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Three and Four Dimensional Geometric Analyses of Causal Regions During Inflation
This thesis expands upon the work done in Hogan & Meyer (2022) concerning the theory that the symmetries underlying quantum entanglement of inflationary horizons may explain certain suggestive regions of the correlation function of the Cosmic Microwave Background (CMB) temperature anisotropies. We seek to create higher dimensional, interactive versions of figures explaining this theory as a pedagogical tool for the understanding of this complicated subject. Using an accompanying python notebook to this paper, we explain some important predictions of this theory using our higher dimensional figures. In particular, we replicate the geometric arrangement of intersecting spherical horizons from Hogan & Meyer (2022) as well as adding the null geodesics of photons traversing them. We explore this system in three and four dimensions in order to demonstrate results such as that in the region C() = 0. In the appendix, we derive the null geodesics in an exponentially inflating spacetime used in the creation of these figures. These predicted values of the CMB correlation function using this theory seem to agree more strongly with the real world data than standard inflation theories; as such this thesis hopes to make this theory more accessible for further study
The Pantheon+ Analysis: Cosmological Constraints
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves of 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift from to 2.26. This work features an increased sample size, increased redshift span, and improved treatment of systematic uncertainties in comparison to the original Pantheon analysis and results in a factor of two improvement in cosmological constraining power. For a FlatCDM model, we find from SNe Ia alone. For a FlatCDM model, we measure from SNe Ia alone, H km s Mpc when including the Cepheid host distances and covariance (SH0ES), and when combining the SN likelihood with constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); both values are consistent with a cosmological constant. We also present the most precise measurements to date on the evolution of dark energy in a FlatCDM universe, and measure from Pantheon+ alone, H km s Mpc when including SH0ES, and when combining Pantheon+ with CMB and BAO data. Finally, we find that systematic uncertainties in the use of SNe Ia along the distance ladder comprise less than one third of the total uncertainty in the measurement of H and cannot explain the present "Hubble tension" between local measurements and early-Universe predictions from the cosmological model
The Pantheon+ analysis : cosmological constraints
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves of 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift from z = 0.001 to 2.26. This work features an increased sample size from the addition of multiple cross-calibrated photometric systems of SNe covering an increased redshift span, and improved treatments of systematic uncertainties in comparison to the original Pantheon analysis, which together result in a factor of 2 improvement in cosmological constraining power. For a flat ÎCDM model, we find ΩM = 0.334 ± 0.018 from SNe Ia alone. For a flat w0CDM model, we measure w0 = â0.90 ± 0.14 from SNe Ia alone, H0 = 73.5 ± 1.1 km sâ1 Mpcâ1 when including the Cepheid host distances and covariance (SH0ES), and w0 = -0.978-+0.0310.024 when combining the SN likelihood with Planck constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); both w0 values are consistent with a cosmological constant. We also present the most precise measurements to date on the evolution of dark energy in a flat w0waCDM universe, and measure wa = -0.1-+2.00.9 from Pantheon+ SNe Ia alone, H0 = 73.3 ± 1.1 km sâ1 Mpcâ1 when including SH0ES Cepheid distances, and wa = -0.65-+0.320.28 when combining Pantheon+ SNe Ia with CMB and BAO data. Finally, we find that systematic uncertainties in the use of SNe Ia along the distance ladder comprise less than one-third of the total uncertainty in the measurement of H0 and cannot explain the present âHubble tensionâ between local measurements and early universe predictions from the cosmological model
The Dark Energy Survey Supernova Program results: type Ia Supernova brightness correlates with host galaxy dust
Cosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between colour and luminosity (ÎČ) and do not account for varying host-galaxy dust properties. However, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. Here, we take advantage of state-of-the-art modelling of galaxy properties to characterize dust parameters (dust attenuation AV, and a parameter describing the dust law slope RV) for 1100 Dark Energy Survey (DES) SN host galaxies. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN cosmology: (1) there exists a large range (âŒ1â6) of host RV; (2) high-stellar mass hosts have RV on average âŒ0.7 lower than that of low-mass hosts; (3) for a subsample of 81 spectroscopically classified SNe there is a significant (>3Ï) correlation between the Hubble diagram residuals of red SNe Ia and the host RV that when corrected for reduces scatter by âŒ13 per centâŒ13 per cent and the significance of the âmass stepâ to âŒ1Ï. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling âmass stepâ and intrinsic scatter (Ïint) in SN Ia analyses