November 30, 2017. 7:30PM. Bigelow Physics Building 102. Shane L. Larson. Whispers from the Cosmos: The Dawn of Gravitational Wave Astronomy.

The Russell Frank Astronomy Lecture Series
UNLV Department of Physics & Astronomy

Whispers from the Cosmos:
The Dawn of Gravitational Wave Astronomy

Professor Shane L. Larson
Northwestern University

We tell the story of the discovery of gravitational waves (awarded the Physics Nobel Prize this year). These waves reveal what happens when two black holes collide, how the inner core of a star destroys itself during a supernova explosion, and how the graveyard of the galaxy is filled with the whisper of binary white dwarf stars that spiral together as they fade into oblivion. We will also look ahead to the future of this new branch of astronomy.

This talk is intended for a general audience including enthusiasts of all backgrounds and ages.

November 14, 2017. 2:00PM. BPB-217. Anna Childs. Exterior Giant Planet Effects on Terrestrial Architecture.

Masters defense

Terrestrial planet formation is a chaotic and violent process which is not fully understood. Prior to Kepler, Solar System observations were the basis for planet formation models. However, Kepler observations have shown that exoplanet systems are very different from our solar system, thus requiring a more complete planet formation model. With advancements in computational ability, N-body integrators, and collision models, we can explore planet formation by experimenting with simulations in different parameter space. Our Solar System has shown us that exterior giant planets can play a vital role in the shaping of the final terrestrial planet system. Our recent N-body simulations have explored the relationship between exterior giant planets of varying mass and size, and final terrestrial planet architecture. Understanding the relationship between the presence of giant planets and terrestrial system structure will help us interpret observation, and aid in the formulation of a general terrestrial planet formation model.

November 13, 2017. 3:00PM. BPB-217. Champika Sandamali Weerasooriya. Probing Broad Line Regions of Active Galactic Nuclei.

Ph.D. Defense

The broad line regions (BLR) of Type I Active galactic nuclei are too small to be spatially resolved even with the most powerful telescopes available. Observations suggest that the BLR gas is moving under the influence of the gravitational potential of a central super massive black-hole and responds to the variations in the ionizing continuum flux of the accretion disk. The continuum flux variations cause broad emission line variations with a time delay. Reverberation mapping campaigns seek to use this time variability to resolve the BLRs in the time domain instead of spatial domain, providing a way to infer geometry and kinematics of the BLR and calculate the mass of the central black hole. Numerous BLR models have been proposed over the years but only few of them are physically motivated. In this work, we examine the feasibility of constraining the parameters of such a physically motivated model; a disk-wind model of the BLR. We employ a Bayesian inference framework to compare predicted line light curves to an observed line light curve, using simulated data. A shortcoming of reverberation mapped data is that they may contain large gaps between consecutive observations. We have implemented a method and developed a code to evenly sample observed continuum light curves. One can then carry out, using observational data, an analysis similar to the one discussed above.