally reconstructed lensing maps. For the first time, we demonstrate a parameter analysis using \"delensed\" CMB power spectra. This new approach is expected to be more sensitive to the condition of the primordial Universe by removing the lensing distortion that obscures images of the primordial perturbations.In the second part of this work, we present a method to mass-produce non-Gaussian extragalactic foreground simulations. Using Deep Learning techniques, we generate a set of 500 high-resolution, full-sky millimeter-wave simulations that include both lensed CMB maps and correlated foreground components. These simulations provide a way to statistically quantify the effect of the foregrounds throughout the CMB analysis.In the last part of this work, we present a foreground mitigation strategy for an ultra high-resolution (L ∈ [5000,20000]) CMB lensing measurement from CMB-HD survey. We find that our strategy can sufficiently remove the effects of the foreground below the detection limit and enable robust detection of CMB lensing potential on extremely small scales.

In this study, the performance of an air source heat pump system installed in a commercial building is analyzed using the developed heat pump performance model and building load simulation data of several regions in Korea. The performance test of an air source heat pump system with a variable speed compressor is tested to develop model that considers changes in the performance characteristics of the heat pump system under various operating conditions. The heat pump system is installed in an environmental chamber, and the experimental equipment is set up according to the manufacturer’s specifications as well as the AHRI 1230 test specifications. The performance test conditions of the heat pump system are selected using a central composite design method, in which 29 points for each cooling and heating mode are selected. The developed performance model based on experimental data predicts experimental values with an error of ±5 %. Building cooling and heating loads in three regions in Korea are analyzed using TRNSYS software, which includes standard building and weather data from Seoul, Daejeon and Busan in Korea. The effects of outdoor air temperature and part load ratio on the performance and regional monthly average power consumption of the heat pump system are analyzed.

A promising way to measure the distribution of matter on small scales (k ~ 10 hMpc^-1) is to use gravitational lensing of the Cosmic Microwave Background (CMB). CMB-HD, a proposed high-resolution, low-noise millimeter survey over half the sky, can measure the CMB lensing auto spectrum on such small scales enabling measurements that can distinguish between a cold dark matter (CDM) model and alternative models designed to solve problems with CDM on small scales. However, extragalactic foregrounds can bias the CMB lensing auto spectrum if left untreated. We present a foreground mitigation strategy that provides a path to reduce the bias from two of the most dominant foregrounds, the thermal Sunyaev-Zel'dovich effect (tSZ) and the Cosmic Infrared Background (CIB). Given the level of realism included in our analysis, we find that the tSZ alone and the CIB alone bias the lensing auto spectrum by 0.6 sigma and 1.1 sigma respectively, in the lensing multipole range of L in [5000,20000] for a CMB-HD survey; combined these foregrounds yield a bias of only 1.3 sigma. Including these foregrounds, we also find that a CMB-HD survey can distinguish between a CDM model and a 10^-22 eV FDM model at the 5 sigma level. These results provide an important step in demonstrating that foreground contamination can be sufficiently reduced to enable a robust measurement of the small-scale matter power spectrum with CMB-HD.

We present 500 high-resolution, full-sky millimeter-wave Deep Learning (DL) simulations that include lensed CMB maps and correlated foreground components. We find that these MillimeterDL simulations can reproduce a wide range of non-Gaussian summary statistics matching the input training simulations, while only being optimized to match the power spectra. The procedure we develop in this work enables the capability to mass produce independent full-sky realizations from a single expensive full-sky simulation, when ordinarily the latter would not provide enough training data. We also circumvent a common limitation of high-resolution DL simulations that they be confined to small sky areas, often due to memory or GPU issues; we do this by developing a \"stitching\" procedure that can faithfully recover the high-order statistics of a full-sky map without discontinuities or repeated features. In addition, since our network takes as input a full-sky lensing convergence map, it can in principle take a full-sky lensing convergence map from any large-scale structure (LSS) simulation and generate the corresponding lensed CMB and correlated foreground components at millimeter wavelengths; this is especially useful in the current era of combining results from both CMB and LSS surveys, which require a common set of simulations.

We present a new method which leverages conditional Generative Adversarial Networks (cGAN) to reconstruct galaxy cluster convergence from lensed CMB temperature maps. Our model is constructed to emphasize structure and high-frequency correctness relative to the Residual U-Net approach presented by Caldeira, et. al. (2019). Ultimately, we demonstrate that while both models perform similarly in the no-noise regime (as well as after random off-centering of the cluster center), cGAN outperforms ResUNet when processing CMB maps noised with 5uK/arcmin white noise or astrophysical foregrounds (tSZ and kSZ); this out-performance is especially pronounced at high l, which is exactly the regime in which the ResUNet under-performs traditional methods.

We present cosmological constraints from a gravitational lensing mass map covering 9400 sq. deg. reconstructed from CMB measurements made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with BAO measurements (from SDSS and 6dF), we obtain the amplitude of matter fluctuations \\(_8 = 0.819 0.015\\) at 1.8% precision, \\(S_8_8(_ m/0.3)^0.5=0.8400.028\\) and the Hubble constant \\(H_0= (68.3 1.1)\\, km\\,s^-1\\,Mpc^-1\\) at 1.6% precision. A joint constraint with CMB lensing measured by the Planck satellite yields even more precise values: \\(_8 = 0.812 0.013\\), \\(S_8_8(_ m/0.3)^0.5=0.8310.023\\) and \\(H_0= (68.1 1.0)\\, km\\,s^-1\\,Mpc^-1\\). These measurements agree well with \\(\\)CDM-model extrapolations from the CMB anisotropies measured by Planck. To compare these constraints to those from the KiDS, DES, and HSC galaxy surveys, we revisit those data sets with a uniform set of assumptions, and find \\(S_8\\) from all three surveys are lower than that from ACT+Planck lensing by varying levels ranging from 1.7-2.1\\(\\). These results motivate further measurements and comparison, not just between the CMB anisotropies and galaxy lensing, but also between CMB lensing probing \\(z 0.5-5\\) on mostly-linear scales and galaxy lensing at \\(z 0.5\\) on smaller scales. We combine our CMB lensing measurements with CMB anisotropies to constrain extensions of \\(\\)CDM, limiting the sum of the neutrino masses to \\( m_ < 0.13\\) eV (95% c.l.), for example. Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the \\(\\)CDM model, while paving a promising path for neutrino physics with gravitational lensing from upcoming ground-based CMB surveys.

The thermal and kinematic Sunyaev-Zel'dovich effects (tSZ, kSZ) probe the thermodynamic properties of the circumgalactic and intracluster medium (CGM and ICM) of galaxies, groups, and clusters, since they are proportional, respectively, to the integrated electron pressure and momentum along the line-of-sight. We present constraints on the gas thermodynamics of CMASS galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) using new measurements of the kSZ and tSZ signals obtained in a companion paper. Combining kSZ and tSZ measurements, we measure within our model the amplitude of energy injection \\( M_ c^2\\), where \\(M_\\) is the stellar mass, to be \\(=(409)10^-6\\), and the amplitude of the non-thermal pressure profile to be \\(_ Nth<0.2\\) (2\\(\\)), indicating that less than 20% of the total pressure within the virial radius is due to a non-thermal component. We estimate the effects of including baryons in the modeling of weak-lensing galaxy cross-correlation measurements using the best-fit density profile from the kSZ measurement. Our estimate reduces the difference between the original theoretical model and the weak-lensing galaxy cross-correlation measurements in arXiv:1611.08606 by half but does not fully reconcile it. Comparing the tSZ measurements to cosmological simulations, we find that simulations underestimate the CGM pressure at large radii while they fare better in comparison with the kSZ measurements. This suggests that the energy injected via feedback models in the simulations that we compared against does not sufficiently heat the gas at these radii. We do not find significant disagreement at smaller radii. These measurements provide novel tests of current and future simulations. This work demonstrates the power of joint, high signal-to-noise kSZ and tSZ observations, upon which future cross-correlation studies will improve.

These notes are very much work-in-progress and simply intended to showcase, in various degrees of details (and rigour), some of the cosmology calculations that class_sz can do. We describe the class_sz code in C, Python and Jax. Based on the Boltzmann code class, it can compute a wide range of observables relevant to current and forthcoming CMB and Large Scale Structure surveys. This includes galaxy shear and clustering, CMB lensing, thermal and kinetic Sunyaev and Zeldovich observables, Cosmic Infrared Background, cross-correlations and three-point statistics. Calculations can be done either within the halo model or the linear bias model. For standard \\(\\)CDM cosmology and extensions, class_sz uses high-accuracy cosmopower emulators of the CMB and matter power spectrum to accelerate calculations. With this, along with efficient numerical integration routines, most class_sz output can be obtained in less than 500 ms (CMB \\(C_\\)'s or matter \\(P(k)\\) take \\(O(1ms)\\)), allowing for fast or ultra-fast parameter inference analyses. Parts of the calculations are \"jaxified\", so the software can be integrated into differentiable pipelines.

Galaxy clusters are an important tool for cosmology, and their detection and characterization are key goals for current and future surveys. Using data from the Wide-field Infrared Survey Explorer (WISE), the Massive and Distant Clusters of WISE Survey (MaDCoWS) located 2,839 significant galaxy overdensities at redshifts \\(0.7 z 1.5\\), which included extensive follow-up imaging from the Spitzer Space Telescope to determine cluster richnesses. Concurrently, the Atacama Cosmology Telescope (ACT) has produced large area mm-wave maps in three frequency bands along with a large catalog of Sunyaev-Zeldovich (SZ) selected clusters, as part of its Data Release 5 (DR5). Using the maps and cluster catalog from DR5, we explore the scaling between SZ mass and cluster richness. We use complementary radio survey data from the Very Large Array, submillimeter data from Herschel, and ACT 224~GHz data to assess the impact of contaminating sources on the SZ signals. We then use a hierarchical Bayesian model to fit the mass-richness scaling relation. We find that MaDCoWS clusters have submillimeter contamination which is consistent with a gray-body spectrum, while the ACT clusters are consistent with no submillimeter emission on average. We find the best fit ACT SZ mass vs. MaDCoWS richness scaling relation has a slope of \\( = 1.84^+0.15_-0.14\\), where the slope is defined as \\(M _15^\\) where \\(_15\\) is the richness. Additionally, we find that the approximate level of in-fill of the ACT and MaDCoWS cluster SZ signals to be at the percent level