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Articles 31 - 49 of 49
Full-Text Articles in Astrophysics and Astronomy
Selecting Island Pixels With A Likelihood Ratio, Jordan Tweddale
Selecting Island Pixels With A Likelihood Ratio, Jordan Tweddale
Physics
A new method, called the Log Likelihood Ratio (LLR), was employed in place of a Signal-to-Noise Ratio (SNR) to pick out signal pixels on the VERITAS (Very Energetic Radiation Imaging Telescope Array System ) telescopes. The LLR test was performed on both photoelectrons and timing for VERITAS to select island pixels in Stage 2 cleaning, which is where the camera image is processed to determine which pixels on the camera are signal, and which are background. The two LLRs were combined to form a final LLR, which has a numerical cut, LLR = 11.5, between signal and background pixels. The …
Modeling The Spectral Energy Distribution Of Mrk 421, Randall L. Oglesby
Modeling The Spectral Energy Distribution Of Mrk 421, Randall L. Oglesby
Physics
Blazars are astronomical objects thought to be powered by the release of gravitational energy by accretion of material into a supermassive black hole located in the central region of the host galaxy. Some AGN present strong relativistic outflows in the form of jets, with blazars being the particular subset whose jets are aligned with our line of sight. Even though blazars account for only a small fraction of all AGN, they are the dominant class source in the high-energy sky. In this thesis we study the spectral energy distribution of Mrk 421, a prototypical blazar. Using publicly available numerical code …
Determining Stellar Velocity Dispersion In Active Galaxies: Is The [Oiii] Width A Valid Surrogate?, Kelsi Flatland
Determining Stellar Velocity Dispersion In Active Galaxies: Is The [Oiii] Width A Valid Surrogate?, Kelsi Flatland
Physics
The tight empirical relation between the stellar velocity dispersion (sigma) of the bulge and the mass of the supermassive black hole (BH) at its center indicates a close connection between galactic evolution and BH growth. The evolution of this relation with cosmic time provides valuable clues to its origin. While the mass of the BH can be easily estimated using the Doppler broadening of the Hbeta emission line in type I active galactic nuclei (AGNs), measuring sigma simultaneously is challenging, since the nuclear emission outshines the host galaxy. Thus, it is highly desirable to find an alternative way to estimate …
Variability Studies Of Multi-Wavelength Data From Gamma-Ray Blazars Mrk 421 And Mrk 501, Brandon Becker
Variability Studies Of Multi-Wavelength Data From Gamma-Ray Blazars Mrk 421 And Mrk 501, Brandon Becker
Physics
In this thesis we take astronomical multi-wavelength data from nearby blazars Markarian 421 and Markarian 501 and perform computational analysis and correlative studies to determine any possible time lag across different bands of our targets as well as to measure the statistical significance of this calculated result. The data was taken over the interval of December 2010 to May 2012 from multiple instruments spanning a broad range of wavelengths. We used the Discrete Correlation Function (DCF) to determine the time lag factor across data set pairs, focusing on X-ray and Very-High-Energy (VHE; >100 GeV) data. To establish the significance of …
Orbital Velocities In The Broad Line Region Of Seyfert 1 Galaxies, Rebecca Renee Rosen
Orbital Velocities In The Broad Line Region Of Seyfert 1 Galaxies, Rebecca Renee Rosen
Physics
Active galactic nuclei (AGNs) are among the most energetic objects in the Universe and are believed to be powered by supermassive black holes. By studying optical spectra of these AGNs, information can be acquired about the central black hole and its surroundings. Specifically the broad component of the Hβ emission line can be used to find the velocity of gas in the broad line region, a necessary step in determining the mass of the central black hole. In this thesis, I present the results of using a python code to measure the broad component of Hβ in the spectra of …
Optimization Of The Veritas Orbit-Mode Tracking Pattern, Joshua Allen
Optimization Of The Veritas Orbit-Mode Tracking Pattern, Joshua Allen
Physics
Gamma-ray Bursts (GRBs) have not been detected at TeV energies. Detection with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) would open a new window into GRB science. In this paper, we optimize an orbit mode tracking method to search for a GRB at a location provided by the FERMI Gamma-ray satellite. Using Matlab we modeled the orbit tracking pattern. Then we found the optimal offset radii and tracking speed for the telescope to form a uniform image exposure. To optimize the pattern, the model accounts for the maximum 1°/s speed of the telescope’s tracking motors and the camera’s …
Astronomical Spectroscopy At The Cal Poly Observatory, Christopher James Almich
Astronomical Spectroscopy At The Cal Poly Observatory, Christopher James Almich
Physics
Embarking on the first ever astronomical spectroscopy project at the Cal Poly Observatory, I have tested the capabilities of our equipment. Our spectrograph, in conjunction with a telescope and CCD camera, is capable of making fairly precise measurements of absorption and emission lines with sub-nanometer precision. In my research I obtained a spectrum of Jupiter and was able to confidently identify a number of Fraunhofer solar absorption lines.
Analysis Of The 2008 Flare Of Markarian 421 Flare With Veritas, Casey Allard
Analysis Of The 2008 Flare Of Markarian 421 Flare With Veritas, Casey Allard
Physics
A theoretical light curve model is fit to an observed short term flare of Markarian (Mrk) 421 in the very high energy spectrum. The flare is characterized by its measured light curve from the Very Energetic Radiation Imaging telescope Array System (VERITAS). The flare we analyzed occurred in May 2008. We successfully fit a theoretical model to the Mrk 421 data light curve. The data appears to agree with the Wagner [1] and Salvati [2] models. These models appear to fit both broad and sharp flaring regions found in the measured light curve. Furthermore the Wagner model is used to …
A Brief History And Research Of The Supernova Remnant Cassiopeia A, Michelle Wilbur
A Brief History And Research Of The Supernova Remnant Cassiopeia A, Michelle Wilbur
Physics
No abstract provided.
Exoplanet Transit Detection With Terrestrial Amateur Equipment: Using The Cal Poly Observatory, San Luis Obispo, Joshua Thompson
Exoplanet Transit Detection With Terrestrial Amateur Equipment: Using The Cal Poly Observatory, San Luis Obispo, Joshua Thompson
Physics
Using amateur level equipment and freeware analysis tools, the Cal Poly Observatory (CPO) wished to test whether or not it could actually observe the astronomical phenomena called exoplanetary transits. Using a variety of equipment and tests, the CPO was able to confirm it could clearly observe the transits of several well-known transiting planets, including HD189733b and HAT-P-6. With these tests and observations completed, future student researchers can continue Cal Poly’s transit search and contribute to the global pursuit for exoplanets.
Determining Pulsation Period For An Rr Lyrae Star, Leah M. Fabrizio
Determining Pulsation Period For An Rr Lyrae Star, Leah M. Fabrizio
Physics
No abstract provided.
Survey Of Meteorite Samples For 92nb, 98tc, And 60fe Using Gamma Ray Spectroscopy, Robert Maxwell
Survey Of Meteorite Samples For 92nb, 98tc, And 60fe Using Gamma Ray Spectroscopy, Robert Maxwell
Physics
The focus of this senior project was the use of gamma ray spectroscopy to survey meteorite samples for 92Nb, 98Tc, and 60Fe. The presence of measurable amounts of 26Al (half-life 717,000 years) in meteorites leads astrophysists to believe that 92Nb, 98Tc, and 60Fe should also be present in detectable amounts, though they have not yet been conclusively found. Since the isotopes that were looked for in this senior project are not long lived in comparison to the age of the solar system, their presumed presence indicates that they are continuously being made in outer space and deposited on space objects.
Analysis Of The Blazar 1es1218+30.4, Timothy Wolf
Analysis Of The Blazar 1es1218+30.4, Timothy Wolf
Physics
I analyzed the Blazar 1ES1218+30.4 in the high energy spectrum with VERITAS telescope data. The analysis used improved the energy spectrum obtained for the blazar from a maximum of 2.49 TeV to 3.85 TeV. The flux for this point is greater than the previous fit equation predicts, indicating a possible shoulder in the EBL, or Extragalactic Background Light.
Study Of Accretion Effects Of Transients In Lmxb System, Quentin Lamicq
Study Of Accretion Effects Of Transients In Lmxb System, Quentin Lamicq
Physics
Neutron stars are intriguing stellar laboratories that are very exciting to study due to the presence of matter in an extreme state. The luminosity of some neutron star transients in low mass X-ray binary (LMXB) systems is known to have quiescent intervals that may be affected by the rate and duration of accretion from the companion star onto the neutron star. We refined a model of the luminosity of the neutron star to allow for possibility that the accretion rate declines at a steady rate until it reaches zero. After a neutron star goes through an outburst, the quiescent period …
A New Technique For Detecting Cosmic Strings In The Cosmos Survey Using Shapelet Decomposition, Kevin A. James
A New Technique For Detecting Cosmic Strings In The Cosmos Survey Using Shapelet Decomposition, Kevin A. James
Physics
The Hubble Space Telescope Treasury Program images collected as part of the Cosmic Evolution Survey were used to develop a new technique for identifying gravitational lensing events resulting from a less-massive cosmic string. By employing Monte Carlo simulations of cosmic strings embedded within the survey, galaxies were decomposed using Hermite Polynomial shapelets, and compared with the unaltered survey. An efficient set of cuts were determined for identifying a cosmic string in shapelet space. The sensitivity of the new methodology was found to be superior at detecting low-mass cosmic strings than previous methods.
Extrasolar Planet Detection Through Analysis Of K-Giant Radial Velocity Data, Floyd D. Linayao
Extrasolar Planet Detection Through Analysis Of K-Giant Radial Velocity Data, Floyd D. Linayao
Physics
Extrasolar planet detection is an ongoing and growing field of scientific research. To date, there are over 400 planet candidates discovered by various means of detection. Currently, astronomers taking observations at Lick Observatory are searching for potential extrasolar planets around K-giant stars. The project was originally developed to monitor stars to be used in the astrometric grid for NASA’s Space Interferometry Mission (SIM). While using the radial velocity method to test if the astrometric centers of K-giants were stable, astronomers came to the realization that the same process could be used for extrasolar planet detection. Of the 373 K-giants being …
Central Compact Objects, Trevor Meek
Central Compact Objects, Trevor Meek
Physics
Central compact objects (CCOs) are point-like sources found near the center of supernova remnants (SNRs). They emit X-rays, but show no radio or gamma ray counterpart. Typical CCO candidates have emission radii on the order of 0.2-3.0 km. This is much smaller than the typical radius of a neutron star, making CCOs a difficult astronomical phenomenon to identify.
Gamma-Ray Spectroscopy: Meteorite Samples And The Search For 98tc, Kristopher L. Merolla
Gamma-Ray Spectroscopy: Meteorite Samples And The Search For 98tc, Kristopher L. Merolla
Physics
The focus of this project is low-count-level gamma-ray spectroscopy on meteorite samples in search of a particular isotope of Technetium (98Tc), which according to stellar theory, should be present in the universe. The spectral lines for 99Tc have, however, been observed in S-, M-, and N- type stars, which makes finding 98Tc created naturally a possibility, and thus a search can be justified.
The Greenhouse Effect: Common Misconceptions And Effective Instruction, Trevor W. Strickland
The Greenhouse Effect: Common Misconceptions And Effective Instruction, Trevor W. Strickland
Physics
This study is an extension of the research of Dr. John Keller. It attempts to identify common student misconceptions regarding the greenhouse effect and investigate instructional methods of teaching the greenhouse effect. Dr. Keller developed a test, known as the Greenhouse Effect Concept Inventory (GECI), designed to measure a student’s understanding of the greenhouse effect. A central goal of this project is to investigate the effectiveness of this concept inventory at measuring differences in student knowledge of the greenhouse effect. In addition to the Cal Poly student population that participated in this research, we will be looking at the population …