Special Seminar: Wednesday, 16 November 2016

TBA

Speaker: Dr. Christine Jones (Harvard / AAS President)
Location: OPB 234, 2:30pm
Abstract: TBA

This is the last seminar of the Fall 2016 Semester.

Tuesday, 8 November 2016

TeV Gamma-ray Survey of our Universe

Speaker: Dr. Michele Hui (NASA MSFC)
Location: OPB 234, 2:30pm
Abstract: The High Altitude Water Cherenkov (HAWC) Observatory is an all-sky surveying instrument that covers 2/3 of the sky in 24 hours. It is located in Sierra Negra, Mexico at an elevation of 4,100 m and was inaugurated in March 2015. In addition to providing continuous sky coverage for transient events with a >95% duty cycle, HAWC is also well suited to measure extended and large-scale structures. The array consists of 300 water Cherenkov detectors and is sensitive to extensive air showers triggered by cosmic rays and gamma rays from 100GeV to 100TeV. I will present the results of HAWC’s first year of data, highlighting several TeV discoveries among the numerous supernova remnants and pulsar wind nebulae seen in the Galactic plane. I will also discuss HAWC’s transient search for active galactic nuclei flares, gamma-ray bursts, and gravitational wave counterparts.

Tuesday, 1 November 2016

Dispersion-Enhanced Cavities and Interferometers for Sensing Applications

Speaker: Dr. David Smith (NASA MSFC)
Location: OPB 234, 2:30pm
Abstract: In recent years media with steep frequency dispersions have been developed which enable an unprecedented level of control over the group velocity of light. The propagation of pulses can be slowed down, sped up, stopped, or even reversed within these materials. These effects are now moving beyond the stage of intellectual curiosity, prompting studies into a variety of exciting applications. For example, materials that can slow light have the potential to increase the resolving power of spectral interferometers without increasing their size. A fast light medium, on the other hand, can increase the sensitivity of an optical cavity to changes in optical path length, which may be exploited for the improvement of gyroscopes and accelerometers. In this talk I will review some of our experimental efforts along these lines.

Tuesday, 25 October 2016

Probing AGN Feedback in the Most Massive Cosmic Laboratories

Speaker: Dr. Rebecca Canning (Stanford Kavli Institute)
Location: OPB 234, 2:30pm
Abstract: SMBHs lurk in the centers of all massive galaxies, a fraction of these SMBHs are actively accreting and this can result in powerful outbursts which have important consequences for galaxy formation and evolution. However, the conditions under which a SMBH becomes active and the manner in which it interacts with its environment are not well understood. Clusters of galaxies offer us wonderful cosmic laboratories in which we can observe these processes. I will discuss what observations of these massive galaxy clusters can tell us about the role of AGN feedback in both maintaining a delicate balance between heating and cooling and in searching for a casual link between SMBH and galaxy co-evolution.

Tuesday, 18 October 2016

Characterizing the Role of Internal Versus External Processes in the Mass Build-up and Star Formation History of Galaxies

Speaker: Dr. Preethi Nair (UA Physics & Astronomy)
Location: OPB 234, 2:30pm
Abstract: Galaxy growth is thought to occur through a combination of both internally and externally driven processes. However, the relative role and contribution of each process is not well constrained. The main driver of internal evolution in disk galaxies are expected to be stellar bars which can drive gas into the centers of galaxies, trigger episodes of star formation as well as active galactic nuclei and lead to the build up of the central spheroidal component in galaxies. The main external drivers of evolution are mergers with other galaxies. By using large samples of galaxy pairs and visually classified bars from the Sloan Digital Sky Survey (SDSS), we compare the relative efficiency of gas inflows from these two processes. We further study the evolution of the importance of both processes using data from the Hubble Space Telescope COSMOS survey.

Tuesday, 11 October 2016

Fabrication and Characterization of Fiber Optic Imaging Devices

Speaker: Dr. Shuqin Zhang (Jiliang University)
Location: OPB 234, 2:30pm
Abstract: Fiber optic imaging devices (FOID), such as fiber optic plates (FOP), fiber optic inverter (FOI) and fiber optic taper (FOT), are key components of the image intensifiers that form the core of low-light-level (LLL) night vision. Advanced preparation technologies including rod making, fiber drawing, and the heating and pressing processes have been investigated, focusing on innovative approaches that lead to FOID with high resolution, low distortion and high transmission efficiency. Key equipment such as FOI reversing devices and FOT drawing control devices is successfully developed, and the optimization of related process is achieved. At the same time, tracking evaluation enables the research of systematic evaluation of fiber-optic imaging elements preparation technology and key properties. In order to achieve online detection and characterization of FOID with quality control, digital MTF measuring machines, digital numerical aperture measuring machines, digital transmission measuring machines and digital resolution measuring machines are manufactured by using CCD technology and other devices. Precise measurement of FOID has been achieved. Measurement results and their impact factors have been analyzed in detail. Research results have clearly shown positive effects on real production. In this talk, I will first overview the concept and applications of FOID. I will then present our future work on advanced techniques.

Tuesday, 4 October 2016

Development of SurfSat: A CubeSat to Study On-orbit Spacecraft Charging Events

Speaker: Dr. Adrienne Dove
Location: OPB 234, 2:30pm
Abstract: Spacecraft in low-earth orbits are likely to experience charging issues due to the ambient plasma environment. The space radiation environment in Earth’s atmosphere is filled with hot and low-density plasmas that can cause charge to build up on spacecraft surfaces, resulting in high differential voltages and subsequent electrostatic discharges. If the exposed spacecraft materials are not properly bonded, differential charging can occur which can result in unwanted and damaging electrostatic discharge (ESD) events. These discharges can damage avionics and/or scientific instruments on spacecraft. We are designing a CubeSat that will take in-situ measurements of the ground current waveforms from chosen common spacecraft dielectric material samples, measure the spacecraft and material potentials, and monitor the ambient plasma environment. Comparison of on-orbit ESD measurements with completed and ongoing plasma chamber charging experiments will be used to validate current plasma charging test methods. These experiments will be used to develop design criteria, and help avoid potentially disastrous discharging on spacecraft. I will also discuss the general development CubeSats at UCF.

Tuesday, 27 September 2016

Using Bayesian Inference to Determine the Properties of Dense Matter

Speaker: Dr. Andrew Steiner (UT Knoxville)
Location: OPB 234, 2:30pm
Abstract: Neutron stars provide a unique laboratory in which we can study cold matter beyond the nuclear saturation density - a region of the QCD phase diagram which is inaccessible from laboratory experiments. In this talk, I describe how Bayesian inference connects the neutron star mass and radius measurements to the equation of state dense matter. In particular, neutron star radii give us information about the nuclear symmetry energy, one of the most uncertain parts of the nucleon-nucleon interaction.

Tuesday, 20 September 2016

Improving the Odds for Gravitational Wave Detection

Speaker: Dr. Tyson Littenberg (UAH CSPAR)
Location: OPB 234, 2:30pm
Abstract: The ability for gravitational wave observations to revolutionize our understanding of the universe is made possible in part by innovative data analysis strategies. This talk focuses on novel computational approaches used to squeeze every last drop of information out of the flood of gravitational-wave detector data.

Tuesday, 13 September 2016

Black Hole Masses in Active Galaxies

Speaker: Dr. Misty Bentz (GSU Physics & Astronomy)
Location: OPB 234, 2:30pm
Abstract: One of the more unexpected results from 20 years of Hubble Space Telescope observations is the discovery that supermassive black holes inhabit the centers of all massive galaxies. Furthermore, these black holes appear to have a symbiotic relationship with their host galaxies, in which each regulates the growth of the other. One of the keys to understanding this relationship relies upon knowing the masses of the black holes involved. However, black hole masses are difficult measurements to carry out because they require directly observing the gravitational influence of the black hole on a luminous tracer. A few different techniques have been developed over the last 20 years to meet these goals. One of these techniques, known as reverberation mapping, is exclusively applicable to active supermassive black holes but may be used on even the most distant quasars in our universe, providing a way to study black holes across history. On the other hand, the most widely used technique in the local universe is based on observations of the bulk motions of stars deep in the center of a (usually inactive) galaxy. I will introduce these two techniques and describe our ongoing program to identify a small sample of galaxies where BOTH techniques can be applied to every galaxy. This program will allow us to directly test the results of these independent mass measurement techniques and to investigate whether all black hole masses are on the same scale. The results of this work will have implications for our understanding of the evolution of galaxies across the ~13 billion year history of the universe.

Tuesday, 6 September 2016

Recent Progress in Middle-IR Lasers Based on TM:II-VI Semiconductors

Speakers: Drs. Sergey Vasilyev, Igor Moskalev, Mike Mirov, Viktor Smolski, Sergey Mirov (IPG Photonics)
Location: OPB 234, 2:30pm
Abstract: Transition-metal-doped II-VI semiconductors possess a unique blend of physical, spectroscopic, optical, and technological parameters. These materials enable high power lasers in important middle-infrared range; they are also well suited for generation and efficient nonlinear frequency conversion of ultra-short optical pulses. We present the most current achievements in room temperature Cr:ZnSe and Cr:ZnS lasers at 2.4 µm wavelength, including cw Cr:ZnSe laser with a power in excess of 140 W, ultra-fast Cr:ZnS lasers with multi-Watt power, as well as the results on nonlinear conversion of spectrally broad fs pulses in polycrystalline Cr:ZnSe and Cr:ZnS laser materials.

Tuesday, 30 August 2016

Faculty Mini Seminars II

Speakers: Drs. Bonamente, Duan, and Richard Miller (UAH Physics)
Location: OPB 234, 2:30pm
Abstract: Three short talks highlighting some current work in the Department of Physics and Astronomy. Graduate students and future PH 499 students are among those who may find these helpful.

Tuesday, 23 August 2016

Faculty Mini Seminars I

Speakers: Drs. Nishikawa, Sadeghi, and Sun (UAH Physics)
Location: OPB 234, 2:30pm
Abstract: Three short talks highlighting some current work in the Department of Physics and Astronomy. Graduate students and future PH 499 students are among those who may find these helpful.