Other Physics Commons^™

Modeling Velocity Distributions Of Interstellar Neutral Hydrogen In The Heliosphere, Lucas Robert Dyke

Dartmouth College Ph.D Dissertations

As interstellar neutral hydrogen (ISN H) is the most abundant neutral element in the helio- sphere, the region within which the solar wind interacts with the portion of the interstellar medium through which our solar system moves through, it is integral that we aim to under- stand its many properties and interactions within this region. This work details the synthesis and use of a model of ISN H, using trajectory methods to backtrace from a target point at a radial distance of 1 au where explorer probes like Interstellar Boundary Explorer (IBEX) and Interstellar Mapping and Acceleration Probe (IMAP) reside. …

Computational Modeling Of Astrophysical Systems, Leleya Iris Stallard

Spring Showcase for Research and Creative Inquiry

This research project focuses on the computational modeling of astrophysical systems using Femap with NX Nastran. The goal was to simulate and analyze the vibrational behavior and structural deformation of celestial bodies under different material compositions and collision conditions. Materials such as iron, granite, titanium, and models for white dwarf stars were used to investigate how varying physical properties affect the systems' dynamic responses. Both isotropic and anisotropic models were created to represent realistic astrophysical materials. Through static and modal analyses, the study explored how internal structure and material stiffness influence the reaction of celestial objects to applied forces and …

Stability Of A Regular Black Holes Thin-Shell Wormhole In Reissner-Nordstrom - De Sitter Space-Time, A. Eid

Applications and Applied Mathematics: An International Journal (AAM)

The dynamics regular black holes thin shell wormhole with a phantom energy equation of state in Reissner-Nordstrom - De sitter space-time is studied using the Darmois-Israel formalism. A mechanical stability analysis is carried out by using the standard perturbation method. The stable and unstable static solution depends on the suitable value of parameters.

Gamma/Hadron Separation For The Hawc Observatory, Michael J. Gerhardt

Dissertations, Master's Theses and Master's Reports

The High-Altitude Water Cherenkov (HAWC) Observatory is a gamma-ray observatory sensitive to gamma rays from 100 GeV to 100 TeV with an instantaneous field of view of ~2 sr. It is located on the Sierra Negra plateau in Mexico at an elevation of 4,100 m and began full operation in March 2015. The purpose of the detector is to study relativistic particles that are produced by interstellar and intergalactic objects such as: pulsars, supernova remnants, molecular clouds, black holes and more. To achieve optimal angular resolution, energy reconstruction and cosmic ray background suppression for the extensive air showers detected by …

A Model Of So-Called "Zebra" Emissions In Solar Flare Radio Burst Continua, R. A. Treumann, R. Nakamura, W. Baumjohann

Dartmouth Scholarship

A simple mechanism for the generation of elec- tromagnetic “Zebra” pattern emissions is proposed. “Zebra” bursts are regularly spaced narrow-band radio emissions on the otherwise broadband radio continuum emitted by the ac- tive solar corona. The mechanism is based on the generation of an ion-ring distribution in a magnetic mirror geometry in the presence of a properly directed field-aligned electric po- tential field. Such ion-rings or ion-conics are well known from magnetospheric observations. Under coronal condi- tions they may become weakly relativistic. In this case the ion-cyclotron maser generates a number of electromagnetic ion-cyclotron harmonics which modulate the electron maser …

Modeling Weak Gravitational Lensing Through C++, Christopher Cepero

Undergraduate Review

Gravitational Lensing has become an integral part of astrophysics and the study of matter in the universe. In weak gravitational lensing, an object appears distorted when viewed from the observer’s perspective. This is caused by the bundle of light being distorted by an object of considerable mass. Because the distance to each part of this bundle is not the same, the rays of light are affected differently causing a shearing and magnification of the image. This alteration in the image we see can be modeled using the thin lens approximation. By integrating the equations for light travel based on general …

High Resolution Studies Of Complex Solar Active Regions, Na Deng

Dissertations

Flares and Coronal Mass Ejections (CMEs) are energetic events, which can even impact the near-Earth environment and are the principal source of space weather. Most of them originate in solar active regions. The most violent events are produced in sunspots with a complex magnetic field topology. Studying their morphology and dynamics is helpful in understanding the energy accumulation and release mechanisms for flares and CMEs, which are intriguing problems in solar physics.

The study of complex active regions is based on high-resolution observations from space missions and new instruments at the Big Bear Solar Observatory (BBSO). Adaptive optics (AG) in …