Physical Sciences and Mathematics Commons^™

Constraining H0 Via Extragalactic Parallax, Nicholas Ferree

Honors Theses

We examine the prospects for measurement of the Hubble parameter 𝐻₀ via observation of the secular parallax of other galaxies due to our own motion relative to the cosmic microwave background rest frame. Peculiar velocities make distance measurements to individual galaxies highly uncertain, but a survey sampling many galaxies can still yield a precise 𝐻₀ measurement. We use both a Fisher information formalism and simulations to forecast errors in 𝐻₀ from such surveys, marginalizing over the unknown peculiar velocities. The optimum survey observes ∼ 102 galaxies within a redshift 𝐻₀max = 0.06. The required errors …

Study Of Missing Mass Background In The Clas12 Detector, Jessie Hess, Gerard P. Gilfoyle, Lamya Baashen

Honors Theses

At Jefferson Lab we use the CLAS12 detector to measure the neutron magnetic form factor. An accurate measurement of the CLAS12 neutron detection efficiency (NDE) is required. We use the nuclear reaction ���� → ��′��+�� as a source of tagged neutrons and obtain the NDE from the ratio of expected neutrons to detected ones. We assume the final state consists of ��′��+�� only, use the ��′��+ information to predict the neutron's position(expected) and then search for that neutron(detected). We select neutrons with the missing mass (MM) technique. We use simulation to validate our methods. We simulated events with the Monte-Carlo …

Estimation Of Pure B Power In Polarized Cmb Data Via Gibbs Sampling., Joseph Sterling

Honors Theses

In the search for effective processes to estimate E and B spectra from polarized data, Gibbs Sampling has proven to be a powerful method. In the search for B modes, it is essential to avoid a false positive detection due to contamination from the larger E component. It is therefore of interest to combine Gibbs sampling with methods to “purify” the B modes, ensuring that a B-mode detection is robust. This goal can be achieved by compelling the Gibbs Sampler to estimate a pure B spectrum. The method we chose to implement involves an artificially inflated E spectrum, which “forces” …

Cosmological Inflation In N-Dimensional Gaussian Random Fields With Algorithmic Data Compression, Connor A. Painter

Honors Theses

The leading modern theories of cosmological inflation are increasingly multi-dimensional. The “inflaton field” φ that has been postulated to drive accelerating expansion in the very early universe has a corresponding potential function V , the details of which, such as the number of dimensions and shape, have yet to be specified. We consider a natural hypothesis that V ought to be maximally random. We realize this idea by defining the V as a Gaussian random field in some number N of dimensions. We repeatedly simulate of the evolution of φ given a set of conditions on the “landscape” of V …

Using 3-Dimensional Ffts To Simulate Cmb Maps On A Spherical Cap, Eric Goetz

Honors Theses

The current methods of simulating the Cosmic Microwave Background (CMB) involve either simulating the entire sky using spherical transforms or simulating a at patch with fast Fourier transforms (FFTs). For patches that are too large to be considered at but much less than the full sky, the former method is inecient and the latter is inaccurate. One alternative method of CMB simulation is to simulate the random processes behind the CMB in a 3-dimensional box that contains the part of the sphere that we want to measure. Then, we can select the points we want from the box. This method …

Polychromatic Map-Making With Asymmetric Antenna Patterns, Connor Mooney

Honors Theses

Imaging telescopes with asymmetric antenna patterns that vary with wavelength can create time-ordered data that may be processed into multiple images corresponding to different bands of wavelengths from just a single set of scans. The imaging telescope named QUBIC has this property and is the inspiration behind this project. Our goal is to quantify, both statistically and analytically, the ability of these telescopes to perform such a reconstruction given different cases. In the case that the telescope is observing the full sky, we reconstruct our maps via a spherical harmonic basis. In this way, the reconstructed images are described as …

Waveband Luminosity Correlations In Flux-Limited Multiwavelength Data And The Schwinger Effect In Minkowski & De Sitter Space-Times, Syed Jibran Haider

Honors Theses

The first part of the thesis explores key findings determined from plotting multiple waveband luminosity and redshift correlations in quasar data binned in redshift. The second part of the thesis concerns itself with applying Picard-Lefschetz theory to pair particle production in de Sitter space-time (with or without a constant electric field).

Analysis Of A Custom Support Vector Machine For Photometric Redshift Estimation And The Inclusion Of Galaxy Shape Information, Evan Jones, J. Singal

Honors Theses

Aims. We present a custom support vector machine classification package for photometric redshift estimation, including comparisons with other methods. We also explore the efficacy of including galaxy shape information in redshift estimation. Support vector machines, a type of machine learning, utilize optimization theory and supervised learning algorithms to construct predictive models based on the information content of data in a way that can treat different input features symmetrically, which can be a useful estimator of the information contained in additional features beyond photometry, such as those describing the morphology of galaxies.

Methods. The custom support vector machine package we have …

Study Of The Neutron Detection Efficiency Of The Clas12 Detector, Keegan Sherman

Honors Theses

One of the central physics goals of Jefferson Lab is to understand how quarks and gluons form nuclei. The 12 GeV upgrade is nearing completion and a new detector, CLAS12, is being built in Hall B. One of the approved experiments will measure the magnetic form factor of the neutron (Gn ). To make this measurement, the ratio of electron-neutron (e-n) to electron-proton (e-p) scattering events will be extracted from deuterium in quasi-elastic kinematics. A major source of systematic uncertainty is the neutron detection efficiency (NDE) of CLAS12. To better understand the NDE I used the Monte Carlo …

An Examination Of The Cmb Large-Angle Suppression, Ellis Herman

Honors Theses

As shown by COBE­DMR and then by the Wilkinson Anisotropy Probe (WMAP), there exists an anomaly in the correlation function of the cosmic microwave background (CMB) radiation, namely that said correlation function is suppressed to zero on large angular scales. This observation conflicts with the prediction made by Lambda­CDM, the standard model of cosmology, indicating either necessary changes to the standard model or that our universe is a rare fluke within LCDM ­ such suppressions are seen in only about 0.3% of universes predicted by LCDM. To differentiate into which of these categories our universe falls, we have attempted to …