Department of Physics

Will Advanced LIGO Deliver?

After a decade of operations the Laser Interferometer Gravitational Wave Observatory's detectors in Hanford, Washington and in Livingston, Louisiana, have been decommissioned. A feverish construction process has started to upgrade the observatories with new detectors. In this talk I will review the science developed with initial LIGO, particularly the latest results obtained with so-called scientific run 6 which ended October 20, 2010,  and describe the promise and prospects of the science to be developed with Advanced LIGO.

First Look at the Data from the Large Hadron Collider at the European Lab for Particle Physics

The Large Hadron Collider has delivered its first data of the highest energy to the experiments at the European Lab for Particle Physics  (CERN). Early results reported by the Atlas, CMS and LHCb experiments will be presented and discussed. The focus will be on the observation of beauty hadrons and charmonium states, the performances of the detectors, and the ‘rediscovery’ of the Standard Model of elementary particle physics. Prospects for major discoveries with the experiments at the LHC will also be discussed.

Electrical and magnetic properties of epitaxial (SrMnO3)n / (LaMnO3)2 superlattices

Nowadays, new technologies in thin films fabrication allow growing oxides by a single unit cell layer deposition , unraveling new and exciting scenarios in the study of the interface effects in multilayers and heterostructures. A variety of interesting and unexpected electronic and magnetic phenomena have been observed at the interfaces between different oxides.The role of the charge transfer across those interfaces has been actively studied in recent years. In this context, (SrMnO3)n/(LaMnO3)2n superlattices consisting of n planes of SrMnO3 alternated by 2n planes of LaMnO3 show a remarkable interfacial modification of the bulk properties of the two constituent materials. Although SrMnO3 and LaMnO3 are insulators, (SrMnO3)n/(LaMnO3)2n superlattices can exhibit metallic properties. Dynamical Mean Field theory calculations have suggested that the metallic behavior nucleates from an electronic reconstruction at the interface and that the charge transfer effects extend deeply in the layers away from the interfaces, thus leading to original electronic and magnetic properties of the superlattices as a whole. In this context, (SrMnO3)n/(LaMnO3)2n superlattices are of particular interest because exhibit the same La/Sr stoichiometry ratio (i.e., Mn3+/Mn4+) as La2/3Sr1/3MnO3, the optimally doped Sr-based manganite. Nevertheless, in bulk La2/3Sr1/3MnO3 La/Sr A-sites are randomly populated resulting in a disordered Coulomb trapping potential, whereas in (SrMnO3)n/(LaMnO3)2n superlattices an ordered sequence of SrMnO3 and LaMnO3 planes occurs. As a consequence the Mn3+/Mn4+ mixed valence arises only on the interfacial MnO2 planes, which are thus ferromagnetic (FM) and metallic (M) as opposed to the individual constituent blocks, where the MnO2 planes are antiferromagnetic (AF) and insulating (I).

Measuring Mass in the Universe Using Gravitational Lensing

Astrophysical observations are consistent with a universe where most of the matter is cold and dark, and where the even more mysterious dark energy dominates the total energy density. Thus most of our universe is not directly observable using telescopes.In my talk, I describe the signatures of gravitational lensing by different structures in the universe, focusing on how we measure and map the mass in galaxy clusters. I discuss how these results test our cosmological paradigm, and also help us to understand the physical processes in the most massive objects in the universe. As well as describing some current observations, I outline the bright prospects for these studies in near-future surveys. My talk then zooms out from galaxy clusters to the large-scale structure of the universe, and I conclude by outlining our framework to predict the potential observational signatures of exotic physics in future surveys.

Counting Giants: Cosmology from Massive Sunyaev-Zel'dovich Galaxy Clusters

We have reached the era where microwave surveys such as the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) are reporting the first samples of massive galaxy clusters through the Sunyaev-Zel'dovich (SZ) effect. In this talk I will introduce the set of optically-confirmed galaxy clusters discovered by ACT through the SZ effect as well as our ambitious program to identify and characterize the galaxy clusters using a plethora of multi-wavelength observations. Using counts of galaxy clusters as a function of mass and redshift in this sample I will try to demonstrate that clusters provide a powerful probe of structure growth and cosmology. I will present the latest constraints on the matter power spectrum amplitude, sigma8, and dark energy equation of state, w, from SZ cluster counts detected with ACT.

Astronaut Michael Massimino: Fixing the Hubble

UTD is proud to announce the appearance on April 6 at 4pm of veteran astronaut Michael Massimino. He is famously associated with two crucial space walk repair missions to the Hubble telescope – Columbia in 2002 and finally Atlantis in 2009. The Hubble space telescope, weighing 25,000 pounds and orbiting the earth in a 350 mile orbit in crystal clear space, is well out of earth’s turbulent and distorting atmosphere. It is one of NASA’s crowning achievements, leading to an unprecedented photographic mapping of deep space. Problems including the 2003 Columbia disaster led to the cancellation of the project between 2003 and 2006, but incredible feats of repair finally restored the Hubble to its planned capacity – and much more. (For those who would like a preview, Mike will be interviewed by KERA’s Krys Boyd on “Think” – 90.1 - at 1pm that day.) Mike will discuss his experiences in space. Please join us for the exciting talk. There will be an autograph session afterwards.