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In Steinmetz Symposium

Abstract

Following the research done on primordial black holes, initially by Steven Hawking and Bernard Carr in 1974, there has been extensive research in the field of Cosmology regarding primordial black holes. My goal was to compile and analyze the research and investigate several areas of Astronomy and Cosmology to see where primordial black holes could offer some insight into unanswered questions in the fields. I studied the relationship between primordial black holes and quasars, galaxy formation, dark matter, and observed gamma ray bursts. I also mathematically derived equations to verify the conclusions made by Hawking and Carr in their 1974 paper. I found that, primordial black holes should also have formed in the early, radiation-dominated universe given any slight over-density of matter.

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DigitalDocument

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Controlled Access Terms

In Honors Theses

Abstract

Compact symmetric radio galaxies (known as compact symmetric objects, or CSOs) are believed to be the very young versions of the classical double-lobed radio galaxies, and are known to have radio spectra which peak at GHz frequencies. The downturn in their spectra at lower frequencies must be due to some absorption mechanism – either by free-free (f-f) absorption by line-of-sight electrons in the host galaxy, or synchrotron self-absorption (SSA) by electrons within their jets. We present the results of our analysis of high resolution observations made with Very Long Baseline Interferometry at six frequencies of two CSOs, 0026+346 and 1321+410, including models of their absorption spectra at high spatial resolution. An extrapolation of the optically-thin high-frequency images are compared with the low-frequency images to obtain maps of optical depth, and the spectral shape of the absorption regions are fit to models of f-f absorption versus SSA. For 1321+410 we find that the observed spectral shape does fit well with a simple single-component f-f absorption model while the spectrum of 0026+346 does not. Assuming SSA is the primary absorption mechanism in 0026+346, we determine an upper limit on the strength of the magnetic field in the core of this galaxy at a radius of 0.02±0.01 parsecs (6±3×1011 km) to be Gauss.

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Thesis

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In Honors Theses

Abstract

As the European Space Agency prepares to launch the space telescope Euclid in 2020, we are interested in using its observations of galaxy clustering as a new geometry-based tool to constrain the cosmological parameters ?m and ??. In this work, we use data simulated by Magneticum (a high-resolution cosmological structure simulation) to model the correlation functions of both galaxies and clusters at several redshifts. We fit analytic models to the simulated data centered at the baryon acoustic oscillation peak to extract both the matter density parameter ?m and the dark energy density parameter ??: We find that the correct cosmology is within the 68% confidence interval for both galaxies and clusters of galaxies.

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Thesis

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In Honors Theses

Abstract

To better understand the properties of high redshift galaxies and improve models of galaxy formation, we are investigating color radial pro?les to study the stellar age, dust and metallicity distribution of galaxies of varying lumi-nosities and morphological types. Current data obtained in the optical and UV have shown that early-type galaxies have a ?at color pro?le, or are bluer at larger radii, while late-type spirals are redder with increasing radius. These trends are believed to be linked with stellar population ages or dust. To break the age-dust degeneracy as well as to avoid the metallicity dependence, we have obtained near-infrared images of Nearby Field Galaxy Survey (NFGS) galax-ies taken with the PISCES Wide-?eld Infrared Camera on the 90-inch Bok Telescope. Combined with the optical and UV data, these new, near-infrared images will help better constrain these parameters and determine the ages of the stellar components of the galaxies. We discuss the method used to process and reduce the data and present the radial pro?le of the surface brightness and color of one particular galaxy in the sample, UGC 439.

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In Honors Theses

Abstract

Observations of the globular cluster IC4499 were taken with the 1m telescope at Cerro Tololo and combined with archival data from multiple telescopes. These data were used to study the variable star population using CCD photometry, with observations in the U, B, V, R and I passbands. The period and the magnitudes have been measured for the RR Lyrae stars. We present light curves in all passbands for all 97 RR Lyrae stars. The magnitudes of the RR Lyrae stars are compared with those measured by Walker and Nemec (1996). The distribution of stars on the horizontal branch is compared with estimates from theoretical models, and we confirm the horizontal branch color limits to the instability strip reported by Walker and Nemec.

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In Honors Theses

Abstract

High-precision kinematics of individual stars in Milky Way satellite galaxies and globular clusters is crucial for studies of galaxy formation, cosmology, alternative gravity models, and dark matter. We tested a rigorous method that matches model DEIMOS observations of such targets with synthetic template spectra that deduces radial velocities and [Fe/H] abundances. We added noise to create a model spectrum with SNR = 30, fitted templates with different parameters to it, and calculated the<br />best-match velocity and the goodness of the fit. The best fits occur for templates that are close in parameter space to the model spectrum, and the fits get worse the further away the templates are from the model spectrum. Within a window of ? ±1500 K from the model spectrum, the bias in inferred velocity increases at a rate of roughly ? 0.5 km s?1/1000 K , but stays below the DEIMOS resolution. We conclude that the method does not introduce a bias to the inferred velocity larger than ? 30% of the instrumental resolution and that the uncertainty is dominated by the resolution, suggesting that the step size in our parameter space was well chosen.

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Thesis

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In Alumni Files

Type of Resource

DigitalDocument

In Alumni Files

Type of Resource

DigitalDocument