December 8, 2017. 3:30PM. Bigelow Physics Building 102. Ho-kwang Mao. Solids, Liquids, and Gases Under High Pressure.

Pressure has long been recognized as a fundamental thermodynamic variable, but its application was previously limited by the available pressure vessels and probes. The development of multi-megabar pressure vessels and a battery of associated in-laboratory and synchrotron techniques at the turn of the century have opened a vast new window of opportunities. With the addition of the pressure dimension, we are facing a new world with an order of magnitude more materials to be discovered than all that have been explored at ambient pressure. Pressure drastically and categorically alters all elastic, electronic, magnetic, structural, and chemical properties, and pushes materials across conventional barriers between insulators and superconductors, amorphous and crystalline solids, ionic and covalent compounds, vigorously reactive and inert chemicals, etc. In the process, it reveals surprising high-pressure physics and chemistry and creates novel materials. I will describe the principles and methodology used to reach ultrahigh static pressure, the in situ probes, the physical phenomena to be investigated, the long-pursued goals, the surprising discoveries, and the vast potential opportunities. Examples include the recent advances and surprising findings in high-pressure research of hydrogen, oxygen, iron, and carbon. Overall, this review demonstrates that high-pressure research is a new dimension in physics, chemistry, Earth and materials sciences.

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.

September 14, 7:00PM Bigelow Physics Building, BPB-102. University Forum Lecure: Mario Livio on Human Curiosity.

Human Curiosity

Thursday, September 14 - 7:00 PM Bigelow Physics Building, BPB 102
Please note the location change.

Mario Livio
Internationally known astrophysicist and bestselling author

The ability to ask "why?" makes us uniquely human. Curiosity drives basic scientific research, is the engine behind creativity in all disciplines from the arts to technology, and a necessary ingredient in every form of storytelling (literature, film, TV, or even a simple conversation) that delights rather than bores. In a fascinating and entertaining lecture, renowned astrophysicist and author Mario Livio surveys and interprets cutting-edge research in psychology and neuroscience that aims at exploring and understanding the origin and mechanisms of human curiosity. As part of his research into the subject, Livio examined in detail the personalities of two individuals who arguably represent the most curious minds to have ever existed: Leonardo da Vinci and Richard Feynman. He also interviewed 9 exceptionally curious people living today, among them linguist Noam Chomsky and the virtuoso lead guitarist of the rock band Queen, Brian May (who also holds a PhD in astrophysics), and presents fascinating conclusions from these conversations

Co-sponsored by the Department of Physics and Astronomy

Prof. Livio is an Adjunct Professor in Physics & Astronomy at UNLV. He is the author of numerous books and academic papers, including his latest: Why? What Makes Us Curious. Simon & Schuster. 2017. ISBN 978-1476792095. He was interviewed recently on NPR's Talk of the Nation Science Friday.

August 21, 2017. 9:00AM. BPB roof. UNLV Physics & Astronomy Eclipse activity.

The Aug 21, 2017 Eclipse

Around 9:00AM we'll set up a couple telescopes on the Bigelow Physics Building roof. The scopes will project an image of the Sun onto screens that can be safely viewed. We'll live stream one of the screens on to the net. The URL is: https://www.twitch.tv/horizonsci/

The scopes will be up from about 9AM to 12 noon which spans the whole eclipse maximum which will be at about 10:30 with 72 % coverage.

Drs. David Jeffery and Jason Steffen will be around to answer questions and demonstrate pinhole projection. Other students, faculty, and staff may also be on site to answer questions.

Postscript

Obviously, we didn't have an optimal day for viewing the eclipse in Las Vegas as a storm front moved through the valley. However, some time around 10:30AM clouds began clearing, glasses came out, a telescope was hastily set up and we had some quite good viewing from the roof and the area surrounding Bigelow Physics with "pinhole effects" from the tree canopy. Some images:

August 18, 2017. 2:00PM. BPB-217. Timothy Waters. Properties, Dynamics, and Spectral Signatures of Clouds in AGN.

Ph.D. Defense

Understanding the high-pressure behavior of transport properties has been a driving force in the study of materials under extreme conditions for well over a century being pioneered by P.W. Bridgman in the early 20th century. Research dedicated to the study of these properties leads to a variety of important applications: exploration of insulator to semi-conductor to metal structural and electronic phase transitions, correlation of structural phase transitions and the electronic properties along phase boundaries, testing validity of theoretical models, understanding the effects of chemical pressure, among a slew of other applications. This work has designed and developed a specialized sample cell assembly for use with a Paris-Edinburgh press capable of performing high-pressure and high-temperature (HP-HT) electrical resistance, Seebeck coefficient, thermal conductivity measurements alongside energy-dispersive X-ray diffraction and X-ray radiography imagining up to 6 GPa and 500�C to fully characterize the electrical, thermal, and structural properties of materials simultaneously at extreme conditions. This system has been installed at Argonne National Laboratory at the Advanced Photon Source at the Sector 16 BM-B beamline of the High-Pressure Collaborative Access Team and is now available to general users as a measurement technique. Application of this system has been applied to thermoelectric materials: PbTe, SnTe, TiCoSb, and TiNiSn. Thermoelectric materials provide a valuable means of converting waste heat into useful electrical energy and studying their HP-HT properties allows a better understanding and identification of greater efficiency through tuning of transport properties. The detailed discussion of the design and development of this system alongside the important results on the thermoelectric materials mentioned will be presented in this dissertation.