February 11, 2016 3:30 BPB-217. Candidate: Norbert Werner. Sculpting the Visible Universe.

In the course of structure formation, only a small fraction of the baryons turned into stars - most remain in a diffuse intergalactic medium. The growth and evolution of galaxies is controlled by feedback processes, such as energy and momentum input from supernovae, and from the jets and winds of accreting supermassive black holes. I will start my talk by presenting observational results on the role of supermassive black holes in suppressing star formation in the most massive galaxies, keeping them 'red and dead'. Then, I will show how deep observations of extreme clusters of galaxies inform us about the microphysics of the intergalactic medium, which determines how the energy from accreting black holes couples with the diffuse gas. Then, I will 'zoom out' to the outskirts of galaxy clusters where we also find hints that supermassive black holes played an important role in the distant past. X-ray observations reveal a remarkably homogeneous distribution of iron out to the virial radius of the nearby Perseus Cluster, requiring that most of the metal enrichment of the intergalactic medium occurred before the cluster formed, probably more than ten billion years ago, during the period of maximal star formation and black hole activity. Finally, I will talk about the upcoming ASTRO-H satellite which will revolutionize X-ray spectroscopy and our understanding of the physics of galactic feedback.

Jared Rice wins NVSGC Graduate Research Fellowship

Jared Rice was awarded a prestigious Nevada NASA Space Grant Consortium Graduate Research Opportunity Fellowship in the amount of $21,000 for the 2015/2016 academic year. The NVSGC GROF supports Jared and his advisor Dr. Bing Zhang on their latest project on the characteristics of high-redshift tidal disruption events. Their proposal entitled "Tidal Disruption Events in the Early Universe" was selected by NVSGC as one of the top applications of the year across the state of Nevada. The fellowship is a 1:1 match from NVSGC and the UNLV Department of Physics and Astronomy. More details may be found on the NVSGC fellowship recipients page:

2015-2016 Fellowship Recipients

February 12, 2016 3:30PM BPB-207. Shanti Deemyad. Lithium under pressure.

Even at zero temperature lattice of lithium remains far from static. In periodic table lithium is the first element immediately after helium and the lightest metal. While fascinating quantum nature of condensed helium is suppressed at high densities, because of the presence of long range interactions in metallic systems, lithium is expected to adapt more quantum solid behavior under compression. Physics of dense lithium offers a rich playground to look for new emergent quantum phenomena in condensed matter. In this talk I will discuss the physics of ultra-light materials under extreme pressures and will present some of our studies on unraveling the physics of dense lithium.

February 5, 2016 3:30PM BPB-207. Rebekah Dawson. All Planets Great and Small.

Discoveries of exoplanets so different from those in our Solar System have called in question conventional theories for how planetary systems form and evolve. I will present recent progress in our understanding of the physical processes that drive the assembly of planetary systems and result in the surprising variety of orbital architectures we observe today. I will discuss orbital evolution in both the large and small planet regime and physical processes that link planetary orbits to their physical properties and properties of their host stars.

January 29, 2016 3:30PM BPB-207. Joseph M. Zaug. Ultrafast Shock Compression Experiments to Rapidly Test Extreme Condition Materials Predictions.

In this talk, we will discuss recent results from ultrafast tabletop laser compression experiments on fluids, polymers, and high energy density organic molecules including single crystals. Previous work on ultrafast shocked metals will be summarized and serve as an introduction to our technical approach. Extreme material theories benefit from this research through a growing understanding of how ultrahigh strain rate (10⁸ -10¹¹ s^-1) loading processes affect later-time high-strain rate (10⁴ -10⁶ s^-1) phenomena occurring on macroscale dimensions.

Larger scale gun-based compression platforms nominally generate 10⁶ s^-1 maximum equilibrated strain rate loads; however, initial rising transient strain rates —not measured— may actually reach ultrahigh values. At present, the ultrafast shock community currently utilizes diagnostics that measure hydrodynamic flow and UV/VIS absorption; however, these methods tell us nothing directly about structure or chemical states. (We can consider perspectives on the viability of potential solutions to this long-standing challenge.) Nonetheless, when we’ve matched —on identical temporal and spatial scales— hydrodynamic data with commensurate molecular dynamics or crystal mechanics simulation results, more comprehensive pictures materialize that further illuminate the progression of early-time shock induced phenomena, such as high-strain rate induced elastic to plastic wave transitions preceding chemical initiation. Definitive knowledge gaps are also discovered.

We will conclude this presentation with an example of how one may use ultrafast compression-quench experiments to freeze metastable intermediate products. Shockwave compression states normally release to high-temperature thermodynamic states governed by the heat capacity of the starting material; however, by stopping (at an early-stage) shock induced chemical decomposition, i.e., bond breaking, one can trap or even consider synthesizing previously inaccessible transient species. For example, diamond formation from shocked TATB (1,3,5-triamino-2,4,6-trinitrobenzene) had been predicted for decades and was finally proved correct using this novel experimental approach.

Dr. Joseph (Joe) Zaug - Founding member (1997) and leader of the High Pressure Chemistry Group within the Materials Sciences Division at Lawrence Livermore National Laboratory. (Ph.D. in Physical Chemistry, University of Washington, Seattle, 1994; B.S. in Chemistry, Illinois Institute of Technology, 1988) He has twenty-five years of experience developing tools that quasi-statically and/or dynamically compress materials and engineering new approaches to characterize extreme condition material response using primarily laser-based systems. Numerous grand-challenge science issues have been met by these innovations resulting in high-profile publications in disciplines such as geophysics, high-pressure physics and chemistry including chemical synthesis, and materials science. Joe and his group actively collaborate with international and U.S. collaborators. His current research focus is on measuring equations of state and physical or chemical phase transitions of single crystals, polymers, and composite materials subjected to quasi-static and ultrahigh strain rate loads. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

January 22, 2016 3:30PM BPB-207. David Radice. Turbulent Lives: Tales of Neutron Stars.

Neutron stars live interesting and mysterious lives: from the moment they are created in core-collapse supernovae, to the moment some of them eventually collapse to black-holes. In this talk, I will cover some aspects of their lives. I will discuss their birth in core-collapse supernovae, focusing on the key role of hydrodynamic turbulence in triggering the explosion, and their death in neutron star mergers. Finally, I will present recent results on the outcome of the dynamical ejection of neutron-star matter that might take place during mergers.

January 6, 2016. Jason Steffen on NPR's Marketplace.

Jason Steffen (Physics and Astronomy) was a guest on NPR's Marketplace, talking about how to more efficiently board an airplane. He began researching the issue as a graduate student after being frustrated by slow boarding processes and flight delays.

The press release from UNLV:

Jason Steffen News Center