Bulletin of the American Physical Society
2016 Annual Meeting of the APS Mid-Atlantic Section
Volume 61, Number 16
Saturday–Sunday, October 15–16, 2016; Newark, Delaware
Session H1: Astronomy, Astrophysics and High Energy Physics III |
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Chair: John Gizis, University of Delaware Room: Sharp Laboratory 123 |
Sunday, October 16, 2016 3:30PM - 4:06PM |
H1.00001: The Large Scale Polarization of the Cosmic Microwave Background Invited Speaker: David Chuss Cosmology has undergone a revolution in the past two decades. Detailed observations of the cosmic microwave background (CMB) have played a crucial role in solidifying the $\Lambda$CDM model of the universe. The universe has cooled and expanded over its 13.8 billion year history. It is dominated by dark energy, and the evolution of structure is driven by gravitational action on an initially small inhomogeneity of dark matter. Current data provide strong hints that the universe underwent an exponential expansion in its first fraction of a second. This epoch of inflation provides an explanation for the measured geometric flatness of the universe, a solution to the horizon problem, and a source of the initial inhomogeneity. Inflation predicts a stochastic background of gravitational waves that would polarize the cosmic microwave background in a specific pattern. Measurement of this signal would provide tangible evidence for inflation along with an opportunity to study physics at energies a trillion times higher than those accessible by the Large Hadron Collider. The Cosmology Large Angular Scale Surveyor (CLASS) is an array of microwave telescopes located in the Atacama Desert in Chile that is designed to search for this signal. [Preview Abstract] |
Sunday, October 16, 2016 4:06PM - 4:18PM |
H1.00002: Search for high energy neutrinos from Seyfert galaxies using IceCube Ben Relethford Since its construction began in 2005, The IceCube Neutrino Observatory, a cubic kilometer Cherenkov detector buried deep in the geographic South Pole ice, has searched for a high-energy astrophysical neutrino flux. In 2013, IceCube observed such a flux deviating at least 5.7$\sigma$ above atmospheric backgrounds. However, analyses of promising source candidates such as blazars (a type of radio-loud Active Galactic Nucleus, or AGN) and gamma ray bursts have found no evidence of neutrino emission, placing stringent constraints on their possible contribution to the observed extraterrestrial neutrino flux. This analysis considers a numerous yet comparatively low-intensity type of radio-quiet AGN known as Seyfert galaxies as a new candidate source of high energy astrophysical neutrinos. We obtain a catalog of Seyfert galaxies from the 70 month catalog of high-energy x-ray sources as identified by the BAT detector on the \textit{Swift} satellite. We simultaneously study these Seyfert galaxies via a stacking analysis, which is particularly well-suited to a source class with high abundance but relatively low-intensity. This analysis will probe for the first time whether Seyfert galaxies contribute significantly to the observed, but so far unresolved astrophysical neutrino flux. [Preview Abstract] |
Sunday, October 16, 2016 4:18PM - 4:30PM |
H1.00003: A detailed study of the Cas A and IC 443 supernova remnants in $\gamma $-rays with VERITAS. Sajan Kumar The origin of cosmic rays has been unresolved ever since their discovery over one hundred years ago. The shock front created when the blast wave from a supernova explosion moves through the interstellar medium has been widely accepted as one possible acceleration site for cosmic rays. This connection between supernova remnant (SNR) shocks and cosmic rays is substantiated by the detection of high energy (HE; 100 MeV to 100 GeV) and very high energy (VHE; 100 GeV to 100 TeV) gamma rays from young and middle-aged SNRs. Gamma-rays can be produced both by electrons, through non-thermal Bremsstrahlung and inverse Compton scattering, and by protons, through proton-proton collisions and subsequent neutral pion decay. Therefore, the interpretation of the gamma-ray observations is not unique. To disentangle and quantify the contributions of electrons and protons to the gamma-ray flux, it is necessary to measure precisely the spectra and morphology of SNRs over a broad range of gamma-ray energies. Two well-known SNRs, Cassiopeia A (a young and bright SNR) and IC 443 (a middle-aged SNR interacting with molecular cloud), are well studied in the gamma-ray regime. Here, we will present the detailed spectral and morphological results from these two SNRs using observations by the VERITAS telescope array. [Preview Abstract] |
Sunday, October 16, 2016 4:30PM - 4:42PM |
H1.00004: Development and Validation of Satellite Image Registration Techniques Azubuike Okorie, Sokratis Makrogiannis In this work we studied and developed feature- and intensity-based registration techniques for satellite images. Image registration is the process of aligning two images of the same scene that may include viewpoint, temporal, or sensor variations. Registration of satellite images is very significant as results can be used for earth observation, change detection, urban planning, study of climate changes, meteorology and other applications. Our focus is on the application of image features and intensities for registration. We applied state-of-the-art feature detection, extraction and matching techniques to estimate the geometric transformation that would align two images of the same scene. We also used intensity-based methods to register pairs of misaligned images of the same scene. We used Ground Truth data to validate the results of registration from both methods by computing the pixel error. Qualitative and quantitative comparisons suggest that the utilization of features may improve registration accuracy compared to intensity-based approaches especially for multi-sensor registration. Preliminary results indicate that automated image registration may be used for remote sensing applications. [Preview Abstract] |
Sunday, October 16, 2016 4:42PM - 4:54PM |
H1.00005: Analysis of North Sky Cosmic Ray Anisotropy with Atmospheric Neutrinos Elizabeth Wills Since the discovery of Cosmic Ray anisotropy, no experiment has definitively discovered the source of this unexpected phenomenon. Studying the cosmic rays' neutral daughter particles with pointing capabilities, like neutrinos, could shed new light. This can be done at two levels; a source which produces cosmic rays must also produce high energy astrophysical neutrinos, and low energy atmospheric neutrinos are made when the cosmic rays interact with the atmosphere. This analysis focuses on atmospheric neutrinos detected by IceCube, a Cherenkov detector instrumenting a kilometer cubed of glacial ice at the South Pole. The anisotropy and its energy dependence have been studied in the Southern sky using atmospheric muons by IceCube. In the North, gamma ray detectors, such as HAWC, and Argo-YBJ, have observed this anisotropy in cosmic ray showers. Thus far, no single- detector full-sky map exists of the anisotropy. Using IceCube's neutrino data, we can complement these studies with an exploration of the northern sky anisotropy at higher energies of cosmic rays. This could bring us much closer to understanding the complete picture of this anisotropy across energy levels and the whole sky. [Preview Abstract] |
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